Cutaneous tuberculosis an unusual localization: A case report

Tuberculosis is a major public health concern. Morocco is a tuberculosis endemic country; nearly 30000 cases are recorded each year, pulmonary tuberculosis represents 57%, extrapulmonary tuberculosis 43%. Cutaneous localization is exceptional; it represents 0.5 to 2% of cases of tuberculosis. It is very difficult to diagnose, given the variability of clinical presentation, and is based on combining clinical, radiological and biological arguments. In this study we report a rare case of cutaneous tuberculosis occurring in a patient with history of pulmonary and cutaneous sarcoidosis, with personal history of pulmonary tuberculosis treated in 2017, presenting for a month a mass on the left thigh in the form of an abscess. The patient benefited from drainage of the skin abscess, the research of Koch's bacillus (BK) by conventional and molecular methods was positive. Direct examination remains a very simple and rapid tool, it allows the search for Acid-Fast Bacilli (AFB) in the sample, its sensitivity is variable, it does not exceed 20% for extra-pulmonary samples, and the detection threshold is order of 104 AFB of pathological product. Polymerase chain reaction (PCR) using the GeneXpert MTB/RIF method offers an early diagnosis that identifies Mycobacterium tuberculosis DNA and the main mutations that confer rifampicin resistance to the bacteria. Cutaneous tuberculosis is a rare entity, the polymorphism of the anatomo-clinical presentation and the multiplicity of differential diagnoses make the diagnosis difficult. The present case encourages us to think about it when faced with abscessed and recurrent skin lesions, especially in an endemic country like ours.