Mycobacterium leprae from a Skin Infection

An adult male from Mexico was referred to a dermatology clinic for a rash and nodules on his arms, legs and trunk, with background erythema and swelling of the lower legs. The nodules were 5 to 10mm in size, and some were somewhat ulcerated. The skin changes started approximately six to eight months previous, and were accompanied by some weight loss. The patient had no history of exposure to TB, and remembered a recent negative PPD test. H&E and special stains, as well as fungal and AFB cultures were set up from a tissue biopsy taken from his right thigh. A section of tissue was also sent to the Microbiology Molecular Diagnostics lab at the UWMC for PCR testing for atypical mycobacteria.

The fungal culture was negative, while an Auramine-O stain showed 4+ acid-fast bacilli. Direct tissue extraction and PCR amplification of the RNA polymerase (rpoB) gene fragment produced a DNA sequence matching 100% to Mycobacterium leprae in the NCBI nucleotide database.

The patient was directed to return to his primary care physician for treatment with minocycline and dapsone, and regular CBC monitoring.

Please refer to Available Tests for more information about TSEXAM for AFB.