Distinct histopathological patterns in single lesion leprosy patients treated with single dose therapy (ROM) in the Brazilian Multicentric Study.

This paper aims to describe the histomorphologic features of skin biopsies of single lesion leprosy patients recruited at outpatient clinics in four Brazilian states in the Northeast (Amazonas and Rondonia), Southeast (Rio de Janeiro) and Center-West (Goiás) between October 1997 and December 1998. Patients clinically diagnosed as single skin lesion paucibacillary (SSL-PB) leprosy had a standard 4-mm punch biopsy taken from the lesion before rifampin, ofloxacin, minocycline (ROM) therapy. The features of the cellular inflammatory infiltrates, the presence of nerve involvement and acid-fast bacilli (AFB) were used to categorize SSL-PB biopsies into different histopathological groups. Two-hundred-seventy-eight (93.0%) out of 299 patients had a skin biopsy available. Seven single lesion patients were diagnosed as BL or LL leprosy types (MB) by the histopathological exams and 12 cases were excluded due to other skin diseases. Therefore, 259 patients had skin lesions with histomorphological features compatible with PB leprosy categorized as follows: 33.6% (N = 87) of the biopsies represented well-circumscribed epithelioid cell granuloma (Group 1); 21.6% (N = 56) less-circumscribed epithelioid cell granuloma (Group 2); 12.0% (N = 31) were described as mononuclear inflammatory infiltrate permeated with epithelioid cells (Group 3), and 29.7% (N = 77) had perivascular/periadnexal mononuclear inflammatory infiltrate (Group 4). Minimal/no morphological alteration in the skin was detected in only 8 (3.1%) SSL-PB patients categorized as Group 5, who were considered to have leprosy by clinical parameters. SSL-PB leprosy patients recruited in a multicentric study presented histomorphology readings comprising the whole PB leprosy spectrum but also a few MB cases. These results indicate heterogeneity among SSL-PB patients, with a predominance of well-circumscribed and less-circumscribed epithelioid cell granulomas (Groups 1 and 2) in the sites studied and the heterogeneity of local cellular immune response.