Answer

Diagnosis: Irritated seborrhiec keratosis.

Synonym

Basosquamous cell acanthoma, Inflamed seborrhiec keratosis.

Asymptomatic pigmented growth in an elderly man in sun exposed area with histopathology showing squamous and basaloid cells with squamous eddies and several horncysts confirms the diagnosis irritated seborrheic keratosis.

Discussion

The seborrhiec keratoses (also known as "seborrhiec verruca", "brown wart", "basal cell papilloma" and "senile wart") are noncancerous benign skin growth that originates from keratinocytes. They usually involve sun exposed areas like face, scalp, upper trunk, and upper limbs. Their morphology is varied and multiple. They begin as brown pigmented macules and develop gradually in to slightly raised, brown to black, oval or polypoidal papules with a 'stuck-on' appearance. The surface of the lesion can be uneven, verrucous, and dull. They may be pedunculated resembling skin tags, but with a rough surface. Clinical variants include dermatosis papulosa nigra, stucoo keratosis, and melanoacanthoma.

Etiology of seborrhiec keratosis is not known. There is a possible role of epidermal growth factors or its receptors in the development of seborrhiec keratosis. ^[1],[2] BCL 2 (B cell lymphoma 2), an apoptosis suppressing oncogene, has a low expression in seborrhiec keratosis in contrast to high values seen in squamous and basal cell carcinoma. ^[3] A high frequency of mutations of tyrosene kinase receptor FGFR3 (fibroblast growth factor receptor 3) has been found in certain types of seborrhiec keratosis. ^[4],[5],[6] Mutations were identified in 39% of seborrhies kearatosis. Chronic exposure to sun is the main etiological factor in the development of seborrhiec keratoses. Generalized and eruptive presentation is associated with malignant conditions like gastrointestinal malignanacy, breast carcinoma, lymphoma, leukemia, and melanoma. It may also be associated with palmoplantar keratoderma, and acanthosis nigricans.

There are many histological types of seborrhiec keratoses which are seen like most common acanthotic, adenoid, hyperkeratotic, irritated, clonal, melanoacanthoma, pigmented, and inverted follicular keratoses. Uncommonly, there may be bowenoid transformation or carcinoma in situ within the lesion and rarely, basal cell carcinoma may develop. In the irritated or activated type of seborrhiec keratoses, squamous cells outnumber basaloid cells, shows the presence of 'squamous eddies' (eosinophilic, flattened squamous cells arranged in 'onion peel' fashion) in the epidermis, resembling poorly differentiated horn pearls. These squamous eddies are differentated from the keratin pearls of squamous cell carcinoma by their small size, large number and well circumscribed configuration. Squamous cells are the predominated variant seen in epidermis. The pathogenesis of squamous eddies is the result of activation of resting basaloid cells into squamous cells. These squamous eddies are also seen in inverted follicular keratoses and follicular poroma. ^[7],[8]

Konishi E et al, have reported irritated type of seborrhiec keratosis from right external ear canal in an elderly male. ^[9] Lee JP et al, reported a case of irritated seborrhiec keratosis from a previous incision site. ^[10]

A treatment option for seborrhiec keratosis includes simple curettage, cautery or cryotherapy. Often they tend to recur; patients should be advised regarding the benign nature of the condition with reassurance.