The cytologic diagnosis of joint and articular surface-based lesions traditionally has been accomplished by examination of fluids or effusions. Although exfoliative cytology remains an accurate diagnostic test, not all joint-based lesions will produce effusions that are amenable to this type of examination. Fine-needle aspiration (FNA) represents an excellent alternative to traditional cytologic or histologic methods of diagnosis in joint pathology.
The authors reviewed FNA materials for the period 1992-2001 from lesions of joint spaces and periarticular soft tissues. All diagnoses based on cytologic materials that were included in this study were confirmed with histologic follow-up. Cytologic and histologic materials were prepared using standard methods.
The authors found six relatively common lesions that were amenable to diagnosis by FNA. These included rheumatoid nodule, gouty tophi, ganglion cysts, pigmented villonodular synovitis, synovial chondromatosis, and synovial sarcoma. There are potential pitfalls in discriminating gout from pseudogout and synovial chondromatosis from chondrosarcoma.
In most instances, mass-producing lesions of the joint space or the periarticular soft tissues can be diagnosed successfully by FNA. The common lesions are easily recognizable and are cytologically distinctive.