We report the extremely uncommon case of a 77-year-old woman in whom a tumor found to be a melanotic schwannoma, arising from the right rectus abdominis muscle, was detected during investigation for a rheumatic disorder, finally identified as polymyalgia rheumatica (PMR). Tumors of this type most commonly occur in spinal nerve roots, and their clinical behavior is very difficult to predict. As far as we are aware, this is the first reported case affecting the aforementioned site. The challenging issue in this case concerns the possible link between the 2 clinical conditions, in particular the development of PMR as a paraneoplastic syndrome. Although such an association has not been reported, PMR is included among the rheumatic disorders reported to be associated with malignancies and occasionally with benign tumors. However, given that tumor resection did not result in remission of PMR and symptoms improved rapidly with prednisone, it seems likely that the above disorders might simply coexist.