Skin, Extramammary Paget disease

Extramammary Paget disease is a rare intraepidermal adenocarcinoma that shows glandular differentiation. It is commonly found on the vulva, perineum, and scrotum and often presents as erythematous, pruritic, well-defined plaques. This case shows Paget disease with focal superficial invasion. The lesion was incompletely excised as the peripheral margins are positive.

Histologically, nests of malignant cells can be seen throughout the epidermis. These cells have a pale appearance with vacuolated cytoplasm. Pleiomorphism and prominent nucleoli are also present. Although Paget disease typically occurs in the epidermal region, high grade lesions involve invasion into the dermis or subcutis regions. The main differential diagnoses of pagetoid pattern malignancies include Paget disease (mammary and extramammary), melanoma, and Bowen's disease.