A Case of Giant Malignant Clear Cell Hidradenoma

Originating in the eccrine gland and occurring mostly in those above 50 years-old, malignant clear cell hidradenoma is a very rare type of tumor, compared to the common benign hidradenoma. To the author's knowledge, there have been only 4 cases reported worldwide of the malignant transformation, especially in nodular hidradenomas. Clinical manifestation of malignant clear cell hidradenoma includes an appearance of a single tumor generally in either extremities or head, which prevails for a long period and then suddenly enlarges from external stimuli, such as trauma, electrical cauterization or incomplete excision. With its aggressive behavior, it frequently recurs after surgical excision and has high tendency for regional and distant metastasis. We report on our experience on a 75 year-old woman with a 15×7×8 cm malignant clear cell hidradenoma, a malignant tran- formation in the long standing nodular hidradenoma, in the right postauricular region and the parotid gland region. (Korean J