Fine-needle aspiration cytology finding uric acid crystals produced by Aspergillus

Uric acid is a metabolic product of nucleic acid and protein. Hyperuricemia results from failure or lack of urate oxidase. We present a case of a 61-year-old man with a painless forearm swelling, from which uric acid crystals were found on cytology. There were also septate fungal hyphae with morphology of Aspergillus, which has the source of the uric acid. Serum uric acid levels in our patient were normal.