Nodular hidradenoma is a rare benign adnexal tumor originating from the sweat glands, which clinically presents as a tumor mimicking primary or metastatic malignant lesions. Dermoscopy, as well as clinical characteristics, reveals structural patterns that allow for broad differential diagnoses. Dermatological ultrasonography has become a scientifically recognized diagnostic tool to enable early and accurate diagnosis of hidradenoma, supporting surgical treatment and histopathological analysis. This study reports a rare case of nodular hidradenoma, highlighting the diagnostic innovation achieved through low-frequency ultrasonography, which includes clinical, radiological, and histopathological characteristics.

Keywords: Skin neoplasms; Ultrasonography; Diagnostic imaging; Clinical diagnosis