A Case of Hidroacanthoma Simplex
A 62-year-old Chinese woman presented with a 50-year history of brown tumor on the left lumbar part. She described a pink-colored indolent nodule that had appeared on her left lumbar region 50 years ago. The nodule was circumscribed and protruding over the peripheral skin. She did not feel any pruritus or pain at the tumor site. The tumor enlarged quickly in the last 2 years. And the color of tumor surface became dark gradually. No previous history of trauma on the area could be elicited. Her medical and family history was noncontributory.\nPhysical examination revealed a 7.0 × 4.8 × 0.5 cm, well-circumscribed, brown-colored, sessile tumor on the left lumbar part. The surface was covered with rough reddish-brown crusts []. The tumor was firm, nontender, and nonbleeding. There was no sentinel lymphandenopathy. Thorax CT scan and abdomen ultrasonic examination both were normal. Under local anesthesia, a biopsy was performed on the edge of the tumor.\nThe histopathology showed broad anastomosing tracts of cuboidal cells, with uniform nuclei originating from the epidermis in the tumor tissue. It was constructed by basal-like cells with uniform size and shape. Tubular structures were appeared within the neoplasm. There was no atypia or mitosis of cells [Figures -]. Immunohistochemical study showed the tumor tissue sections were positive for EMA [] and negative for CK7, 17, 18. So the patient was confirmed as a case of hidroacanthoma simplex by histopathology and immunohistochemical study.\nThe tumor was removed by surgery. The excision was extended 0.5 cm beyond the edge of the lesion, up to the adipose layer in depth. The histopathology of excisional mass border confirmed the tumor was removed entirely. Hybridization in situ indicated a negative reaction for human papilloma virus. The operation was successful. She had no recurrence after 6 months.