Cutaneous infection due to a rough variant of Mycobacterium marinum

Spreading lesions clinically resembling lymphangitic sporotrichosis developed on the right arm and chest of a 60-year-old man with chronic lymphocytic leukemia. Acid-fast bacilli were seen in exudates from lesions and in biopsies, and were cultured from them. The isolant grew initially as a yellowish-orange scotochromogen on Lowenstein-Jensen medium at room temperature and at 35 C., but failed to grow at 37 C. It failed to grow on 7-H-10 medium. On repeated subculturing over a 2-year period it gradually converted to a photochromogen. Histologically, there was ulceration with extensive acute and chronic inflammation with fibrosis. Organisms occurred intracellularly as dense, compact, cigar-like packets resembling lepara bacilli. The appeared to have a predilection for the nucleus. The patient was anergic to PPD S, B, Y and G, and lacked antibodies to BCG phosphoglycolipids. The mycobacteriosis was alleviated by combined INH and ethambutol therapy. The isolant was identified as a rough variant of Mycobacterium marinum. It may have been transmitted by an insect vector.