An Unusual Acral Swelling: Histopathological Confirmation of Superficial Acral Fibromyxoma

Superficial Acral Fibromyxoma (SAF) is an uncommon, benign mesenchymal neoplasm that predominantly involves the subungual and periungual soft tissues of the digits. Its indolent growth, painless nature, and non specific clinical features often lead to misdiagnosis, resulting in delayed treatment or inappropriate management. The present case described a 36-year-old male who presented with a decade-long history of a gradually enlarging, painless mass on the distal phalanx of the right ring finger, followed by a recent phase of accelerated growth over two months. Magnetic Resonance Imaging (MRI) demonstrated a well-circumscribed, T2-hyperintense lesion without underlying osseous involvement. Complete surgical excision was performed. Histopathological evaluation revealed a proliferation of bland spindle and stellate fibroblastic cells embedded in a fibromyxoid stroma, without evidence of cytologic atypia or mitotic activity. Immunohistochemical analysis showed diffuse positivity for CD34 and vimentin, with negative staining for S-100 and Epithelial Membrane Antigen (EMA), supporting the diagnosis of SAF. The postoperative course was uneventful, and there has been no evidence of recurrence to date. Given the potential for local recurrence, especially in incompletely excised lesions, accurate diagnosis through histopathology and Immunohistochemistry (IHC) is essential. Awareness of SAF's distinguishing features among clinicians, radiologists, and pathologists can aid in timely diagnosis, reduce the risk of misclassification, and facilitate appropriate surgical management, ultimately improving patient outcomes.