Delayed diagnosis of Ewing's sarcoma of the right humerus initially treated as chronic osteomyelitis: a case report.

We report a case of limited stage Ewing's sarcoma which was initially treated as chronic osteomyelitis for 3 years. A 24-year-old man presented with a one-week history of pain in the right arm and fever, with histology suggestive of osteomyelitis of the affected humerus. He developed multiple relapses of pain and fever; each episode responded to antibiotic treatment. A second biopsy was performed 3 years later and confirmed a diagnosis of Ewing's sarcoma. Despite a 3-year delay in diagnosis, the disease remained localised. This case report highlights an atypical facet of the natural history of Ewing's sarcoma: a response to antibiotic and anti-inflammatory agents, and the limited stage of the disease despite a misdiagnosis of 3 years. This suggests the possibility that anti-inflammatory agents exert an inhibitory effect on the tumour growth. We also highlight the newer histologic and immunologic staining used in the diagnosis of Ewing's sarcoma.