Colocalization of Lichen Planus Hypertrophicus and Epidermal Inclusion Cyst: An Incident Unreported Hitherto.

Colocalization of diseases in dermatology has always remained elusive and a puzzle, difficult to unscramble. Co-localization of two rare and disparate dermatoses has been reported on several occasions. Lichen planus (LP) has been described to colocalize with several dermatoses. We report here a case of LP hypertrophicus co-localizing with epidermoid cysts on the scrotum of a 35-year-old man for the unusual site and association.

What was known?

Colocalization of dermatoses is encountered in many cases

Lichen planus has been found to colocalize with many diseases such as vitiligo, Becker's nevus, and porokeratosis.

Introduction

Lichen planus (LP) is characterized by pruritic polygonal violaceous papules, thought to be the result of an autoimmune reaction to an unknown trigger. Lichen planus hypertrophicus (LPH) is most commonly found over the extensor aspect of lower extremities. Coexistence with other dermatoses is probably related to similar etiopathogenesis behind them. On the other hand, epidermal inclusion cyst is the result of plugged pilosebaceous duct and does not have any relation to autoimmunity. We report herein a case of LPH on scrotum in association with epidermoid cysts, for its rarity.

Case Report

A 36-year-old man presented to us with very itchy, grayish, elevated swellings over the scrotum present for the preceding 2 years. It started with a yellowish elevated non itchy skin lesion, which gradually turned into extremely pruritic lesion of darker color. Past history and family history were noncontributory. On examination, there were multiple grayish to flesh colored, firm plaques with few yellowish nodules over scrotum [Figure 1a and b]. There were a few mildly violaceous flat-topped plaques as well. Other mucocutaneous and systemic surveys were noncontributory. The excision biopsy specimen revealed a yellowish, firm nodular mass within the substance [Figure 2]. Histopathology showed compact orthokeratosis, hypergranulosis, marked irregular acanthosis with saw-toothing of rete ridges, band-like lymphocytic infiltrate at the dermo-epidermal junction with areas of basal cell degeneration, accentuated at the base of rete ridges. A cyst was also noted in the mid-dermis, filled with keratin, along with a few foci of calcification [Figures 3 and 4]. Routine laboratory tests were within normal limits. A diagnosis of isolated scrotal LPH with colocalization of epidermoid cyst was made and three intralesional injections of triamcinolone acetonide were administered at 3 weeks’ interval; resulting in resolution of lesions of LPH, leaving the cysts and areas of hyperpigmentation [Figure 5]. The patient declined further treatment and was kept on follow-up.

Figure 1

Multiple grayish to flesh colored, firm papulo-nodules and plaques over the right (a) and left (b) side of scrotum

Figure 2

The excision biopsy specimen showing a yellowish mass within the substance

Figure 3

Irregular acanthosis, compact orthokeratosis, hypergranulosis. A cyst filled with keratin, is appreciated the mid-dermis, along with a few foci of calcification (H and E, ×40)

Figure 4

Irregular acanthosis with saw-toothing of rete ridges and band-like lymphocytic infiltrate at the dermo-epidermal junction with areas of basal cell degeneration, accentuated at the base of rete ridges. (H and E, ×40)

Figure 5

Posttreatment clinical photograph showing resolution of lesions of lichen planus hypertrophicus, leaving the cysts and areas of hyperpigmentation

Discussion

Lichen planus is a common papulosquamous disorder involving the skin, nails, and mucosae. A variant is the hypertrophic or warty type better known as LPH. Lesions of LPH are characterized by hypertrophic verrucous plaques predominantly distributed over the shins or dorsal aspect of feet.[1] Histopathology shows marked irregular acanthosis, hypergranulosis, compact orthokeratosis, basal layer degeneration, and the lymphocytic inflammatory infiltrate is accentuated at the base of the rete ridges.[2]

Epidermoid cysts are keratin-filled epithelial lined cysts, mostly originating from the follicular infundibulum. They classically manifest as dermal or subcutaneous lesions, located on the upper chest, upper back, neck or head. Reported associations include Gardner's syndrome, nevoid basal cell carcinoma syndrome, and pachyonychia congenita type 2. Histopathology reveals cysts lined by stratified squamous epithelium and filled with keratin flakes.

There are a few reports of colocalization of epidermoid cysts with other dermatoses. Two cases of nevus comedonicus in association with epidermoid cysts were reported. Both the cases had multiple nodular swellings scattered within the area of nevus comedonicus, which were confirmed to be epidermoid cysts after histopathological examination.[3]

Similarly, coexistence of LP with a number of dermatological disorders is well documented. Autoimmunity being the basic pathogenetic mechanism behind the development of LP, this has been reported to occur along with vitiligo by many authors.[4] Another interesting case was of co-existence of vitiligo, LP, and Becker's nevus.[5] Colocalization of LP have also been described with subacute cutaneous lupus erythematosus, generalized morphea, lichen sclerosus,[6] generalized lichen amyloidosis,[7] Riehl's melanosis,[8] and psoriasis. A co-existence of LP and porokeratosis has also been reported in a 40-year-old man.[9]

To the best of our knowledge, presentation of LPH on scrotum and its colocalization with epidermoid cyst, has not been reported, in the literature.

What is new?

Colocalization of lichen planus hypertrophicus and epidermoid cyst that too in scrotum, is not reported yet; to the best of our knowledge.