Dermatology Signs

         Nikolskiy sign:  A positive Nikolskiy sign indicates intraepidermal cleavage and differentiates intraepidermal blisters from subepidermal blisters. It is pathognomonic of pemphigus and staphylococcal scalded skin syndrome. The sign may also be elicitable in the rare ichthyosis bullosa of Siemens, where it is termed the `mauserung phenomenon'.

Nikolskiy sign may be elicited over the normal looking skin of a pemphigus patient either close to existing lesions (marginal Nikolskiy sign) or over normal looking skin at a distant site (direct Nikolskiy sign).6 A positive direct Nikolskiy sign indicates severe activity of the disease in pemphigus. It is the first sign to disappear as the disease responds to therapy; the marginal Nikolskiy sign may persist for some time.

·         Bulla spread sign: In the traditional "bulla spread" sign or Lutz sign, the margin of an intact bulla is first marked by a pen. Slow, careful and unidirectional pressure applied by a finger to the bulla causes peripheral extension of the bulla beyond the marked margin. The bulla thus extended has an irregular angulated border in pemphigus vulgaris, while a regular rounded border is observed in bullous pemphigoid or other subepidermal blistering disorders.

This sign is positive in all varieties of pemphigus and many cases of subepidermal blisters, including bullous pemphigoid, dermatitis herpetiformis, epidermolysis bullosa acquisita, cicatricial pemphigoid, dystrophic epidermolysis bullosa, Stevens-Johnson syndrome and toxic epidermal necrolysis. Due to fragility of the roof of the blister it is usually negative in Hailey-Hailey disease and staphylococcal scalded skin syndrome.

·         Sheklakov sign/False Nikolskiy sign: This sign is positive in subepidermal blistering disorders, like bullous pemphigoid, cicatricial pemphigoid, herpes gestationis, dermatitis herpetiformis, linear IgA bullous dermatotis, epidermolysis bullosa acquisita, junctional and dystrophic epidermolysis bullosa, porphyrias and bullous SLE.

This involves pulling the peripheral remnant of a roof of a ruptured blister, thereby extending the erosion on the surrounding normal appearing skin. It is called the "false Nikolskiy" sign because it is a subepidermal cleavage occurring in the perilesional skin.6 The erosions thus induced are limited in size, do not exhibit tendency to subsequent spontaneous extension and heal rapidly.

·         Pseudo-Nikolskiy sign/Epidermal peeling sign: This sign is positive in Stevens-Johnson syndrome, toxic epidermal necrolysis and in some cases of burns and bullous ichthyosiform erythroderma. The method and mechanism of elicitation is the same as for Nikolskiy sign. However, it can be elicited only on the involved or erythematous areas. This phenomenon has been described as Nikolskiy sign in most textbooks.10-12 However, the underlying mechanism here is the necrosis of epidermal cells and not acantholysis as in true Nikolskiy sign.

·         Auspitz sign: When the scales are completely scraped off, the stratum mucosum (basement membrane) is exposed and is seen as a moist red surface (membrane of Bulkeley) through which dilated capillaries at the tip of elongated dermal papillae are torn, leading to multiple bleeding points. 

This is a characteristic feature of psoriasis and is known as Auspitz sign. It is attributed to parakeratosis, suprapapillary thinning of the stratum malphighii, elongation of dermal papillae and dilatation and tortuosity of the papillary capillaries.

However, Auspitz sign is not sensitive or specific for psoriasis. It is not seen in inverse psoriasis; pustular, erythrodermic psoriasis; guttate psoriasis. Not specific because it is also seen in nonpsoriatic scaling disorders, including Darier′s disease and actinic keratosis.

·         Carpet tack sign (cat′s tongue sign, tin tack sign):In DLE, characteristic lesions are well-defined erythematous plaques with partially adherent scales entering a patulous follicle. When the scale is removed, its undersurface shows horny plugs that had occupied follicles. This is called the carpet tack or tintack sign.

However, carpet tack sign is not diagnostic of DLE. It is also seen in seborrheic dermatitis and pemphigus foliaceous. But in DLE, on removal of scale, bleeding may be seen due to adherent scales unlike in pemphigus foliaceous/seborrheic dermatitis, where the scales are loose.

·         Scratch sign (coup d′ongle sign, besnier′s sign, stroke of the nail):

Pityriasis versicolor is characterized by asymptomatic hypopigmented or hyperpigmented macules and patches and produces fine scales (branny/furfuraceous). Often the scale is not visible. An important diagnostic clue may be the loosing of barely perceptible scale with a fingernail, which is called as the scratch sign.

This sign may be negative if patient has taken recent bath or in case of treated lesion, in which case, only hypopigmentation persists.

With tinea versicolor, KOH examination reveals a characteristic “spaghetti and meatball” appearance. The fragments of hyphae are the “spaghetti,” and the round yeast cells are the “meatballs.”

• Darrier’s sign: Urticaria pigmentosa (Mastocytosis)

• Auspitz sign: Psoriasis

• Nikolsky sign: A canthoytic disorders Eg: Pemphigus, SSSS, TEN.

• Carpet tack sign: DLE

• Button hole sign: Neurofibromatosis

• Apple jelly nodules: Lupus vulgaris

• Bulla spread sign: Pemphigus

• Gottron’s sign: Dermatomyositis

• Oil drop sign: Psoriasis

• Shawl sign: Dermatomyositus

• Pseudo sign: Smooth muscle hamartomas

• Lesser Trelaut sign: E. Seborrheic keratosis

• Dennie morgan fold: Atopic dermatitis

• Hebra’s triangle: Scabies

• Groove’s sign: LGV

• CLUE Cells: Bacterial vaginosis

• Target Lesions: EMF

• Buschke-Ollendorf sign: Papular syphilis

• String of pearls: IgA dermatoses

• Pathergy test: Behcet disease, PG

• Kobeners phenomenon: LP, psoriasis, vitilgo, warts, Darriens, Xanthomas Reticulo histocytes

• Dimple Sign: Dermatofibroma