The role of Mycobacterium tuberculosis in the etiology and pathogenesis of cutaneous tuberculosis is controversial because of the difficulties associated with demonstrating the presence of these mycobacteria in tuberculid cutaneous lesions by routinely available microbiological and histological techniques. In this study, we aimed to demonstrate the presence of M. tuberculosis in cutaneous tuberculosis. Multiple polymerase chain reaction (PCR) followed by nested PCR was used to amplify genomic fragments from 3 different mycobacteria species. DNA was isolated from 30 paraffin-embedded skin biopsies. Samples were selected randomly from patients with a clinical and histopathological diagnosis of the most frequent groups of cutaneous tuberculosis in Mexico as follows: 5 cases of scrofuloderma tuberculosis; 2 cases of lupus vulgaris tuberculosis; and 5 cases of tuberculosis verrucosa cutis. The other cases denominated tuberculids in some countries such as Mexico and included the following: 7 cases of rosacea-like tuberculosis; one case of papulonecrotic tuberculosis; and 10 cases of erythema induratum of Bazin. Four normal skin biopsies were included as controls. M. tuberculosis DNA was amplified successfully by nested PCR in 80% of the samples (24 of the 30 samples) assayed. Mycobacterial DNA was not detected in the normal skin biopsies used as controls. Detection of M. tuberculosis DNA in 80% of cutaneous tuberculosis analyzed implicates this mycobacterium in the pathogenesis of multiple clinical forms of cutaneous tuberculosis.
*Laboratorio de Investigación en Inmunología y Proteómica, Unidad de Hemato-Oncología, Hospital Infantil de México Federico Gómez, Mexico City, México;
†Departamento de Patología, Centro Dermatológico “Dr. Ladislao de la Pascua,” Secretaría de Salud, Mexico City, México;
‡Unidad de Investigación en Enfermedades Infecciosas, Hospital de Pediatría, Centro Médico Nacional SXXI, Mexico City, México;
§Departamento de Ciencias de la Salud, Laboratorio de Biología Molecular, Universidad Autónoma Metropolitana, Mexico City, México; and
¶Unidad de Investigación Médica en Inmunoquímica, Hospital de Especialidades, Centro Médico Nacional SXXI, IMSS, Mexico City, México.
Correspondence: Carmen Maldonado-Bernal, PhD, Laboratorio de Investigación en Inmunología y Proteómica, Unidad de Hemato-Oncología, Hospital Infantil de México Federico Gómez, Dr. Márquez 162, Col. Doctores, C.P. 06720, CDMX, México (e-mail: firstname.lastname@example.org).
Supported by Coordinación de Investigación Médica, Instituto Mexicano del Seguro Social (IMSS).
The authors declare no conflicts of interest.