Abstract
Eccrine porocarcinoma (EPC) is a very rare malignant adnexal tumor that arises from the intraepidermal portion of the sweat apparatus and accounts for 0,005 to 0.01% of all cutaneous malignancies. This tumor has a predilection for extremities, with acral surfaces are the most common site. However, only two cases of perianal EPC were reported in the literature. We present a case of a 52- year-old woman who presented with hematochezia and perianal mass. Radiologic findings (MRI) showed a 9 x 4 x 3.8 cm tumor involved the entire anal canal and extended to the lower rectum. Tumor invaded the levator ani muscle and the mesorectum. Histopathological examination of the tumor biopsy showed epidermal-based, atypical basaloid tumor cells arranging in broad anastomosing trabeculae and solid sheets with conspicuous ductal differentiation and focal intracytoplasmic vacuoles. Mitotic figures were numerous with atypical mitosis seen. Tumor cells were diffusely positive for CEA and p16 and were negative for p63, CK20 and CDX2 immunohistochemical stains. The final histopathological diagnosis was invasive eccrine porocarcinoma. As EPCs usually have a poor prognosis with a high risk of local recurrence and metastasis and may have aggressive local spread potential, a misdiagnosis of EPC might result in inappropriate treatment and misguided prognosis. The diagnosis of EPC is also challenging due to its rarity and non-specific appearance.
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