Superficial acral fibromyxoma: a clinicopathological analysis of 32 tumors including 4 in the heel.

Aims: To examine a series of superficial acral fibromyxomas (SAFs) and discuss our experience with this new entity and its differential diagnosis in the past 5 years.

Methods And Results: Thirty-two new cases of SAF were studied between 2001 and 2006. The patients included 22 males and 10 females with an age range between 23 and 82 years (mean 51, median 53) presenting with a solitary mass or nodule with an average size of 2 cm. The sites were the toes (n = 15) and fingers (n = 13) with 66.6% of tumors close to or involving the nail bed. Four tumors occurred in the heel where SAF has not been previously observed. Local recurrences developed in 3 of 14 patients (22%). Histologically, all tumors presented with spindle cells with a vague storiform and fascicular pattern embedded in a myxoid/fibromyxoid/collagenous stroma. A characteristic immunophenotype included CD34+, CD99+/- and EMA+ focally. One case showed moderate cytological atypia with 1 mitosis per 10 HPF, but a 4-year follow up showed no evidence of recurrence.

Conclusion: Thirty-two new cases of SAF confirm this tumor as a reproducible entity. Occurrence in the heel, a new site for this tumor, was reported in four cases. Recurrence rate of this tumor may exceed 20%.