Natural course of desmoid-type fibromatosis

Background. Desmoid-type fibromatosis is a locally aggressive tumor known to have high potential for local recurrence after resection, while it exhibits self-limiting behavior and shows growth arrest or spontaneous regression in many patients. Thus, its natural course is not well known, and the proper treatment has not yet been established. Methods. We retrospectively reviewed clinical outcome and changes in tumor size in 11 consecutive patients with extremity and trunk desmoid-type fibromatoses, who were basically observed without any treatment after diagnosis. Results. For two patients in whom the tumors were initially incorrectly diagnosed as other tumors, surgical resection was performed. For another two patients, surgical resections were performed in the follow-up periods due to tumor enlargement or joint contracture. In all four patients who underwent surgery, tumors recurred shortly after resection and re-resection was not performed. During the follow-up periods with a median length of 56 months, ten tumors eventually stopped growing, and three of them regressed spontaneously. At the time of final follow-up, ten patients were alive with residual disease without severe morbidity. In one patient, the tumor enlarged to over 30 cm in diameter with a substantial functional deficit. Conclusions. Simple observation is a noninvasive and function-preserving treatment for desmoid-type fibromatosis.