Acral Fibrochondromyxoid Tumor: Diagnostic Challenges and Multimodal Characterization in a Hand Mass Case.

Acral fibrochondromyxoid tumor (AFCMT) is a rare and recently characterized matrix-rich soft tissue occurring on acral sites. Here, we conducted a multi-dimensional analysis of AFCMT that occurred in the hands from clinical, image, pathological, and molecular perspectives, and discussed its clinicopathological features and diagnostic strategies. In general, the hand appears as a clearly demarcated lump. In the image, scattered calcifications can be observed, along with the proliferation of mucinous cartilage matrix. Microscopically, pale eosinophilic chondrocyte-like cells are suspended within the abundant chondromyxoid matrix. The tumor cells showed immunoreactivity for CD34, ERG, SOX9 and Vimentin, supporting mesenchymal lineage differentiation. Interestingly, transcriptome-wide sequencing identifies the characteristic THBS1::ADGRF5 gene fusion, further clarifying its molecular signature. AFCMT is frequently underrecognized due to its rarity, nonspecific clinicoradiological features, and histological overlap with other fibromyxoid or cartilaginous lesions. This case highlights the importance of multimodal diagnostic strategies, improving multidisciplinary awareness and management capabilities of soft tissue tumors.