(Reactive) Eccrine Syringofibroadenoma with Foci of Squamous Cell Carcinoma in situ: A Case Report.

We describe a rare case of an eccrine syringofibroadenoma with a foci of squamous cell carcinoma in situ, which has to best of our knowledge been reported only twice in the English literature. An excisional biopsy of an elevated, lobular tumor of the lower leg in an 86-year-old male patient was performed. Histologic examination revealed a tumor consisting of anastomosing strands of epithelial cells originating from the epidermis, occasionally showing ductal eccrine differentiation. Foci of squamous cell carcinoma in situ were observed within the described lesion. The diagnosis of eccrine syringofibroadenoma with squamous cell carcinoma in situ was established. Eccrine syringofibroadenoma is a rare lesion, mostly considered to be a reactive process arising secondarily in association with other cutaneous diseases such as dermatoses or neoplasms, although some researchers do not exclude the possibility that it is a primary neoplasm with a potential for malignant transformation.