Xanthogranulomatous osteomyelitis of ulna mimicking neoplasm

Abstract

Background: Xanthogranulomatous osteomyelitis often presents as a severe chronic inflammation associated with pain, fever, and leukocytosis. It may mimic carcinoma in the involved organs.

Case presentation: A 50-year-old post-menopausal woman presented with a 2 year history of increasing swelling in the extensor aspect of her right forearm. Plain X-ray revealed an ill-defined expansile osteolytic lesion in the diaphysis of ulna. The gross, microscopic and ultrastructure findings of the curettage specimen was consistent with xanthogranulomatous osteomyelitis.

Conclusion: This case highlights the rare occurrence of xanthogranulomatous osteomyelitis involving ulna, which can mimic as a primary or secondary bone tumors. A correct diagnosis can only be made on histopathological examination.

Figure 1

X-ray of postero-anterior and lateral view of right forearm showing an expansile lytic destructive lesion involving mid one-third of diaphysis of ulna, with ill-defined zone of transition.

Figure 2

Light microscopy showing diffuse collection of foamy macrophages with nodular aggregates of lymphocytes (H&E, × 25). Inset: Higher magnification shows foamy macrophages having distinct cytoplasmic border, abundant pale granular cytoplasm and small pyknotic nucleus (H&E, × 240).