Disseminated Mycobacterium genavense infection in a healthy boy

Mycobacterium genavense (M genavense) has been recognized as a life-threatening pathogen in severely immunocompromised patients. To our knowledge, disseminated M genavense infection has never been described in immunocompetent individuals. Here, we report a case of disseminated M genavense infection in a healthy Japanese boy. A 15-year-old boy who had never been diagnosed with an immunodeficiency disorder was hospitalized because of ileus. Tumorous lesions were identified in the ileum, cecum, and ascending colon, resulting in stenosis of ileocecal valve. There was diffuse proliferation of histiocytes throughout the intestinal wall, along with lymphocytic infiltration. No nuclear or cellular atypia was present in these cells. Ziehl-Neelsen staining revealed numerous acid-fast bacteria in histiocytes. After surgery, systemic lymph node swelling was noticed by generalized examination, including the mesenteric and cervical lymph nodes. M genavense DNA was identified by direct sequencing of 16S ribosomal DNA that had been amplified by polymerase chain reaction.