Poor prognosis infantile fibrosarcoma with pathologic features of malignant fibrous histiocytoma after local recurrence.

In a retrospective study of infants under 1 year of age treated at our institution over a 30-year period for soft tissue tumors, eight fibrosarcomas (FS) were seen, six of which were congenital. Therapy consisted of local excision (n = 3), radiotherapy (n = 1), surgery + radiotherapy (n = 1), surgery + chemotherapy (n = 1), and surgery + chemotherapy + radiotherapy (n = 2). Among these eight patients, four are alive in first complete remission (CR) with 13, 17, 23, and 27 years of follow-up. Of the remaining four patients, two had local recurrences and are still alive in CR after re-excision of the tumor, while the other two had both local and distant relapses and died. Interestingly, in the two patients who developed distant metastases, the pathologic pattern was that of malignant fibrous histiocytoma (MFH) at the time of local recurrence. To our knowledge, no similar cases of transitions between infantile FS known for its favorable outcome and MFH have been reported in this age group. The relevance of such transitions is difficult to assess. However, given the known metastatic potential of MFH, we believe that chemotherapy regimens currently used in the management of childhood soft tissue sarcomas should be used in similar cases.