Hepatic granulomas associated with brucellosis

摘要

Brucellosis, a bacterial disease caused by members of the ge-nus Brucella, remains one of the most common zoonotic dis-eases worldwide (1-3). The disease occurs in both animals and humans, except in those countries where bovine Brucellosis has been eradicated (1). The bacterial pathogen is classified by the CDC as a category-B pathogen that has potential for develop-ment as a bioterrorist agent (1, 4). Brucella spp. is considered to be the most common laboratory-acquired pathogen (1, 5). In hu-mans, Brucellosis behaves as a systemic infection with a very het-erogeneous clinical spectrum (2, 3, 6). The Brucella organism's predilection for organs rich in reticuloendothelial cells (spleen, liver, bone marrow, lymph nodes) and its intracellular location are responsible for the chronicity of the disease, which can last for months or even years (1, 2, 7). Brucella has been reported to compromise the central and peripheral nervous system, as well as the gastrointestinal, hepatobiliary, genitourinary, musculo-skeletal, cardiovascular, and integumentary systems (2). In pa-tients with Brucellosis, the gastrointestinal system is commonly compromised (70%) (5). Because the liver is the largest organ of the reticuloendothelial system and plays the important role of defense mechanism against Brucella infections, diffuse hepatic involvement is usually recorded during the course of human Brucellosis infection (8). Brucellosis involves the liver in varying ways, including a slight increase in transaminase levels, mild hepatosplenomegaly, chronic suppurative disease, and, more rarely, acute hepatitis (5, 8-13). In patients infected with Brucella melitensis, the involvement of bile canals is observed more of-ten than other Brucellosis factors (14). Hepatic granulomas are often encountered during liver biopsy and can be caused by a variety of conditions such as a primary hepatic process, fever of unknown origin, or a manifestation of a systemic illness (15, 16). Granulomas are reportedly present in 2 to 10% of all liver-biopsy specimens examined in general practice (17). Liver Brucelloma, or pseudotumoral necrotizing granuloma, is an uncommon type of hepatic manifestation by Brucella and is observed in only 1.7% of patients affected by Brucellosis (8). Hepatic Brucel-loma is rarely the first to manifest itself clinically, and a focal suppurative lesion may occur if acute Brucellosis is undetected or undertreated in the patient (18). Granulomas are aggregates of macrophages, often admixed with other inflammatory cells, which usually result from a chronic presence of antigens. Gran-ulomas are a unique inflammatory response that may be idio-pathic or may be a response to a bacterial, fungal, viral, or para-sitic infection, in the latter cases representing a manifestation of underlying malignancy (15, 17).The pathology report on Bru-celloma usually shows necrotizing granulomas with a periph-eral halo of epithelioid cells. lymphocytes, and plasma cells, as well as and a polimorphonuclear infiltrate in the necrotic area (19-21). Brucellosis involving Brucella abortus is the most com-mon species that can cause hepatic granulomas that are indis-tinguishable from sarcoidosis (13, 16), and Brucella abortus is the most common species that can cause hepatic granulomas.