Case Report: Eccrine spiradenoma of the shoulder mimicking a vascular lesion on ultrasonography and CT

Eccrine spiradenoma is an uncommon benign cutaneous adnexal tumor that presents as a painful dermal or subcutaneous nodule. Prominent vascularity may cause the lesion to resemble a vascular anomaly on imaging. We report a 27-year-old man with a painful right shoulder mass of 4 years’ duration. Ultrasonography suggested a vascular malformation with possible thrombosis, while contrast-enhanced CT was interpreted as a vascular lesion. Complete excision was performed, and histopathology revealed the characteristic lobulated architecture, dual cell population, and focal ductal differentiation of eccrine spiradenoma. At 12-month follow-up, there was no clinical evidence of recurrence. This case shows that an adnexal tumor should remain in the differential for painful solid superficial masses despite conspicuous Doppler flow and enhancement. When imaging remains indeterminate, clinical correlation and histopathologic confirmation are important.