Conditions that mimic bone or soft-tissue tumours are relatively common but may be overlooked in the differential diagnosis of a soft-tissue mass or bone lesion. Such conditions include hematoma and infection. We describe 2 patients who presented with bone and soft-tissue lesions that were not neoplastic.
A 31-year-old man with a history of intravenous drug abuse presented with spontaneous onset of flank pain associated with a mass. Axial computed tomographic images of the pelvis (Fig. 1) showed a heterogeneous right-sided soft-tissue mass involving the ilipsoas muscle and displacing small bowel, blood vessels and urinary bladder. A biopsy was performed, and a large hematoma was evacuated. Histologic examination of the specimen did not reveal evidence of malignant cells.
Axial computed tomographic scan of the pelvis.
A 20-year-old man presented with a 6-month history of pain in the arm, weight loss and general malaise. On examination he had a tender mass anterior to the right shoulder associated with axillary lymphadenopathy. Radiographs showed aggressive features in the diaphysis with endosteal erosion, periosteal reaction and cortical destruction (Fig. 2). Gadolinium-enhanced magnetic resonance imaging confirmed the lesion seen on the plain film and on T1-weighted imaging showed enhancing soft-tissue septae and low signal material within the medullary cavity in keeping with necrotic debris. In addition, an enhancing extraosseous soft-tissue abnormality was demonstrated along the proximal metaphysis and diaphysis (Fig. 3). Imaging of the proximal humerus confirmed lymphadenopathy and an effusion of the glenohumeral joint (Fig. 4).
Plain radiograph of the right humerus.
Sagittal T1-weighted magnetic resonance image after gadolinium enhancement.
Axial T2-weighted magnetic resonance image of the glenohumeral joint.
The differential diagnosis included Ewing’s sarcoma. At biopsy, the humeral shaft was opened using a small curette, and a large volume of purulent fluid under pressure was released. The canal and wound were irrigated with saline. Staphylococcus aureus was grown from cultures of the fluid. The patient’s symptoms resolved after intravenous treatment with antibiotics.
Footnotes
Section Editor: Robert S. Bell, MD
Submissions to Surgical Images, musculoskeletal section, should be sent to Dr. Robert S. Bell, University Musculoskeletal Oncology Unit, Ste. 476, 600 University Ave., Toronto ON M5G 1X5; fax 416 586-8397.