Extramammary Paget disease (EMPD) is a rare dermatologic condition that frequently presents in areas where apocrine sweat glands are abundant, most commonly the vulva, although perineal, scrotal, perianal, and penile skin may also be affected. Lesions clinically present as erythematous, well-demarcated plaques that may become erosive, ulcerated, scaly, or eczematous. Extramammary Paget disease has a female predominance and usually occurs in the sixth to eighth decades of life. Professionals disagree about many aspects of EMPD, for example, the prevalence of concurrent vulvar adenocarcinoma or invasive EMPD, association with regional and distant cancers, and recurrence rates following surgical excision. Early recognition is imperative because the diagnosis is frequently delayed and there is a high incidence of associated invasive disease.
Histological, immunohistochemical, and ultrastructural studies were performed on two cases of histologically unusual extramammary Paget's disease. Histologically, the central area of the lesions showed a bowenoid pattern, and the peripheral area showed typical extramammary Paget's disease. The transition zone showed an intermediate pattern. All these areas were positive for CEA and EMA, and negative for S-100 protein. Ultrastructurally, in the intermediate pattern, the tumour cells had abundant cytoplasmic glycogen, and the widened intercellular spaces contained numerous glycogen particles, which were probably secreted by the tumour cells. It is well known that eccrine glands, but not apocrine glands, secrete glycogen particles. Therefore, the present findings suggest that some cases of extramammary Paget's disease are a proliferation of germinative cells with eccrine gland differentiation.