A Rare Cause of Granulomatous Hepatitis Presenting as Fever of Unknown Origin

Abstract

Case: A 73 year old female with a past medical history of diabetes, presented with fatigue and fever. These symptoms began two months prior to admission and were noted after a femoral popliteal bypass two weeks prior to admission. Elevated liver enzymes evaluated by abdominal ultrasound revealed echogenic foci in the liver. These foci were consistent with hepatic abscesses, with ring enhancement and surrounding hyperemia on CT and MRI imaging. Liver biopsy performed on three separate occasions revealed necrotizing granulomatous inflammation, with histological features highly suggestive of an infectious etiology. AFB smear was negative, but tissue culture grew Mycobacterium abscessus one month later. After discharge, she again developed fever with enlarging abscesses on CT scan. She is currently doing well on imipenem, ceftriaxone, and amikacin. Investigation: Our patient underwent extensive investigations that led to the diagnosis by culture of the liver biopsy. Initial workup for a fever of unknown origin, revealed WBC of 12.7, AST of 69, ALT of 56, alkaline phosphatase of 343, albumin of 3.7, an INR of 2.4. Blood cultures were negative on numerous occasions. Chest x-ray was clear. Tests for cryptosporidium, E. histolytica, B. burgdorferi, malaria, coccidiomycosis, histoplasmosis, brucella, tularemia, rocky mountain spotted fever and syphilis were all negative. Viral studies ruled out the hepatitides, CMV, EBV and HIV. The necrotizing granulomas found on core needle liver biopsy ruled out sarcoid and drug induced granuloma. Autoimmune etiologies such as Wegeners granulomatosis, PBC, PSC, and autoimmune liver disease were also ruled out. Discussion: Hepatic granuloma is a immune reaction brought on by many etiologies. Often the causative agent remains unknown. In the United States, sarcoidosis and tuberculosis are the most common etiological factors causing hepatic granuloma. Liver biopsy from our patient grew Mycobacterium abscessus. This infectious agent has been documented in cases of soft tissue infections in post-surgical and traumatic skin wounds. It has also been isolated in patients with cystic fibrosis. After careful review of the literature, M. abscessus has never been reported to be responsible in the formation of liver granulomata in humans. This case emphasizes consideration of other more obscure and rare etiologies such as a M. abscessus infection as a possible cause for granulomatous hepatitis and hepatic microabscess formation.