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Infectious Disease and Microbiology – Bacillary Angiomatosis / Peliosis Hepatica
Bacillary angiomatosis (BA) and peliosis hepatica (PH) are rare vascular proliferative infections caused by Bartonella species, most commonly affecting immunocompromised individuals, particularly those with advanced HIV infection and T-cell deficiency. Bacillary angiomatosis typically refers to the cutaneous or disseminated vascular form, whereas peliosis hepatica describes the visceral form involving blood-filled cystic lesions in the liver. If left untreated, the disease can be fatal.
This condition is globally distributed but uncommon. It is most frequently reported in individuals with HIV infection, particularly those with CD4 counts below 100 cells/mm³. Other risk factors include immunosuppression from transplantation or malignancy, poor sanitary conditions, homelessness, and close contact with cats. Bartonella henselae is most often associated with bacillary angiomatosis and cat exposure, while Bartonella quintana is linked to body louse infestation and is more commonly associated with bacteremia in homeless populations.
Preventive measures for immunocompromised individuals include careful handling of cats. Patients are advised to obtain healthy cats older than one year, practice strict hand hygiene after cleaning litter boxes, and avoid scratches or bites. Routine declawing or testing of cats is not recommended. Primary prophylaxis is generally not advised, although macrolides may offer protective effects against Bartonella infection. The need for lifelong suppressive therapy in HIV-infected patients has not been clearly established.
After an incubation period of at least one week, clinical manifestations can range from isolated bacteremia to extensive cutaneous, visceral, osseous, or central nervous system involvement. Constitutional symptoms such as fever, malaise, weight loss, and anemia are common. Peliosis hepatica often presents with persistent fever, abdominal pain, nausea, vomiting, and progressive hepatomegaly.
Cutaneous manifestations occur in the majority of patients with bacillary angiomatosis. Lesions are typically bright red, elevated papules that may vary from a few millimeters to several centimeters in size and may number from one to hundreds. Smaller lesions may have a thin overlying epidermis, while larger lesions may ulcerate or bleed easily and are often surrounded by a collarette. Subcutaneous nodules may develop without visible skin changes. Cellulitic plaque-like lesions may overlie deeper bone involvement. Extracutaneous manifestations include bone lesions, visceral involvement of the liver and spleen, lymphadenopathy, and, rarely, brain abscesses. Bone disease may present with pain alone or in association with overlying skin lesions. Peliosis hepatica is characterized by massive hepatomegaly and sometimes splenomegaly.
Diagnosis relies on tissue biopsy. Histologic examination using hematoxylin and eosin staining may show granular purple material representing organisms, while Warthin–Starry or Brown–Hopps staining can better visualize the bacteria. The organisms appear singly or in clusters. Culture is difficult and requires prolonged incubation (at least 21 days) using lysis-centrifugation techniques. Polymerase chain reaction (PCR) testing can aid in species identification. Serologic testing has limited sensitivity in immunocompromised patients. Laboratory findings may include mild elevation of transaminases, marked elevation of alkaline phosphatase, and mild-to-moderate pancytopenia in visceral disease.
Imaging findings depend on organ involvement. Bone radiographs may reveal well-circumscribed lytic lesions or cortical destruction with aggressive periosteal reaction. CT scans may demonstrate hepatosplenomegaly and abdominal lymphadenopathy, with heterogeneous liver parenchyma. Liver biopsy in peliosis hepatica shows dilated, blood-filled cystic spaces within the hepatic parenchyma, often with associated necrosis in advanced cases.
The differential diagnosis includes Kaposi’s sarcoma, pyogenic granulomas, angiomas, and other vascular tumors. Kaposi’s sarcoma may coexist with bacillary angiomatosis and should be considered, particularly if lesions fail to improve with antibiotic therapy.
Treatment begins with evaluation of the extent of organ involvement. First-line therapy consists of erythromycin 500 mg orally every six hours or doxycycline 100 mg orally twice daily. Treatment duration is generally three months for bacillary angiomatosis and four months for peliosis hepatica, with longer courses required in immunocompromised patients. A Jarisch–Herxheimer reaction may occur after initiation of therapy; pretreatment with antipyretics for the first 72 hours may help.
For patients intolerant to first-line therapy, azithromycin or clarithromycin may be used. In severe, life-threatening, or central nervous system disease—particularly in immunocompromised individuals—combination therapy with rifampin added to erythromycin or doxycycline is recommended. TMP-SMX and ciprofloxacin have shown inconsistent results. Most patients can be managed as outpatients, though hospitalization and intravenous therapy are necessary for extensive or fulminant disease.
Clinical improvement is often observed within 4–7 days of therapy, with near-complete resolution of lesions by 3–4 weeks. Relapses occur in approximately 15% of cases and may require prolonged suppressive therapy. Monitoring includes clinical assessment, serial liver function tests in visceral disease, and imaging studies for bone involvement.
Complications of visceral disease include anemia, pancytopenia due to hypersplenism, and splenic rupture with hemoperitoneum. Early recognition and prolonged antimicrobial therapy are essential for favorable outcomes.
Bacillary angiomatosis (BA) and peliosis hepatica (PH) are rare vascular proliferative infections caused by Bartonella species, most commonly affecting immunocompromised individuals, particularly those with advanced HIV infection and T-cell deficiency. Bacillary angiomatosis typically refers to the cutaneous or disseminated vascular form, whereas peliosis hepatica describes the visceral form involving blood-filled cystic lesions in the liver. If left untreated, the disease can be fatal.
This condition is globally distributed but uncommon. It is most frequently reported in individuals with HIV infection, particularly those with CD4 counts below 100 cells/mm³. Other risk factors include immunosuppression from transplantation or malignancy, poor sanitary conditions, homelessness, and close contact with cats. Bartonella henselae is most often associated with bacillary angiomatosis and cat exposure, while Bartonella quintana is linked to body louse infestation and is more commonly associated with bacteremia in homeless populations.
Preventive measures for immunocompromised individuals include careful handling of cats. Patients are advised to obtain healthy cats older than one year, practice strict hand hygiene after cleaning litter boxes, and avoid scratches or bites. Routine declawing or testing of cats is not recommended. Primary prophylaxis is generally not advised, although macrolides may offer protective effects against Bartonella infection. The need for lifelong suppressive therapy in HIV-infected patients has not been clearly established.
After an incubation period of at least one week, clinical manifestations can range from isolated bacteremia to extensive cutaneous, visceral, osseous, or central nervous system involvement. Constitutional symptoms such as fever, malaise, weight loss, and anemia are common. Peliosis hepatica often presents with persistent fever, abdominal pain, nausea, vomiting, and progressive hepatomegaly.
Cutaneous manifestations occur in the majority of patients with bacillary angiomatosis. Lesions are typically bright red, elevated papules that may vary from a few millimeters to several centimeters in size and may number from one to hundreds. Smaller lesions may have a thin overlying epidermis, while larger lesions may ulcerate or bleed easily and are often surrounded by a collarette. Subcutaneous nodules may develop without visible skin changes. Cellulitic plaque-like lesions may overlie deeper bone involvement. Extracutaneous manifestations include bone lesions, visceral involvement of the liver and spleen, lymphadenopathy, and, rarely, brain abscesses. Bone disease may present with pain alone or in association with overlying skin lesions. Peliosis hepatica is characterized by massive hepatomegaly and sometimes splenomegaly.
Diagnosis relies on tissue biopsy. Histologic examination using hematoxylin and eosin staining may show granular purple material representing organisms, while Warthin–Starry or Brown–Hopps staining can better visualize the bacteria. The organisms appear singly or in clusters. Culture is difficult and requires prolonged incubation (at least 21 days) using lysis-centrifugation techniques. Polymerase chain reaction (PCR) testing can aid in species identification. Serologic testing has limited sensitivity in immunocompromised patients. Laboratory findings may include mild elevation of transaminases, marked elevation of alkaline phosphatase, and mild-to-moderate pancytopenia in visceral disease.
Imaging findings depend on organ involvement. Bone radiographs may reveal well-circumscribed lytic lesions or cortical destruction with aggressive periosteal reaction. CT scans may demonstrate hepatosplenomegaly and abdominal lymphadenopathy, with heterogeneous liver parenchyma. Liver biopsy in peliosis hepatica shows dilated, blood-filled cystic spaces within the hepatic parenchyma, often with associated necrosis in advanced cases.
The differential diagnosis includes Kaposi’s sarcoma, pyogenic granulomas, angiomas, and other vascular tumors. Kaposi’s sarcoma may coexist with bacillary angiomatosis and should be considered, particularly if lesions fail to improve with antibiotic therapy.
Treatment begins with evaluation of the extent of organ involvement. First-line therapy consists of erythromycin 500 mg orally every six hours or doxycycline 100 mg orally twice daily. Treatment duration is generally three months for bacillary angiomatosis and four months for peliosis hepatica, with longer courses required in immunocompromised patients. A Jarisch–Herxheimer reaction may occur after initiation of therapy; pretreatment with antipyretics for the first 72 hours may help.
For patients intolerant to first-line therapy, azithromycin or clarithromycin may be used. In severe, life-threatening, or central nervous system disease—particularly in immunocompromised individuals—combination therapy with rifampin added to erythromycin or doxycycline is recommended. TMP-SMX and ciprofloxacin have shown inconsistent results. Most patients can be managed as outpatients, though hospitalization and intravenous therapy are necessary for extensive or fulminant disease.
Clinical improvement is often observed within 4–7 days of therapy, with near-complete resolution of lesions by 3–4 weeks. Relapses occur in approximately 15% of cases and may require prolonged suppressive therapy. Monitoring includes clinical assessment, serial liver function tests in visceral disease, and imaging studies for bone involvement.
Complications of visceral disease include anemia, pancytopenia due to hypersplenism, and splenic rupture with hemoperitoneum. Early recognition and prolonged antimicrobial therapy are essential for favorable outcomes.
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