"Fountain sign" in lichen planus hypertrophicus

To the Editor

Various signs characterize various dermatoses e.g. ′dimple sign′ in dermatofibroma, ′carpet tack sign′ in discoid lupus erythematosus, ′Darier′s sign′ in urticaria pigmentosa, ′Nikolsky′s sign′ in pemphigus vulgaris are to name a few. We have earlier highlighted "nose sign" in a couple of dermatoses[1] and hanging curtain sign" in pityriasis rosea.[2] I herein describe a sign recently observed by me in cases of lichen planus hypertrophicus (LPH).

Lesions of LPH are characterized by hypertrophic verrucous plaques predominantly distributed over the shins.[3] The hair follicular openings remain patulous within these hypertrophic plaques. Since they are quite resistant to treatment by topical corticosteroids, intralesional injection of triamcinolone acetonide has been recommended for these lesions.[3]

While injecting these plaques with corticosteroids by a 26G needle, it has been often found that the medicine comes out through the follicular openings in a jet mimicking a "fountain". This phenomenon is mostly seen in LPH lesions of less than 2 years duration.

In the histopathology of LPH, often there is hydropic degeneration of the hair follicular wall in addition to the basal cell degeneration.[4] It is quite possible that as a result of degeneration of hair follicutlar wall, the injected drug passes through the pilosebaceous canal easily and is ejected out forcefully through the follicular openings during intralesional injection.

Some degree of degeneration of the hair follicular wall occurs in cases of DLE also. However, this phenomenon is not seen while putting intralesional injections in hypertrophic DLE lesions(s). This is probably because of the fact that the follicular openings in DLE lesions remain blocked by greasy scales responsible for "carpet tack sign". Perhaps perifollicular scarring is also responsible for prevention of entry of the drug into the pilosebaceous canals.