Mycobacterium marinum: a rare cause of chronic lymphocutaneous syndrome.

We investigated the prevalence of Mycobacterium marinum lymphadenitis and describe 4 children with the disease. The database of the microbiology laboratory of a tertiary pediatric medical center was searched for all cases of nontuberculous mycobacterial lymphadenitis from 1996 to 2016. M. marinum lymphadenitis was defined as isolation of the pathogen from a lymph node or from a skin lesion with an enlarged regional lymph node. M. marinum was isolated from lymph nodes in 2 of 167 patients with nontuberculous mycobacterial lymphadenitis and from skin lesions in 2 children with skin lesions and regional reactive lymphadenitis, yielding a 2.4% prevalence of M. marinum lymphadenitis. All 4 affected children were younger than 7 years and had been referred for evaluation of enlarged lymph nodes. Preauricular/submandibular and inguinal lymph nodes (n = 2 each) were involved. Three patients had skin traumas and visited the same natural spring. The diagnosis was delayed because a history of aquatic exposure was initially missed. Two children were managed with anti-mycobacterial antibiotics and 2 by observation only. All showed good resolution. CONCLUSION: A detailed history, specifically regarding exposure to spring water sources, in cases of lymphocutaneous syndrome can point to the diagnosis of M. marinum infection. What is Known: • M. marinum can cause chronic nodular or ulcerative skin infections. • Lymphadenitis due to M. marinum has rarely been reported. What is New: • M. marinum infection can present as isolated chronic lymphadenitis; it accounts for about 2.4% of all cases of nontuberculous mycobacterial lymphadenitis and it tends to occur in noncervicofacial regions relative to infections of other nontuberculous mycobacterial species. • Careful history taking including water source exposure, especially in association with skin trauma, can point to the correct diagnosis in children with chronic lymphadenitis.