Diagnosis: Disseminated Mycobacterium marinum
SAN DIEGO The differential diagnosis in this immunocompromised patient pointed to infection, likely complicated by an underlying process related to Crohn's disease and/or pyoderma gangrenosum.
Bacterial infection, Mycobacterium tuberculosis, atypical mycobacterium, Treponema pallidum, deep fungal infection, and viral infection were considered, as were potential contributors such as pyoderma gangrenosum, metastatic Crohn's disease, cutaneous lymphoma, and/or vasculitis.
A blood culture was negative. Skin biopsies revealed ulceration, fibrinous inflammation, necrosis, and mixed cell infiltrate. A Fite stain was positive for acid-fast bacteria. Biochemical analysis of tissue cultures revealed Mycobacterium marinum, "of fish tank granuloma fame," said Dr. Jeffrey Vallee at the annual meeting of the California Society of Dermatology and Dermatologic Surgery.
The patient was asked whether she had an aquarium. She replied, "Well, I don't have any fish, but they call me the Chameleon Lady," Dr. Vallee recalled.
The patient's pets included African water frogs, tortoises, newts, geckos, and chameleons, "one of which she had eaten with, slept with, and showered with for the last few weeks of his life," said Dr. Vallee, a dermatology resident at the University of California, Irvine, who worked on the case with Dr. Tanya Kormeili, Dr. Kenneth G. Linden, and Dr. Ronald J. Barr.
The incidence of M. marinum is 0.27 per 100,000, with about 85% of cases associated with contact with aquariums. Disseminated M. marinum is rare, with fewer than 10 reported cases in the literature, and this case is believed to be the first involving infliximab.
The patient spent 7 weeks in the burn unit, undergoing daily hydrotherapy and repeated surgeries for debridement and application of split-thickness skin grafts.
She was treated with a triad of antibiotics: clarithromycin, doxycycline, and ethambutol. By discharge, her prednisone dose had been tapered to 7.5 mg.
"The antibiotics essentially cleared her and she's had no skin lesions since," Dr. Vallee reported.
A Fite stain was positive for acid-fast bacteria, and biochemical analysis of tissue cultures revealed Mycobacterium marinum. Courtesy Dr. Jeffrey Vallee