[Infiltrating intramuscular lipoma]

Intramuscular lipomas are rare, benign unencapsulated tumors. They are also called infiltrating lipomas because of their infiltrative growth pattern which, deeply localized, seizes the skeleton muscle. The only obvious symptom is a palpable mass. Microscopically, monovacular fat tissue shows up between the muscle fiber. In extreme cases the preexisting muscle can be totally replaced by fat tissue. A precise pathohistological examination is needed to avoid the mistaken diagnosis of a well-differentiated liposarcoma. Late diagnosis, the extent and the localization of the tumor often do not allow for an R0 resection and influence the postoperative recurrence rates, which lie between 3 and 62%. R0 resections are not desirable when postoperative severe loss of function can be expected. Malfunctions will slowly take place and can greatly be compensated, in contrast to a radical procedure with immediate loss of function.