Monoarthritis, characterized by inflammation of a single joint, often presents with symptoms mimicking septic arthritis, necessitating prompt diagnosis.
Ewing sarcoma, a rare malignant bone tumor, typically affects long bones and can present with varied clinical manifestations.
Observation:
A 22-year-old female patient presented with monoarthritis, initially suspected to be septic arthritis due to purulent synovial fluid.
Synovial biopsy revealed chronic synovitis, but further analysis of the synovial fluid identified malignant cells.
Findings:
The malignant cells in the synovial fluid were confirmed to originate from a Ewing sarcoma of the distal femur.
This case highlights the diagnostic challenge where a bone malignancy presented as an isolated joint inflammation.
Implications:
Malignancy should be included in the differential diagnosis for unexplained monoarthritis, especially when septic arthritis is suspected but not confirmed.
This case underscores the importance of comprehensive analysis of synovial fluid, including cytological examination for malignant cells, in atypical presentations of joint inflammation.