Malignant sweat gland tumor presenting as an unusual dural-based lesion: case report.

Malignant sweat gland tumors are rare neoplasms with high recurrence and metastasis rates of over 50%. Clinically, they are often either not diagnosed or diagnosed improperly and are encountered as a histological surprise. Herein, we report a 50-year-old woman who suffered from chronic headaches and a left-side limping gait. Magnetic resonance imaging revealed a T1 and T2 heterogeneous intense dural-based lesion at right-frontal convexity. The pathological diagnosis of papillary meningioma was rendered at the time. Because there was no evidence of residual tumor, tumor recurrence, or distant metastases during the three-year follow-up, the clinician believed questioning the initial diagnosis was warranted. After pathological review, the final diagnosis was low-grade hidradenocarcinoma. A review of the literature suggests this is the first reported case of dural-based hidradenocarcinoma with local brain invasion. Given the lack of scalp or skull bone involvement, we speculated that the tumor may have arisen from ectopic sweat gland cells entrapped in the dural mater.