Gouty Tophi of the Fingertips Induced by Repeated Microtrauma

A 79-year-old male with a medical history relevant for type 2 diabetes mellitus, chronic kidney disease, and asymptomatic hyperuricemia presented a 1-year lesion on the distal phalanx of the third finger of the left hand. Physical examination revealed erythematous-to-violaceous swelling of the distal phalanx, accompanied by yellowish-white nodules and ulcerations. Radiography showed no abnormalities. The lesion corresponded to a site frequently used for capillary glucose monitoring. Histopathological examination of a skin biopsy revealed amorphous eosinophilic deposits in the dermis associated with a foreign-body type granulomatous reaction. A diagnosis of gouty tophus of the distal phalanx, possibly precipitated by repeated microtrauma, was established. Hyperuricemia is a necessary condition for gout development, but only a minority of hyperuricemic individuals will develop clinical manifestations [1]. Several factors have been described influencing crystal deposition, such as temperature, pH, changes in urate levels and local trauma [2]. Previous cases have been reported of tophi formation in atypical locations following trauma [3]. In patients with long-standing asymptomatic hyperuricemia, repeated low-grade trauma may lead to localised deposition of monosodium urate crystals. Clinicians should consider atypically located tophaceous gout as a result of a Koebner-like phenomenon, particularly in areas subjected to repeated microtrauma, such as capillary puncture sites (Figure 1A–C). All authors of the manuscript have cooperated in the elaboration of the manuscript and its revision process. All patients in this manuscript have given written informed consent for participation in the study and the use of their deidentified, anonymized, aggregated data and their case details (including photographs) for publication. Ethical approval: The patient consented the use of his information and images after appropriate anonymization of all data. No approval by the Ethical Institutional Board was needed. The authors declare no conflicts of interest. Data available on request due to privacy/ethical restrictions. Complete clinical data is available upon request to the corresponding author.