Answer of Dermatopathology Case 49

Ziehl-Neelsen staining revealed acid-fast bacilli

Mycobacterium Marinum Infection (Fish Tank Granuloma ; Swimming Pool Granuloma)

Abstract:

Fish-Tank GranulomaN Engl J Med 1997; 336:1065April 10, 1997

Fish tank granuloma.BMJ. 1990 April 21; 300(6731): 1069–1070.

Fish tank granuloma: misdiagnosed as cutaneous leishmaniasis. Int J Dermatol. 2010 Jan;49(1):53-5.

Mycobacterium marinum is an atypical mycobacterium that causes a skin infection known as fish tank granuloma or swimming pool granuloma affecting people who are exposed to aquatic environments. In general, it is managed medically with antimicrobials and variable treatment protocols. Here, we report a Saudi gentleman who acquired this infection in Thailand and was misdiagnosed as cutaneous leishmaniasis. After establishing the correct diagnosis, treatment with minocycline and trimethoprim-sulfamethoxazole resulted in rapid healing.

Mycobacterium marinum infections in transplant recipients: case report and review of the literature.Transpl Infect Dis.2008 Oct;10(5):358-63.

Infections due to Mycobacterium marinum are rarely encountered following organ and tissue transplantation. Herein, we report a case of M. marinum infection in a kidney and pancreas transplant recipient who manifested clinically with multiple locally spreading sporotrichoid-like cutaneous nodules in his left forearm. In order to provide a general overview of post-transplant M. marinum infections, we reviewed and summarized all previously reported cases of this infection that occurred after transplantation. Including our index case, all 6 cases presented with multiple cutaneous and subcutaneous nodules that had spread locally in the involved extremity. One patient had lesions located in non-contiguous body sites suggesting either systemic dissemination or multiple sites of inoculation. In all but 1 patient, the cutaneous nodules appeared in an ascending pattern and following exposure to fish tanks or after contact with the marine environment. The diagnosis of M. marinum infection was suspected on clinical grounds and confirmed by mycobacterial culture. Treatment consisted of at least 2 active antibiotics (such as rifamycins, ethambutol, tetracyclines, or macrolides) for 4-9 months, resulting in clinical cure or improvement. Relapse was observed in 1 patient despite completing 6 months of antibiotic therapy. One patient had surgical excision of the lesions. In conclusion, M. marinum should be considered as the cause of cutaneous and subcutaneous nodules in transplant recipients, particularly in the context of fish tank or marine exposure. Compared with the immunocompetent hosts, M. marinum infection may have a more aggressive clinical course after transplantation, and may require a longer duration of antibiotic treatment. Early diagnosis and treatment may prevent local spread and potential systemic dissemination.

Disseminated Mycobacterium marinum infection with extensive cutaneous eruption and bacteremia in an immunocompromised patient.Eur J Dermatol.2006 Jan-Feb;16(1):79-83.

Mycobacterium marinum can cause fish tank granuloma (or swimming pool or aquarium granuloma) in immunocompetent patients. Dissemination of Mycobacterium marinum-infection is a rare condition which occurs mainly in immunocompromised patients and can be life-threatening. We report the case of an 87-year-old woman who was treated with oral corticosteroids for polymyalgia rheumatica for many years and developed erythema nodosum-like lesions on the right forearm and arthritis of the right wrist. By increasing the steroid dosage and adding methotrexate only short-term remission was achieved. Seven months later painful erythematous nodules occurred on all extremities which became necrotic, ulcerative and suppurative. Ziehl-Neelsen staining revealed acid-fast bacilli and Mycobacterium marinum was cultured from skin biopsies, blood, and urine. The critically ill patient was treated with clarithromycin and ethambutol resulting in a dramatic improvement of the general condition. After four months, doxycycline had to be added because of new skin lesions. This case illustrates the impact of Mycobacterium marinum infection in immunocompromised patients.

Fish tank granuloma--a frequently misdiagnosed infection of the upper limb. J Accid Emerg Med.1997 Nov;14(6):398-400.

Five patients attended the accident and emergency (A&E) department with fish tank granuloma caused by an infection with Mycobacterium marinum. All patients had forearm symptoms which were initially misdiagnosed. They were later recognised by the presence of superficial cutaneous lesions in a sporotrichotic distribution. Definitive diagnosis was confirmed by the histological appearances of a biopsy and or culture of the organism. All patients responded to oral minocycline and had uncomplicated recoveries once the diagnosis was established. A&E doctors need to be aware of the possible diagnosis of fish tank granuloma especially when treating forearm infections which have been resistant to antibiotics.