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Erythema induratum (EI) is a chronic lobular panniculitis with vasculitis. Historically, EI was associated with Mycobacterium tuberculosis (MTB) infection while the term “nodular vasculitis” (NV) was used when other non-MTB infectious etiologies, autoimmune connective tissue diseases, malignancies, or medications were implicated. Today, EI and NV are often used synonymously. EI/NV classically presents as tender erythematous or violaceous ulcerated plaques and nodules on the posterior lower legs of young women. All patients with clinical features suggestive of EI/NV should have a full thickness punch or incisional biopsy of involved skin sent for histologic examination as well as bacterial, mycobacterial and fungal culture. Quantiferon gold test is also important to rule out MTB infection, as cultures may be negative when MTB is latent within adipocytes and PCR is not always feasible.1,2 Therapy is based on the underlying etiology and severity. For mild cases, NSAIDs, rest, and compression and elevation are helpful adjuncts. It is this author’s opinion that exclusion of MTB infection is of utmost importance and a multidrug MTB treatment regimen is preferable given bacterial resistance and risk of reactivation in those who are immunosuppressed. If multidrug resistant MTB is encountered, the authors recommend referral to infectious disease for further management. See Table 60-1.
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