Unsuspected metastases presenting as solitary soft tissue lesions: a fourteen-year review

Objective. To describe a series of patients with no known primary malignanc y who presented with a solitary unsuspected soft tissue metastasis masquera ding as a soft tissue sarcoma, and secondarily to describe the imaging appe arance of these lesions. Design. Records of two academic hospitals with active orthopedic oncology s ervices were reviewed for patients meeting the above criteria. Clinical cha rts were examined, and the imaging appearance of the soft tissue lesions re trospectively reviewed. Patients. Of 1421 patients examined for soft tissue lesions, 11 were found who met the above criteria. Results. Of the 11 patients whose initial presentation was a solitary soft tissue metastasis, eight were found to have a primary lung cancer, two were diagnosed with adenocarcinoma of unknown primary, and adenocarcinoma of th e colon was discovered in the remaining patient. Conclusions. The clinical presentation of a solitary soft tissue metastasis without a known primary malignancy is a rare occurrence, with an incidence of approximately 0.8%. Lung cancer is the primary neoplasm in a high perce ntage of these cases.