Cutaneous Leishmaniasis or Fish tank granuloma?:Which one is the Correct Diagnosis? A Case series Study on Fish tank Granuloma with Primary Diagnosis of Cutaneous Leishmaniasis in Mashhad, IRAN

Mycobacterium marinum is a free living acid fast bacterium which classified as atypical mycobacterium and causes a 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.
During 3 months (2016), three people who had cutaneous lymphatic lesions on their extremities were referred to parasitology laboratory of Emam Reza Hospital and special clinics. All of the individuals were clinically examined by dermatologists and introduced to the laboratory with primary diagnosis of cutaneous Leishmaniasis. Of these 2 individuals were male and 1 was female. All of the patients had history of direct contact with fish. Direct Giemsa stained smear and consequently, Ziehl- Neelsen stained smear and culture on Lowenstein- Jensen medium was performed for each individual. The results showed that all of Giemsa stained smears were negative for Leishmania spp., but the result of Ziehl-Neelsen stained smears were positive for Mycobacterium spp. The egg yolk like colonies grown on culture, confirmed Mycobacterium marinum infection.
Fish tank granulomais an emerging sporadic skin disease in Mashhad. 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.