Erythema Induratum (Nodular Vasculitis) of the Lower Extremities Without Tuberculosis in Psoriasis on Secukinumab (Interleukin 17A Inhibition): A Case Report

TL;DR

A patient with psoriasis developed a skin condition resembling tuberculosis but without TB, and was successfully treated with anti-inflammatory therapy.

Contribution

This case report highlights a non-tuberculous presentation of erythema induratum and the effectiveness of individualized anti-inflammatory treatment.

Findings

The patient's condition was confirmed as erythema induratum/nodular vasculitis without evidence of tuberculosis.

Treatment with prednisone and colchicine led to resolution of symptoms.

The case emphasizes the need for multidisciplinary care and avoiding unnecessary antituberculous therapy when diagnostics are negative.

Abstract

Erythema induratum/nodular vasculitis (EI/NV) classically associates with tuberculosis (TB), yet TB-negative disease is increasingly recognized in low-prevalence settings. A 58-year-old nurse with palmoplantar psoriasis controlled on secukinumab developed 6-8 months of exquisitely tender, ulcerating lower-leg nodules refractory to multiple antibiotics. Cultures were largely unrevealing; TB testing and broad microbial cell-free DNA were negative. Incisional biopsies showed lobular panniculitis with mixed inflammation and focal vasculitis, consistent with EI/NV; special stains/PCR for mycobacteria were negative. Multidisciplinary management included brief targeted Gram-positive coverage, high-dose prednisone taper, temporary cessation of IL-17 blockade, and transition to colchicine for steroid-sparing control. Within weeks, no new lesions appeared, and prior ulcers healed. This case underscores the importance of clinicopathologic correlation, rigorous infectious exclusion, and coordinated dermatology - infectious diseases - rheumatology care, favoring individualized anti-inflammatory therapy over empiric antituberculous treatment when TB risk is low and diagnostics are negative.

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