Erythema induratum secondary to Pseudomonas aeruginosa bacteremia in an elderly patient: a rare case report

Mélissa M. de Carvalho, Department of Dermatology and Venereology, Hospital de Egas Moniz, Lisbon, Portugal Margarida M. Valejo-Coelho, Department of Dermatology and Venereology, Hospital de Egas Moniz, Lisbon, Portugal Rita Sampaio, Department of Pathology, Hospital de Egas Moniz, Lisbon, Portugal

Erythema induratum (EI) is a rare form of panniculitis, often associated with tuberculosis but which can be linked to other infections or idiopathic. We report a case of an atypical presentation of EI secondary to Pseudomonas aeruginosa bacteremia. An 84-year-old man with chronic kidney disease on hemodialysis was admitted for left leg cellulitis and Pseudomonas aeruginosa bacteremia. Despite antibiotic therapy, he developed nontender, erythematous nodules on his left leg. Histopathology revealed a mixed-pattern panniculitis consistent with EI. Targeted antibiotic therapy led to overall improvement. EI typically presents in adult women and rarely in elderly men. Differential diagnosis included infectious panniculitis, erythema nodosum and ecthyma gangrenosum. Negative microorganism stainingand a favorable antibiotic response confirmed the diagnosis. This case highlights a rare association of EI with infection by P. aeruginosa and emphasizes the importance of comprehensive diagnostic evaluation in atypical clinical presentations.

Keywords: Erythema induratum. Pseudomonas aeruginosa. Nodular vasculitis. Panniculitis.