Fish Tank Granuloma Presenting as a Nasal Cavity Mass

Mycobacterium marinum is a free-living nontuberculous mycobacterium that is widely distributed in freshwater and seawater around the world. Granulomatous skin infection from M. marinum in people who are exposed to fish or aquatic environments is a rare condition known as fish tank granuloma. The granuloma mainly occurs on the skin of the upper limb, in a few cases on the face, and rarely in the nasal cavity. We describe a case of M. marinum infection that presented as a nasal cavity mass. A 57-year-old woman who was receiving infliximab for psoriatic arthritis visited our hospital with a complaint of right nasal obstruction. A granulomatous mass with an irregular surface was found in the anterior part of the right nasal cavity. Tissue biopsy revealed granulation tissue. Since the application of steroid ointment did not reduce the size of the mass, the tumor was resected under local anesthesia, and the base was cauterized. The pathological finding was an inflammatory granuloma with negative Ziehl–Neelsen staining. The granuloma recurred 3 months after resection. The interferon-gamma release assay (IGRA) test was positive, and therefore, a mycobacterial tissue culture test was performed because of suspected nasal tuberculosis, which identified M. marinum. The nasal cavity mass disappeared 2 months after the administration of minocycline, followed by clarithromycin, and subsequent discontinuation of infliximab. M. marinum infection can cause an intranasal mass. IGRA and the mycobacterial tissue culture test are useful for diagnosis. As in this case, the nasal lesion may be excised as an inflammatory nasal granuloma, and therefore, there may be many more “hidden” cases of M. marinum infection. If nasal granulation is present, the possibility of M. marinum infection should be considered.

Difficulties in the diagnosis of fish tank granuloma – case report

Introduction: Fish tank granuloma is a rare dermatitis caused by Mycobacterium marinum. Infection occurs through contact of damaged skin with water or aquatic animals infected with these bacteria. Aim: It is likely that skin infection caused by M. marinum transmitted from Clarias gariepinus has as yet not been reported in literature. Our case report is presumably the first publication. Dermatoscopy as a useful method in the diagnosis of skin infections caused by atypical mycobacteria. Our article presents new dermatoscopic features of fish tank granuloma. Case study: The case report applies to a 30-year old, white, Caucasian man referred because of a single, well-demarcated plaque measuring 2 × 4 cm, localized on third finger on left hand above proximal phalanx, without subjective symptoms. The diagnosis was confirmed by medical history, dermoscopy and histopathological examination. Patient was successfully treated with sulfamethoxazole and trimethoprim. Results and discussion: Due to the fact that M. marinum infection is uncommon, in case of clinical suspicion it is necessary to perform skin biopsy, culture and tissue PCR analysis. Knowledge about the opportunities and limitations of theses laboratory tests is pivotal to reasonable clinical decision-making. Conclusions: Dermoscopy is useful to make a diagnosis, but there are still too few accounts in literature. The correct diagnosis determines the effective treatment.

Clinical, Dermatoscopical and Laboratory Essentials of Fish Tank Granuloma

In immunocompetent individuals Mycobacterium marinum (M. marinum) infection usually presents with localized skin lesions, better known as “swimming pool granuloma” or “fish tank granuloma” (FTG). When establishing the diagnosis of FTG, doctors encounter several problems in the clinical practice: granulomas are detected in less than two thirds of biopsies and acid-fast bacilli are identified only in a minority of cases. Majority of disseminated and aggressive FTG forms are unrecognized at the beginning, and occur in immunosuppressed patients, including organ transplant patients. Functional impairment or even amputation of the extremity, visceral involvement and lethal outcome have been reported. Although more than one thousand cases of FTG have been reported worldwide, dermatoscopy of FTG, as a diagnostic aid, has not been reported yet. Presenting the case of FTG of recent onset where, guided by dermatoscopy, microorganisms were isolated and identified from the biopsy material, we summarize the essentials of clinical and laboratory diagnostics of M. marinum infection.