A 16-year-old boy with multifocal, painless osseous lesions.

A 16-year-old boy presented with left wrist pain of 8 months’ duration. There was a remote history of a hyperextension injury to the wrist while weight lifting. He denied all constitutional symptoms. He had taken NSAIDs intermittently with no resolution of symptoms. He was an otherwise healthy adolescent with no significant medical history. His family history was noncontributory. The patient had been seen by an orthopaedist who suspected triangular fibrocartilage complex (TFCC) tear and ordered MRI without contrast. The MRI showed several welldefined intramedullary lesions in the distal radius and carpal bones that were suggestive of leukemia. The orthopaedist then obtained a bone marrow biopsy which showed normocellular marrow with trilineage hematopoiesis and no evidence of acute leukemia. The patient then was referred for orthopaedic oncology evaluation for additional workup of the lesions seen on the MR images. On examination, the patient was a healthy-appearing teenager with stable vital signs. Focused examination of the wrist showed tenderness to palpation at the TFCC. Ulnar deviation of the wrist provoked ulnar-sided wrist pain. There were no palpable masses, deformities, swelling, or bony tenderness. He had no lymphadenopathy. The rest of his physical examination was normal. Laboratory examinations showed a slightly increased white blood cell count of 11.0 (10/L) with a differential of 61% neutrophils, 28% lymphocytes, 8.7% monocytes, 1.4% eosinophils, and 0.3% basophils. Erythrocyte sedimentation rate was increased at 35 mm/hour. Total protein electrophoresis was increased in the a1-globulin region to 0.56 g/dL (normal, 0.19–0.46 g/dL) and in the a2-globulin to 1.19 g/dL (normal, 0.48–1.05 g/dL). Plain radiographs of the wrist showed no abnormalities. Based on these imaging studies, further workup, including contrast enhanced MRI (Fig. 1), CT scan (Fig. 2) of the left wrist, and a whole-body bone scan (Fig. 3), were performed. Based on the history, physical examination, laboratory studies, and imaging studies, what is the differential diagnosis at this point? Each author certifies that he or she, or a member of his or her immediate family, has no commercial associations (eg, consultancies, stock ownership, equity interest, patent/licensing arrangements, etc) that might pose a conflict of interest in connection with the submitted article. All ICMJE Conflict of Interest Forms for authors and Clinical Orthopaedics and Related Research editors and board members are on file with the publication and can be viewed on request. Each author certifies that his or her institution approved the reporting of this case report, that all investigations were conducted in conformity with ethical principles of research, and that informed consent for participation in the study was obtained. This work was performed at The Mount Sinai Hospital/Mount Sinai School of Medicine Department of Orthopaedic Surgery.