A Case of Hypercalcemia in an Immunocompetent Patient with Disseminated Mycobacterium marinum Infection with a Rain Barrel as the Most Likely Primary Source

Infection with Mycobacterium marinum is common in fish, and so human infection usually arises from contact with contaminated water or fish. A solitary papulonodular lesion on a finger or hand is the typical presentation. Disseminated infections are rare and mostly seen in immunocompromised patients. We present a rare case of disseminated M. marinum infection presenting with polyarthritis, tenosynovitis, dactylitis, and (sub)cutaneous and intramuscular lesions in an immunocompetent patient. This case was complicated by hypercalcemia, renal failure and eventually death. A contaminated rain barrel was most likely the primary source of the infection. LEARNING POINTS: Given the similarities, it is key to differentiate Crohn’s disease from intestinal tuberculosis as early as possible. Patients undergoing colonoscopy for possible Crohn’s disease should have colonic biopsy samples sent for AFB culture. Consider investigations for intestinal tuberculosis in uncontrolled Crohn’s disease where intestinal tuberculosis has not been worked up previously.