Xanthoma simulating gouty tophus (case report of atypical cholesterol crystal deposition)

The most common clinical manifestation of hyperlipidemia is the formation of xanthomas, which are most often localized subcutaneously, sometimes involving tendons and ligaments, and are usually asymptomatic. A fairly rare manifestation of hyperlipidemia is hypercholesterolemic arthritis caused by cholesterol crystals. In this article, we present a case of atypical xanthoma formation in a patient in the area of the first metatarsophalangeal joint, which resembled a gouty tophus. Taking into account the presence of hyperuricemia in the blood and the “classic” lesion of the first metatarsophalangeal joint, gout was primarily suspected in the patient. The diagnosis of arthritis associated with cholesterol crystals was confirmed using the “gold standard” diagnosis of microcrystalline arthritis—crystal detection using polarization microscopy. This case gives a clear idea of how important it is not to rely solely on the clinical picture when diagnosing gout.