Background: A 64-year-old woman presented with erythematous plaques, tender nodules, and pustules of the dorsal right hand and both legs following long-term treatment with systemic steroids and infliximab. Skin biopsy demonstrated dermal inflammation with foci of necrosis and multinucleated giant cells containing fungal spores. Tissue culture grew Trichophyton rubrum. Objective: To report a case that demonstrates the pathophysiology of invasive T. rubrum infection, the mechanisms of action and uses of tumor necrosis factor α (TNF-α)-inhibiting drugs, and how these drugs may increase patients' risk of invasive dermatophytosis. Conclusion: Dermatophytes such as T. rubrum rarely cause invasive disease. This unusual presentation of invasive T. rubrum occurred with immunosuppression by infliximab and systemic steroids. Patients should have a thorough examination for signs of latent infection before TNF-α inhibitors are prescribed, including inspection of the skin and nails for signs of dermatophytosis.
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