Chronic Bilateral Thigh and Knee Discomfort in an 18-year-old Man

Abstract

An 18-year-old man presented with severe, intermittent bilateral thigh and knee pain of approximately 6 months' duration. His symptoms had initially manifested as localized anterior left knee pain 2 years earlier, and he had been treated with high-dose ibuprofen and physical therapy for the presumptive diagnosis of patellofemoral syndrome. Despite attempts at nonoperative management, he had experienced progressive discomfort involving the left thigh, right knee, and right thigh. At the time of presentation, he described pain principally in the left thigh, characterized as self-remitting and without clear antecedent. He also noted long-standing night pain interfering with sleep but denied any fevers, chills, rigors, weight loss, or other constitutional symptoms. A review of systems was otherwise negative, and medical history was unremarkable.Physical examination revealed mildly shortened stance phase with respect to the left lower extremity; the patient noted his limp had been more pronounced during the preceding month. Pelvic compression and palpation along the spinal column and long bones of the lower extremities elicited no focal tenderness. No visible lesions or palpable masses were observed in the trunk or upper or lower extremities. Active and passive range of motion of the hips and knees were full and well tolerated. The patient was neurologically intact with normal sensation to light touch and full motor strength in all muscle groups.Laboratory studies revealed normal white blood cell count Plain radiographs of the left femur (Fig. 1), computerized tomography (CT) scan of the pelvis and bilateral femora, radionuclide scan (Fig. 2), and magnetic resonance imaging (MRI) of the right acetabulum and bilateral femora (Fig. 3) were obtained.Based on the history, physical examination, and imaging studies, what is the differential diagnosis? Imaging InterpretationRadiographs of the left femur (Fig. 1) revealed an osteolytic lesion extending from the intertrochanteric region to the middiaphysis. The lesion demonstrated mild bony remodeling and cortical thickening most evident in the diaphysis with a well-defined proximal margin.A noncontrast CT scan performed through the pelvis and bilateral femora demonstrated multifocal osteolytic lesions in the left femur, right femur, and superior right Each author certifies that he or she has no commercial associations (e.g., consultancies, stock ownership, equity interest, patent/licensing arrangements, etc.) that might pose a conflict of interest in connection with the submitted article. Each author certifies that his or her institution has approved or waived approval for the reporting of this case and that all investigations were conducted in conformity with ethical principles of research.