Fish tank granuloma, a new neglected emerging disease in Mashhad

Introduction and Objectives: Mycobacterium marinum is a free-living acid-fast bacterium which classified as atypical mycobacterium and causesa cutaneous lymphatic disease called Fish tank or swimming pool granuloma. This agent is the inhabitant of swimming pools, home aquaria and animals living inside salt or fresh water. In this case series study seven patients with fish tank granuloma are presented. Materials and Methods: During 3 years (2016-2018), more than 300 people who had cutaneous lymphatic lesions on their extremities were referred to parasitology laboratory of Emamreza hospital and special clinics. All of the individuals have been clinically examined by dermatologists and introduced to the laboratory with primary diagnosis of cutaneous Leishmaniasis. For those patients whose direct Giemsa smears were negative for Leishman body and had history of direct contact with fish or swimming pool, Ziehl-Neelsen stained smear and culture on Lowenstein- Jensen medium was performed. Results: Ziehl-Neelsen stained smears showed Acid fast bacilli: Mycobacterium spp. on 37 smears. The egg yolk like colonies grown on Lowenstein- Jensen media confirmed Mycobacterium marinum infection. Clinical manifestation of all the patients and result of treatment of some of the lesions were followed up. Conclusion: Fish tank granuloma is an emerging sporadic skin disease in Mashhad and probably other regions in Iran. Skin lesions are similar to cutaneous Leishmaniasis especially sporotrichotic form. Patients with skin lesions, who have previous history of contact with aquarium water, manipulating fish or swimming inside fresh water pools, should be considered for fish tank granuloma.

Keywords:

Mycobacterium marinum , Fish tank granuloma , Cutaneous Leishmaniasis , Mashhad