Skin Diseases in Nutshell

·         SYPHILIS :---

I.P.=9-90 days,

responsiveness to Rx is assessed by VDRL.,

most contagious-papular skin rash,

Treponema pallidum,T.P. crosses placenta after 28 wks.,

most specific test-TPI.,

most common site of syphilitic aneurysm-ascending/proximal aorta,

with effective Rx -VDRL fall by 4 fold,

Congenital S.--sabre tibia , Rhagades ,Pseudoparalysis of parrot ,Hutchinson's teeth-incisors ,Diag.=IgM FTABS.,

Latent S.--minimum dose of penicillin=7.0 M.U.,

Primary S.--gummatous ulcer ,confirmatory test-dark field exam'n.,

Secondary S.--most sensitive test -TPH ,condyloma lata,commonest manifes.-rash,lesions-macule,papule,vesicles, usaually asymptomatic VDRL=1:2 dilution ,VDRL shows max. specificity,

Tertiary S.--aortic aneurysmseen ,RX OF SYPHILIS,

complications--( in preg.--miscarraige in preg. in 2&3rd trimester and stillbirth ) linear calcification of eary aortic aneurysms , aortic valvular insufficiency

·         Leprosy :--- TT,BT,LL,

Lepra reaction--Type-I-TT,BT Rx systemicsteroids, ENL/Type-II-LL,reversal reaction,

satellite nodules & virchow'scell seen,

slitsmear-ve leprosy--neuritic type,

ulnar nerve inv. Ist.,

Iris pearls seen,100% neural inv.,bacteriological &morphological index ,RX-paucibacillary

·         Psoriasis :---

exacerbated by lithium ,Beta blocker,anti-malarials,

Koebner's phenomenon seen,

Bulkeley memb. Seen,

micro-munro abcess ,

guttate-psoriasis--due streptococcal infec.,

nails in P.--Oil drop app.,oncholysis,Auspitz sign ,nail changes seen in 2/3 pt's ,

pustular P.--Rx-methotrexate ,topical vit.D-calcipotriol & Pustular psoriasis-generalised

Pustular psoriasis, another severe form of the disease, can occur in patients with preexisting psoriasis, or it can arise de novo. Pustular psoriasis can be generalized (von Zumbusch-type) or localized to the palms and soles. In either case, the condition is severe and debilitating.

The use of liver biopsy to monitor patients on methotrexate has been a source of great controversy. Liver biopsies are not routinely performed in patients with rheumatoid arthritis who are undergoing treatment with methotrexate, but liver biopsy has been advocated in patients with psoriasis. Patients with psoriasis who are treated with methotrexate are more prone to hepatic fibrosis, possibly because of their underlying disease or because of the concomitant treatments they are given. Current guidelines call for the use of liver biopsy in patients with psoriasis who have received a cumulative dose of 1 to 1.5 g of methotrexate and who do not have a history of liver disease or alcoholism. Biopsy should be performed early in the course of treatment in patients with a history of hepatitis C, alcoholism, or other liver disease. Risk factors for hepatotoxicity include heavy alcohol intake, obesity, a history of diabetes or hepatitis, and abnormal results on liver function testing.

Although methotrexate causes bone marrow suppression, routine bone marrow biopsies are not indicated. Close monitoring with a monthly CBC is needed.

·         Tinea infec. :---

Civatte bodies seen,

affects stratum corneum ,

Trichophyton--affects skin,hair,&nail,

KERION-caused by dermatophytes ,

T.capitis-org.trichiophyton .tonsurans & microsoprum ,

T.cruris--dhobi's itch,T.pedis--athelete's foot ,

T.unguium--org.,affects nail plate ,

Rxsystemic griseofulvin

·         Scabies :--- I.P.=4wks.,

by itch mite ,

norwegian S.-immunocompromised ,

S. in infants -face,

Rx-gammexane,benylbenzoate,tetmesol,sulphur oint

·         Pemphigus vulgaris :---

acantholysis seen,

intraepidermal bulla,

degeneration of basal cells,row of tombstones app.,

Nikolsky sign seen,

can occur due to Procarbazine

1) "chancroid--haemophilus ducreyi,soft chancre,multiple necrotic-tender penile ulcers,LN'S inv.,NO fever,DOC.sulphonamides"-------------------------((9))

2) "lichen planus---wickham's striae seen,hyperpig. Patches over legs,scarring alopecia,(plane,purple,polygonal,pruritic,papule),"-------------------------((8))

3) "LGV/lymphogranuloma venereum---chamydia trachomatis/Bedsonian org.,genital ulcer not seen,necrotizing granulomatous lymphadenitis ,DOC.-doxycycline ,LGV in females--proctitis,rectal stricture,elephantiasis,,Esthiomene is seen , Frei's test +ve."----------------------((8))

4) "acne vulgaris---Rx,nodulocystic acne,"----------------------------((7))

5) "AIDS---clinicalcriteria,screening test-ELISA,confirmatory test-ELISA+WB,karpas test used,oral hairy leukoplakia,PEP,kaposi sarcoma,aphthous ulcer seen."-------------------------------((7))

6) "alopecia areata---exlcamation mark seen ,Rx."--------------------((5))

7) "atopic dermatitis---( Itch is the disease ), "" DENNIE MORGAN FOLD "" seen"------((5))

8) "contact dermatitis---(delayed H.R-Type IV-induration),Nickel,(Berloque dermatitis-cosmetics),AIR-borne C.D.-due to Parthenium,Endogenous C.D.-seborreic D.,Atopic D., urticaria."--------------((5))

9) "gonorrhoea---commonest V.D.in india,I.P.=2-5days,pus per urethra,does not inv. Testes,Rx-procaine penicillin4.8megaunits+probenecid1g orally"-----------------------------------((4))

11) "icthyosis vulgaris---granular layer-absent,autosomal recessive,Crocodile skin/Sauroderma,drugs-INH,clofazimine,nicotinamide,"-----------------------------(4))

12) "Vitiligo---also seen in D.M.,Rx -psoralen used"-------------------------((4))

13) "Wood's ligth---coral red fluoresence --porphyria, WAVE-LENGTH=360nm"------------------((4))

14) candidiasis---( washerman's hand-intertrigo ) ( systamatic candidiasis -Rx ketoconazole -D.O.C.)------((3))

15) "dermatisis herpetiformis---multiple grouped papulovesicular lesion ,Rx-gluten free diet /DOC.-dapsone."------------------------((3))

16) erythema multiforme------------------------------((3))

17) "granloma inguinale---diag. Smear ,Rx-streptomycin"---------------((3))

18) "herpes simplex---most common site-face ,Rx-pri.H.S.=acyclovir, herpes genitalis"------------------((3))

19) "herpes zoster---ballooning seen , multiple grouped vesicle over T10 seg.ass. With pain"---------------((3))

20) "NAILS---koilonchia in iron def. Anemia , Beaus lines seen in arsenic poisoning ,leuconychia in liver failure ,onycholysis in psoriasis ,( nail infec.--- by Trichophyton ,Epidermophyton ,Candida …)(nail inv.in-psorisis,dermatophytosis,L.P.)"---------------((3))

21) pyoderma capitis---cyctic swelling over scalp with easily plkable hair--KOH staining done(?fungal)-------------------((3))

22) "pityriasis rosea---Fir-tree app. , Herald patch ,"----------------------------((3))

23) "psoralen+PUVA treatment---vitiligo,psorisis,mycosis fungoides"----------------------((3))

24) "SLE---& DLE---drugs causing chorthiazide ,chloroquine?,tetracycline,clofazimine…"--------------(3)

·         In anaphylaxix, Epinephtine 1:1000 given IM not SC.

·         2% risk of cephalosporin allergy in pt positive with penicillin skin test.

·         Epidermal detachment of less than 10% suggests Stevens-Johnson syndrome.

·         Gastrointestinal anaphylaxis generally presents as acute abdominal pain and vomiting that accompanies other IgE-mediated allergic symptoms. ( not IgA)

·         Contraindications to skin testing:

Patients who are taking beta blockers, tricyclic antidepressants, and monoamine oxidase inhibitors should not be skin tested because these drugs may complicate treatment of anaphylaxis.

Patients who take antihistamines need to be forewarned to discontinue their use before the scheduled appointment because residual effects may interfere with accurate skin testing results. Short-acting antihistamines (e.g., diphenhydramine, fexofenadine) should be discontinued for 24 hours; long-acting antihistamines (e.g., loratadine, certirizine) will interfere with skin testing results for up to 3 weeks.

Patients taking systemic corticosteroids should be advised to delay skin testing until 2 weeks after discontinuation because the anti-inflammatory effects of the steroid may preclude satisfactory skin testing results.

·         RAST stands for radioallergosorbent test, which is an in vitro measure of specific IgE.

Allergens are chemically linked to solid-phase supports (usually paper discs) that are incubated with a droplet of serum from the patient. If specific IgE antibodies are present in the serum, they will bind with the allergen to form a complex. In a second step, the discs are incubated with radiolabeled IgE antibodies from another species, usually rabbit. After incubation, all free-labeled anti-IgE is washed away, leaving the specific IgE with a radioactive tag to be counted.

RAST testing may be preferred to skin testing in atopic patients who show dermatographia or have extensive skin involvement. It is also helpful in evaluating anaphylactic allergens or testing in children. RAST is not effective in the diagnosis and treatment of nonatopic hypersensitivity.

·         Puncture skin test > Intradermal skin test > RAST (acc to apecificity ??)

·         Most allergens are proteins that have molecular weights of 10-70 kd. Molecules smaller than 10 kd would not bridge adjacent IgE antibody molecules on the surface of mast cells or basophils. Most molecules larger than 70 kd would not pass through mucosal surfaces needed to reach antigen-presenting cells for stimulation of the immune system.

·         There is an increased association of chronic urticaria with Hashimoto thyroiditis. Such patients generally have antibodies to thyroglobulin, or a microsomal-derived antigen (peroxidate) even if they are euthyroid. The incidence of abnormal thyroid function (either increased or decreased T4 and/or increased or decreased TSH) is approximately 20%. Patients with chronic urticaria usually have normal IgE levels.

·         The id reaction or autoeczematization is a cutaneous response to an infection in a remote location. The cause is unknown, but it is hypothesized that increased stimulation of normal T cells by altered skin constituents with lowering of the irritation threshold may be responsible.Successful treatment consisted of a yeast elimination diet and immunotherapy with dermatophyte extracts (trichophyton, oidiomycetes, and epidermophyton).

·         Tinea capitis treatment with topical antifungals should also include an oral antifungal agent owing to reduced absorption of topical formulations. In particular, ketoconazole shampoo should not be used because it is ineffective against scalp ringworm.

·         Phenytoin-induced skin eruption usually occur 7 to 21 days after initiation and almost always within the first 2 months of therapy. these reactions may proceed to fatal reactions, like toxic epidermal necrolysis and drug should be stooped if this occurs.

·         Anxiety and emotional stress primarily aggravate the hyperhidrosis of the palms and soles, but not of the axilla. The eccrine sweat glands of the palms and soles, as well as those of the forehead, respond to emotional, mental, or sensory stimuli, whereas the axillary glands respond primarily to thermal stimuli.

·         Kaposi varicelliform eruption, or eczema herpeticum, results from herpes simplex virus infection of skin with altered immunity, usually from atopic dermatitis. Kaposi varicelliform eruption is clinically distinguished from zoster by its random distribution, which may involve many dermatomes. Additionally, lesions of eczema herpeticum are often isolated and are not grouped, as are the vesicles of zoster. Similar eruptions have been described in association with vaccinia virus (smallpox vaccination) and coxsackievirus infections.

·         Erysipeloid occurs in persons employed as handlers of fish, poultry, or dead meat. It is a slowly evolving, painful cellulitis due to the gram-positive organism Erysipelothrix rhusiopathiae. Erysipelas is a cellulitis due to group A β-hemolytic streptococci. Ecthyma is impetigo that extends into the dermis. Erythrasma is often seen in patients with diabetes and consists of large, well-demarcated macules affecting the intertriginous areas of the body, especially the groin. The lesions are brownish-red and are due to Corynebacterium minutissimum, a gram-positive rod that is a part of normal skin flora.

·         Body hair are of 3 types:

Lanugo hair follicles: lightly pigmented, thin in diameter, found in neonates

Vellous hair follicles: fine, nonpigmented hair found in most body regions in adults

Terminal hair follicles: pigmented, coarse hair found in scalp, axilla, and pubic area of adult men and women, and face and chest of men.

·         Plantar warts are painful warts on the soles of the feet. They are flat or slightly raised areas of firm hyperkeratosis with a collarette of normal skin. Unlike calluses, with which they can be confused, plantar warts cause obliteration of the normal skin lines (dermatoglyphics).

·         Mastocytoma: This is a benign lesion composed of mast cells that arises at birth or during early infancy. It appears as a pink/tan plaque or nodule, often with a peau d'orange surface.

Darier sign refers to the eliciting of erythema and an urticarial wheal by stroking or rubbing the lesion. The skin changes are caused by the release of histamine from the mechanically traumatized mast cells.

·         Scarlet fever caused by group A beta hemolytic streptococcus and Kawasaki disease are the most common disorders associated with a strawberry tongue. The "strawberry-like" surface characteristics are caused by prominent lingual papillae. A white strawberry tongue is caused by fibrinous exudate overlying the tongue. Red strawberry tongues lack the fibrinous exudate.

·         Keratosis pilaris: Associated both with atopic dermatitis and ichthyosis vulgaris, this condition runs in families and is asymptomatic. It is characterized by spiny follicular papules, giving involved areas a "chicken skin" or "gooseflesh" feel. Usual treatment is with bland emollients or emollients that contain a mild peeling agent, such as alphahydroxy acid preparation.

·         Allergic contact dermatitis (shoe dermatitis): This condition often involves the dorsa of the toes and the distal third of the foot. The rash is red, scaly, and vesicular. KOH preparations of scrapings for fungus are negative.

Tinea pedis (athlete's foot): Presentations can include redness and scaling, primarily on the instep or the entire weight-bearing surface, or erythema and maceration between the toes, especially the third and fourth web spaces. A less-common presentation is one in which vesicular lesions develop, called bullous tinea pedis. In tinea pedis, the nails may be yellowed and thickened. KOH preparations are positive for hyphae. Tinea pedis is much less common in prepubertal children.

·         Twenty nail dystrophy (trachyonychia): The progressive development of rough nails with longitudinal grooves, pitting, chipping, ridges, and discoloration occurring in isolation in school-aged children has been given this name, although not all nails need be involved. The etiology remains unclear, and a majority of cases resolve spontaneously without scarring. The nail changes, however, may herald other conditions, such as alopecia areata, lichen planus, and psoriasis.

·         Hidradenitis suppurativa: an apocrine sweat gland infection of the axilla, groin, breasts, or buttocks that can cause inflammation and scarring. Hidradenitis suppurative sometimes responds to dicloxacillin or erythromycin, although surgical excision is sometimes required.

Erythrasma: a skin infection caused by Corynebacterium minutissimum that occurs in the axilla or groin or sometimes between the toes. Erythrasma responds to topical benzoyl peroxide or systemic erythromycin.

·         Cutis marmorata is the bluish mottling of the skin often seen in infants and young children who have been exposed to low temperatures or chilling. The reticulated marbling effect is the result of dilated capillaries and venules causing darkened areas on the skin; this disappears with warming. Cutis marmorata is of no medical significance, and no treatment is indicated. However, persistent cutis marmorata is associated with trisomy 21, trisomy 18, and Cornelia de Lange syndromes. There is also a congenital vascular anomaly called cutis marmorata telangiectatic congenita that has persistent purple reticulate mottling of the skin.

·         Subcorneal pustular dermatosis, or Sneddon-Wilkinson disease, is typically characterized by larger flaccid blisters with a more gradual onset. Some investigators consider this disease a variant of pustular psoriasis.

·         Aplasia cutis congenita (congenital absence of the skin) presents on the scalp as solitary or multiple well-demarcated ulcerations or atrophic scars. Of variable depth, the lesions may be limited to epidermis and upper dermis or occasionally extend into the skull and dura. Although most children with this lesion are normal without multiple anomalies, other associations include epidermolysis bullosa, placental infarcts, teratogens, sebaceous nevi, and limb anomalies. Aplasia cutis is a feature of trisomy 13 syndrome.

·         Ultraviolet light is divided into three wavelength groups:

ultraviolet C (UVC), 200-290 nm;

 UVB, 290-320 nm; and

 UVA, 320-400 nm.

 UVC light is cytotoxic and can cause retinal injury, but fortunately it is almost completely absorbed by the ozone layer.

 UVB light causes sunburn, dermatologic flares (e.g., in patients with lupus erythematosus), and, with chronic exposure, skin cancer.

 UVA light (which is also emitted from the fluorescent lamps used in most schools) is responsible for psoralen and drug phototoxicity and porphyria flares, and it can cause skin cancer with chronic exposure.

 Windows block UVB light, but not UVA. Thus, children with UVA-sensitive disorders would not be protected by sitting behind a window.

·         The Spitz nevus can appear suddenly and grow rapidly. Histologically, it has many features that can be mistaken for malignancy. It actually was previously referred to as benign juvenile melanoma. "Benign" is the key word for this red to brown, dome-shaped papule, which usually appears on the face or extremity. Clinicopathologic correlation is the key to making this diagnosis. It is essential that an experienced pathologist interpret the biopsy when a Spitz nevus is suspected.

 Melanoma in childhood has been misdiagnosed as Spitz nevi, and Spitz nevi have been misdiagnosed as melanoma.

·         Lipoid proteinosis is a very rare genodermatosis characterized by hoarseness, skin infiltration and thickening, beaded papules on eyelid margins, and facial acneiform or pock-like scars.

Histological examinations show an extracellular PAS-positive hyaline material.

The disorder is attributed to a mutation of the extracellular-matrix protein-1 located on chromosome 1q21.

·         Acute generalized exanthematous pustulosis (AGEP) is a cutaneous eruption in which dozens to hundreds of sterile nonfollicular pustules on edematous and erythematous bases appear acutely on the skin.

Ninety percent of cases have been associated with drug ingestion, namely, beta-lactam drugs and macrolides. Other implicated drug classes include antimycotics, calcium channel blockers, mercury, nonsteroidal anti-inflammatory drugs (NSAIDs), carbamazepine, and acetaminophen. Interestingly, AGEP has not been commonly attributed to sulfonamides, a frequent cause of other cutaneous drug reactions. Reactions to viral infections, such as enteroviruses and parvovirus B19, have also been noted in many cases

hallmark criteria of AGEP are as follows:

1.       Dozens of small, nonfollicular pustules on widespread edematous erythema

2.       Histopathology showing spongiform subcorneal and/or intraepidermal pustules, marked edema of papillary dermis, and perivascular infiltrates with neutrophils and exocytosis of some eosinophils

3.       Fever >100.4°F (38.0°C)

4.       Blood neutrophil counts >7 × 109 cells/L

5.       Acute evolution with spontaneous resolution of pustules in less than 15 days

·         Latex is an emulsion of rubber globules derived from the sap of plants of the Euphorbiacea family. Within the last 15 years, it has become a cause of serious allergic reactions.

The major allergen appears to be a protein fragment known as rubber elongation factor; it causes contact dermatitis, pruritus, urticaria, conjunctivitis, rhinitis, and asthma. In recent years, a number of cases of anaphylaxis have been reported, particularly among those frequently exposed such as health care workers, latex industry workers, and patients who undergo frequent operative procedures.

Latex sensitivity is so exquisite in sensitized individuals that they must avoid even the environments where latex is used. Aerosolized latex from the powder in gloves of coworkers has been known to cause reaction. Cross-reactions with avocado, bananas, chestnuts, and fruits have been reported.

·         Morphologic warning signs of MELANOMA:

mnemonic: ABCD

Asymmetry

Border

Color variation

Diameter increase

• Possible causes of ACANTHOSIS NIGRICANS:

mnemonic: PAID COb

Polycystic ovarian disease

Acromegaly

Insulin resistance

Diabetes mellitus

Cancer (colon, stomach)

Obesity

• Possible cause of migratory necrolytic erythema: GLUCAGONOMA

• Possible cause of acrodermatitis enteropathica: ZINC DEFICIENCY

• Precursor lesion of squamous cell carcinoma of the skin: ACTINIC KERATOSIS

• Precursor lesion of melanoma: DYSPLASTIC NEVUS

• ERYTHEMA NODOSUM: associated conditions:

mnemonic: BUMP SIS

Behçet’s syndrome, birth control pills (BCPs)

Ulcerative colitis

MTB

Parasites

Sarcoidosis, sulfonamides

Inflammatory bowel disease

Streptococcal and fungal infections

• Erythema chronicum migrans (ECM): Lyme disease

• Erythema migrans lingualis: geographic tongue (erythema migrans of the tongue)

• Erythema marginatum: rheumatic fever

• Erythema multiforme: Stevens-Johnson Syndrome, sulfonamides, NSAIDS, Dilantin

• Pityriasis rosea: initial lesion “herald patch”; other lesions follow a “Christmas

tree” pattern

• “Ice pick”-like pitting of the nails: specific for psoriasis

·         A beard area hemangioma may herald a subglottic lesion that could be life-threatening and may be the source of the perceived asthma symptoms.

·         Hypohidrotic ectodermal dysplasia:

XR, anomalous dentition

Patients usually have hypotrichosis. Because of the inability to sweat, these children often have many episodes of high fever; therefore, this entity is included in the differential diagnosis of fever of unknown origin.

·         PHACES is associated with posterior fossa defects such as Dandy-Walker cysts or cerebellar hypoplasia. Strokes are a major source of morbidity.

·         Cutis marmorata is an accentuated physiologic vasomotor response that disappears with increasing age during the first year of life.

·         Erythema toxicum is a benign, self-limited, evanescent eruption that occurs in approximately 50% of full-term infants; preterm infants are affected less commonly. The lesions are firm, yellow-white, 1- to 2-mm papules or pustules with a surrounding erythematous flare. Lesions may be sparse or numerous and clustered in several sites or widely dispersed over much of the body surface. Palms and soles are usually spared. Peak incidence is on the second day of life, but new lesions may erupt during the first few days as the rash waxes and wanes.

·         The most effective treatment for port-wine stains is the flashlamp-pumped-pulsed dye laser. This therapy is targeted at the lesion and avoids thermal injury to the surrounding normal tissue. Alternative therapies include masking with cosmetics, cryosurgery, excision, grafting, and tattooing.

·         Acrodermatitis enteropathica is caused by an inability to absorb sufficient zinc from the diet. Initial signs and symptoms occur during infancy and consist of a rash in the perioral, acral, and perineal areas and on the cheeks, knees, and elbows. There is often alopecia and chronic diarrhea. Some patients with cystic fibrosis present with a similar rash. Biotinidase deficiency should be in the differential diagnosis. Treatment of acrodermatitis enteropathica is with oral zinc compounds.

·         red lunula seen in: 1. AIDS 2. Rheumatoid arthritis 3. systemic lupus erythematosus 4.alopecia areata 5.cardiac failure 6. chronic systemic diseases

·         foot prints in snow pattern: pseudopelade - Pseudopelade of Brocq is an end stage or clinical variant of various other forms of scarring alopecia and a diagnosis of exclusion. The same pattern of hair loss can be seen in burnt out (ie, no clinical or histologic evidence of inflammation) discoid lupus erythematosus (DLE), lichen planopilaris (LLP), and other forms of scarring alopecia. If a definitive diagnosis of DLE, LPP, or another condition can be made based on clinical, histologic, or immunofluorescent features, then the term pseudopelade of Brocq cannot be used. A primary form of traditional pseudopelade may exist, but this has yet to be established with certainty.

·         Lupus Perniois one of the few cutaneous manifestations that are characteristic of sarcoidosis. Lesions are chronic, indurated papules or plaques that affect the mid-face, particularly the alar rim of the nose. Even a few small papules in this location may be associated with granulomatous infiltration of the nasal mucosa and upper respiratory tract, resulting in masses, ulcerations, or even life-threatening airway obstruction.

Lupus perniois a chronic raised indurated (hardened) lesion of the skin, often purplish in color. It resembles frostbite as it is seen on ears, cheeks, lips, nose, hands, fingers, and forehead. It is most often associated with sarcoidosis. Microscopically, it resembles Lupus vulgaris. Biopsy shows granulomatous infiltration.

·         Poikiloderma of Civatte refers to erythema associated with a mottled pigmentation seen on the sides of the neck, most commonly in women. Civatte first described the condition in 1923. Poikiloderma of Civatte is a condition affecting the skin. Many consider it to be a reaction pattern of the skin and not a disease. The term poikiloderma refers to the combination of atrophy, telangiectasia, and pigmentary changes (both hypopigmentation and hyperpigmentation). Poikilodermatous lesions may be seen in certain genodermatoses (Rothmund-Thomson syndrome, Bloom syndrome, dyskeratosis congenita), in connective tissue diseases (dermatomyositis, lupus erythematosus), in parapsoriasis/mycosis fungoides, and in radiodermatitis.

·         V. vulnificus infection can present as two distinct clinical syndromes: one arises from minor trauma sustained while swimming in lakes or the ocean or while cleaning seafood. Cellulitis occurs, with lymphangitis and bacteremia. In patients with hepatic cirrhosis, a systemic infection can occur after eating raw oysters. These patients develop hemorrhagic bullae, with leukopenia and disseminated intravascular coagulation (DIC). Other groups at risk for the systemic form of the disease are those with hemosiderosis, chronic alcohol abuse, and chronic liver disease other than cirrhosis.

·         Etiologies of the ichthyoses are diverse, but the ichthyoses share common manifestations and treatments. The most common form is ichthyosis vulgaris, which is inherited in an autosomal dominant fashion; disease onset occurs in patients 3 to 12 months of age. Other forms of ichthyoses include recessive X-linked ichthyosis, lamellar ichthyosis, congenital ichthyosiform erythroderma, epidermolytic hyperkeratosis, and acquired ichthyosis. Acquired ichthyosis is associated with multiple disorders, including HIV infection and endocrinopathies; it can also occur as a paraneoplastic syndrome that is usually associated with lymphomas and carcinomas. Epidermolytic hyperkeratosis is the most difficult form to treat because therapeutic agents can induce blistering. Standard therapies are emollients (such as petrolatum) and keratolytics (such as lactic acid with or without propylene glycol). Antimicrobial agents are also frequently used to combat the odor and other complications of bacterial colonization of the affected skin.

·         natural rubber and latex allergy have some cross-reactivity with certain fruits, including avocados, chestnuts, kiwi, and bananas

·         The etiology of the ampicillin rash that occurs in association with a viral infection is unknown, but the rash does not appear to be IgE-mediated. Patients can tolerate all β-lactam antibiotics, including ampicillin, once the infectious process has resolved. Fever is not associated with simple exanthematous eruptions. These eruptions usually occur within 1 week after the beginning of therapy and generally resolve within 7 to 14 days. The exanthem’s turning from bright red to brownish red marks resolution. Resolution may be followed by scaling or desquamation. The treatment of simple exanthematous eruptions is generally supportive. For example, oral antihistamines used in conjunction with soothing baths may help relieve pruritus. Topical corticosteroids are indicated when antihistamines do not provide relief. Systemic corticosteroids are used only in severe cases. Discontinuance of the offending agent is recommended.

·         For urticarial lesions that persist for longer than 24 hours, consideration should be given to the use of biopsy to exclude vasculitis. Biopsy may show deposits of IgM and C3 immune complexes within the lesions. Besides being associated with type I reactions, urticaria may occur with type III hypersensitivity reactions and as a result of nonimmunologic release of histamine caused by certain drugs, such as morphine. Treatment of severe allergic reactions includes epinephrine, antihistamines, bronchodilators, corticosteroids, and supportive treatment with fluids and pressors if needed. Patients can be desensitized if there is no therapeutic alternative to the causative drug.

·         It is important to consider the diagnosis of myiasis because occluding the punctum with fatty bacon causes the larvae to protrude. The larvae can then be removed with forceps. Other occlusive substances, such as petroleum jelly and nail polish, have also been effective. Excising the nodule for pathologic evaluation is not needed.

·         Tungiasis (sandflea cutaneous infestation), seabather’s eruption (infestation with larvae of the thimble jellyfish), swimmer’s itch (infestation with cercarial larvae of an avian schistosome), and cutaneous larva migrans (infestation with hookworm larvae) can all cause intensely pruritic skin lesions. It is the migration of larval hookworms that causes the serpiginous or linear tracks in the skin. Tungiasis causes erythematous edematous papules in clusters. Seabather’s eruption presents as a pruritic dermatitis in areas covered by swimwear. Swimmer’s itch is a papulovesicular eruption on exposed skin sites. The larvae of the botfly cause myiasis, a nonpruritic nodular skin lesion mimicking an infected cyst or abscess.

·         Seborrheic keratosis is a very common epithelial tumor that tends to occur on the upper trunks of light-skinned adults. They occur more frequently with increasing age. The color can range from dirty yellow to dark brown, and their size varies from 1 mm to several cm. They may be rough or smooth but often have a waxy surface. Dermatosis papulosa nigra is similar to seborrheic keratosis but tends to occur in dark-skinned individuals (this patient is white) and is usually localized on the face. In addition, dermatosis papulosa nigra tends to present at an earlier age than does seborrheic keratosis. The differential diagnosis of seborrheic keratosis also includes lentigo, warts, nevus cell nevus, and pigmented basal cell carcinoma. Inflamed seborrheic keratosis can be difficult to distinguish from malignant melanoma and squamous cell carcinoma. Transient development of seborrheic keratosis has been associated with inflammatory skin conditions such as drug-related erythroderma and psoriasis. The sign of Leser-Trelat is transient eruptive seborrheic keratosis that is associated with internal malignancy (especially adenocarcinoma); the validity of this sign is a subject of debate.

·         Nevus cell nevus (melanocytic nevus) is the most common skin tumor, and most young adults have 20 to 40 of these lesions. The incidence increases with age up to the second or third decade, then declines. These nevi are more common in sun-exposed areas. It is important to realize that the risk of melanoma increases with the number of melanocytic nevi. However, the presence of even one dysplastic nevus increases a person’s risk of melanoma. Therefore, it is important to be familiar with the appearance of dysplastic nevi (the features of which are similar to those of melanoma). Features include large size (> 5 mm), flatness, irregular pigmentation, asymmetry, and indistinct borders.

·         Isotretinoin use is associated with important side effects. Some of the reported side effects are cheilitis, dryness of mucous membranes and skin, myalgias, pseudotumor cerebri, and hypercholesterolemia. Triglyceride levels can rise significantly: enough to cause acute pancreatitis. Because teratogenicity occurs with even a single dose of isotretinoin, patients should undergo pregnancy testing repeatedly and should use two different methods of contraception. There have been reports of depression and suicide in isotretinoin-treated patients. This association remains controversial, but this risk must be discussed with the patient before starting therapy.

·         Medications causing drug-induced hyperpigmentation include oral contraceptives, hormone replacement therapies, antibiotics, antidepressants, antiviral agents, antimalarials, antihypertensives, and chemotherapeutic agents.

·         Chédiak-Higashi syndrome is characterized by recurrent infections, peripheral neuropathy, and oculocutaneous hypopigmentation. This disorder leads to death at an early age as a result of lymphoreticular malignancies or infections. The presence of giant lysomal granules in the neutrophils is characteristic of Chédiak-Higashi syndrome. Prader-Willi syndrome is a developmental syndrome characterized initially by mental retardation, neonatal hypotonia, and poor feeding, followed by hyperphagia and obesity. Patients have ocular abnormalities and skin and hair hypopigmentation consistent with oculocutaneous albinism. Hermansky-Pudlak syndrome presents as a hemorrhagic diathesis. Skin and hair color varies from white to light brown. Freckles and lentigines develop with age. Cross McKusick-Breen syndrome is characterized by hypopigmentation, microphthalmia, nystagmus, and severe mental and physical retardation.

·         Type 5 neurofibromatosis manifests as skin lesions in a focal dermatomal segment caused by a localized mutation occurring during embryonic development. It does not carry the risk of the CNS tumors, cortical cataracts, or multiorgan system involvement seen with other types of neurofibromatosis. Additionally, focal dermatomal mutations do not affect the germline cells and are therefore not heritable, in contrast to the autosomal dominant pattern of inheritance of the other neurofibromatosis disorders. Therefore, there is no need for genetic counseling. Although ophthalmologic screening can confirm neurofibromatosis type 1 by finding Lisch nodules (iris hamartomas), this screening is not necessary in patients with type 5 neurofibromatosis because there is no associated eye disorder. Diagnosis of type 5 neurofibromatosis is made by inspection of the skin lesions, and no biopsy is required. Topical steroids have no effect on café au lait spots or neurofibromas.

·         Indirect immunofluorescence test results are usually negative in cicatricial pemphigoid and positive in pemphigus.