Huge cutaneous abscess and severe symptomatic hypercalcaemia secondary to Mycobacterium kansasii infection in an immunocompetent patient

Mycobacterium kansasii is among the most common non-tuberculous mycobacteria causing human infections. Apart from pulmonary infection, the most common infection caused by M. kansasii is skin and soft tissue infection, and it is very rare in immunocompetent people. In this report, we present a case of a huge cutaneous abscess caused by M. kansasii. A 63-year-old man living in Bangkok presented with progressive pain at the left lateral chest wall for 3 weeks and altered mentation for a few days. Examination revealed a non-tender fluctuated cutaneous mass 20x10 cm in size. An aspiration of the mass yielded 50 mL pus with many positive acid-fast bacilli. Mycobacterial PCR was positive for M. kansasii with culture confirmation. There was severe hypercalcaemia. The treatment included surgical drainage, and medical treatment consisted of isoniazid, rifampicin, ethambutol and levofloxacin, along with adequate hydration and calcitonin for hypercalcaemia. The patient gradually improved and was discharged 12 days after hospitalisation.