Extramammary Paget's disease mimicking acantholytic squamous cell carcinoma in situ: a case report.

BACKGROUND

Extramammary Paget's disease (EMPD) is an uncommon skin neoplasm characterized by Paget's cells with pale-staining cytoplasm in the epidermis, and cases with distinguished acantholysis but lacking characteristic Paget's cells were rarely reported in the literature.

METHODS

An 80-year-old male with lesion on scrotum was screened histologically and immunohistologically for the diagnosis of his tumor.

RESULTS

Histological examination showed acanthosis with cellular atypia and focal acantholysis, consistent with acantholytic squamous cell carcinoma in situ (SCCIS). No characteristic Paget's cells were observed in low magnification. Immunohistochemical staining showed carcinoembryonic antigen (CEA), cytokeratin 7 (CK7) and cytokeratin 8 (CK8) to be strongly expressed in the nests and singly arranged large tumor cells, and the surrounding epidermis was positive for CK5/6 and negative for CEA. Sporadic periodic acid-schiff (PAS)-positive cells could be seen in some areas.

CONCLUSIONS

These findings strongly indicated the diagnosis of EMPD mimicking acantholytic SCCIS.