OBJECTIVE: The purpose of the present study was to determine the local recurrence rate, risk of dedifferentiation, and distant metastasis after surgical excision of intramuscular lipomas (IML) and atypical lipomatous tumors (ALT).

SUBJECTS AND METHODS: We retrospectively assessed all IML and ALT surgically removed from the extremities or trunk wall in our clinic between 1997 and 2006. Data from 141 patients with IML and 35 patients with ALT were extracted from the National Pathology Registry and patient files.

RESULTS: IML and ALT recurred in 10 and 6 tumors, respectively. No metastases were observed in either group. The 5- and 10-year local recurrence-free survival rates were 97.1% (94.3-99.9) and 94.8% (CI: 91.1-98.6) for IML and 84.6% (CI: 72.1-97.1) and 81.1% (CI: 67.6-94.8) for ALT, respectively. ALT were found to dedifferentiate in 2/35 cases.

CONCLUSION: Both IML and ALT showed a low recurrence rate when removed surgically from the extremities or trunk wall with intended marginal resection. No distant metastases were observed in any of the groups. It, therefore, seems safe to treat these tumors with marginal resection.