Clinical Implications for the Timely Diagnosis of Mycobacterium marinum in the Age of Biologic Therapy: A Case Report and Review of the Literature

Abstract

Mycobacterium marinum infections typically present as cutaneous nodular lesions with a sporotrichoid lymphatic spread on extensor surfaces of extremities. The natural history of this infection can be altered if the host is immunosuppressed, leading to disseminated presentations. A detailed exposure history and high degree of suspicion for this indolent pathogen are often required for the correct diagnosis of this disease. We present a case of a 67-year-old male misdiagnosed with seronegative rheumatoid arthritis presenting with rheumatic nodules. Initiation of chronic immunosuppressant therapy including biologic monoclonal antibodies resulted in the exacerbation of initially localized disease to broadly disseminated lymphatic, joint, and myotendinous granulomatous disease and led to delay in the correct diagnosis. Cessation of immunosuppressants, with a prolonged course of antimicrobial therapy and multiple surgical debridements were required for cure.

Figure 1

Summary timeline of patient clinical course and treatments.

Figure 2

Sporotrichoid spreading of M. marinum via lymphatic and myotendinous spreading in disseminated disease. (a) Unilateral granulomatous disease with soft tissue swelling due to lymphatic obstruction, (b) radiograph demonstrating unilateral left soft tissue swelling in absence of erosive disease, (c) dorsal aspect of distal left forearm with visible nodules, and (d) MRI demonstrating myotendinous necrotic granuloma (white circle) in distal aspect of extensor carpi ulnaris.

Figure 3

Pre- and postantibiotic therapy photos of lymphatic granulomatous disease from disseminated M. marinum infection. (a) preantimicrobial therapy and (b) posttherapy cure (left-to-right: palmar inflamed granulomas 4th/5th digits and resolution, dorsal lymphogranulomatous spread with soft tissue swelling of the left hand and corresponding resolution photo, surgical excision of left elbow granulomatous bursitis, and resolved inflammation with remnant scarring).