Mycobacterium tuberculosis in hepatic hilum as a cause of erythema induratum of Bazin.

Erythema induratum of Bazin (EIB) is a rare manifestation of cutaneous tuberculosis, typically associated with active tuberculosis infections. We present the case of a 75-year-old immunocompetent Spanish woman who developed nodular lesions on her lower limbs. Initial differential diagnoses included sporotrichosis, erythema nodosum, Sweet's syndrome, sarcoidosis, and tuberculosis. The cutaneous and hepatic hilum biopsy revealed necrotizing granulomatous lymphadenitis but only the last one tested positive for M. tuberculosis; no evidence of the pathogen was detected in the other clinical samples. The patient was diagnosed with EIB associated with tuberculosis in the hepatic hilum and successfully treated with a standard anti-tuberculosis regimen. This case underscores the importance of considering hepatic involvement in extrapulmonary tuberculosis and the diagnostic challenges it may pose in immunocompetent patients.