Fine needle aspiration of tophi for crystal identification in problematic cases of gout. A report of two cases

BACKGROUND: The definitive diagnosis of gout is best established by demonstration of monosodium urate (MSU) crystals in the synovial fluid or biopsy. Fine needle aspiration cytology (FNAC) of tophi can play a crucial role in diagnosis. CASES: A 36-year-old chronic alcoholic male developed subcutaneous nodules on both malleoli without a history of arthropathy and with normal serum uric acid levels. FNAC of the nodules demonstrated stacks and sheaves of needle-shaped crystals of MSU. A 50-year-old diabetic male developed multiple nodules on the feet. He gave a past history of painful athropathy. A roentgenogram of the feet was suspicious for gout; however, joint aspiration failed, and the serum uric acid levels were normal. At this juncture FNAC of the feet tophi clinched the diagnosis of gout. In both cases, polarization of needle washings (wet mount) and the fixed, Papanicolaoustained smears showed negatively birefringent, needle-shaped crystals of MSU, thus confirming the diagnosis of gout. CONCLUSION: FNAC of gouty tophi is an easy alternative to synovial biopsy and joint fluid analysis. It is simpler, easier and less painful. As crystals are preserved in stained smears, they can be employed for polarization and confirmation of gout.