Atypical Morphology of a Typical Mycobacterial Infection

A-24-year-old woman reported with asymptomatic facial lesions present for 6 months. Examination revealed two closely located nodules which were firm, nontender, slightly erythematosus with crusting over the left cheek (Figure 1A). There was no regional lymphadenopathy, and the systemic examination was within normal limits. The differential diagnosis included cutaneous leishmaniasis, keratoacanthoma, and basal cell carcinoma. Tissue smear from nodules failed to reveal Leishmania donovan bodies. The histopathologic examination revealed nonca-seating epithelioid granulomas with lymphocyte cuffing in the dermis (Figures 2A and 2B). Special staining performed with Ziehl-Neelsen and Periodic acid-Schiff (PAS) stains was negative. Tissue cultures for bacteria, mycobacteria, and fungi were also negative; however Mantoux test (MT) performed for latent tuberculosis was strongly positive. Sputum for acid fast bacilli was negative, and serology for human immuno-deficiency virus (HIV)-1 and HIV-2 was nonreactive. A chest x-ray and ultrasound of the abdomen did not reveal any abnormality. Although the morphology of skin lesions did not favor classic lupus vulgaris (LV), considering the endemicity of tuberculosis in India, positive results of Mantoux test, and a dermal epithelioid granuloma, the patient was prescribed antitubercular therapy (ATT), comprising isoniazid, rifampicin, ethambutol, and pyrazinamide. Dramatic response was observed after 2 months, and complete healing with residual scarring took place in next 4 months (Figure 1B).