The role of high-frequency ultrasound in the evaluation of an acral subcutaneous nodule: a case report and literature review

Acral subcutaneous nodules pose a diagnostic challenge due to their broad differential diagnoses. We report a case of a foreign body granuloma presenting as a long-standing acral subcutaneous nodule on the thumb of a 64-year-old woman. High-frequency ultrasound revealed a homogeneous hypoechoic nodule with posterior acoustic enhancement, surrounding a central linear hyperechoic structure suggestive of a foreign body reaction. Excisional biopsy confirmed a granulomatous inflammatory process surrounding a vegetal fiber. This case highlights the value of high-frequency ultrasound as a noninvasive tool to support etiological diagnosis and guide surgical planning in chronic acral subcutaneous nodules.

Keywords: Ultrasonography; Granuloma, Foreign-Body; Epidermal Cyst