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.