An unusual cause of knee pain discovered at a nurse practitioner clinic

To describe an interesting and instructive case of knee pain from nurse practitioner (NP) practice and discuss the epidemiology, pathophysiology, clinical evaluation, and treatment of osteosarcoma.

Findings from the history, physical examination, diagnostic testing, and follow-up of the case of an 18-year-old male who first presented with nontraumatic, diffuse left knee pain of 2.5-month duration.

At follow-up, after a trial of conservative treatment, a lesion suspicious for osteosarcoma was seen in the proximal tibia. Osteosarcoma is a rare but dangerous cause of chronic extremity pain, especially in children and adolescents.

NPs must consider malignant bone tumors in the differential diagnosis of traumatic and nontraumatic extremity pain of extended duration, especially in children and adolescents. Thorough, persistent follow-up on recommended tests and referrals is necessary to ensure that important findings are not missed. The care of uninsured patients requires particular attention to cost concerns and access issues.