Identifying tophaceous gout in foot ulcers using ulcer debris microscopy in Type 2 diabetes

What is it about?

Gout is frequently underdiagnosed in patients with diabetes. As a chronic disease characterised by urate deposition, gout can lead to the formation of tophi in the feet, which may ulcerate. However, the prevalence of tophaceous gout in patients with diabetes and foot ulcers has not been previously studied. This study explored the feasibility of sampling foot ulcer debris for polarised light microscopy to detect birefringent urate crystals and identify cases of gout in patients with diabetes. Among 36 ulcer debris samples examined, urate crystals were identified in five cases (14%) strongly suggesting previously unrecognised gout. Radiographic findings further supported tophaceous gout as the primary cause of these foot ulcers. These findings indicate that unrecognised tophaceous gout may be relatively common among patients with Type 2 diabetes and foot ulcers. However, selection bias may have led to an overestimation of prevalence, while insufficient or contaminated samples may have resulted in an underestimation. Further refinement of sampling and examination techniques—ideally supplemented by imaging prior to ulcer treatment —is needed to improve the detection of all cases with urate crystals and to ensure that negative findings truly reflect the absence of gout rather than technical limitations.

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