Cutaneous tuberculosis confirmed by PCR in a patient with culture negative for mycobacterium tuberculosis

ABSTRACT

Cutaneous tuberculosis is an old and rare infectious disease. Laennec reported the first case of cutaneous tuberculosis in 1826 and M.tuberculosis was discovered by Koch in 18821. Since then, many cases of cutaneous tuberculosis have been described and classified. The different forms of diseases correlate with the immunologic status of the host, host’s prior sensitization, route of disease transmission, layer of skin primarily involved and rate of disease progression. Nevertheless, the most widely accepted classification is based on the mechanism of disease propagation which can be via direct inoculation, through contiguous infection or via hematogenous route2. Bacterial load has also been used to categorize this disease into multibacillary and paucibacillary forms. Diseases under the multibacillary forms include primary inoculation tuberculosis (tuberculous chancre), scrofuloderma, tuberculous perioficialis, acute miliary tuberculosis and tuberculous gumma. Paucibacillary forms include lupus vulgaris, tuberculosis verrucosa cutis and tuberculids. Strains of M. Tuberculosis complex that can be isolated include M.tuberculosis, M. africanum, M. canetti and M. bovis, M. microti and M.bovis BCG.