A giant benign clear cell hidradenoma on the anterior trunk

Clear cell hidroadenoma (CCA) is a uncommon variant of bening cutaneous adnexial tumors. These tumors are clinically asymptomatic, solitary dermal nodules. they occur most frequently on the scalp, face, abdomen and the extremities. Growth is slow and malignant change is rare. 45- year-old woman presented us with a nodule with a central ulceration and a minimal hemoragic discharge on her anterior abdomen wall which had begun 4 years ago as a small nodular asymptomatic lesion. On dermatological examination there was a 6.5x4x5 cm non-tender, soft reddish purple nodule with lobular appearence and ulceration. In the laboratory investigations, all the hematologic and biochemical tests were normal. A CT scan demonstrated a cyctic tumor with lobulated countour with contrast enhancement. The lesion excised totally. In histopathological examination the tumor was composed of biphasic  smaller dark polygonal cells and larger clera cells and coarse nuclear chromatine. There were duct like structures. Immunohistochemical investigation was done for the suspicion of malignancy. Cytoplasm of clear cells and duct like structures showed PAS positive and d-Pas resistant staining. There was a positive reactivity to epithelial membrane antigen and carcinoembrionic antigen. The mitotic index in Ki 67 examination was low. All these findings confirmed the diagnosis of bening CCA.