Pulmonary involvement in Kaposi sarcoma: correlation between imaging and pathology

Abstract

Kaposi sarcoma is a low-grade mesenchymal tumor involving blood and lymphatic vessels. There are four variants of this disease, each presenting a different clinical manifestation: classic or sporadic, African or endemic, organ transplant-related or iatrogenic, and AIDS-related or epidemic. Kaposi sarcoma is the most common tumor among patients with HIV infection, occurring predominantly in homosexual or bisexual men. The pulmonary involvement in Kaposi sarcoma occurs commonly in critically immunosupressed patients who commonly have had preceding mucocutaneous or digestive involvement.The etiology of Kaposi sarcoma is not precisely established; genetic, hormonal, and immune factors, as well as infectious agents, have all been implicated. There is evidence from epidemiologic, serologic, and molecular studies that Kaposi sarcoma is associated with human herpes virus type 8 infection. The disease starts as a reactive polyclonal angioproliferative response towards this virus, in which polyclonal cells change to form oligoclonal cell populations that expand and undergo malignant transformation.The diagnosis of pulmonary involvement in Kaposi sarcoma usually can be made by a combination of clinical, radiographic, and laboratory findings, together with the results of bronchoscopy and transbronchial biopsy. Chest high-resolution computed tomography scans commonly reveal peribronchovascular and interlobular septal thickening, bilateral and symmetric ill-defined nodules in a peribronchovascular distribution, fissural nodularity, mediastinal adenopathies, and pleural effusions. Correlation between the high-resolution computed tomography findings and the pathology revealed by histopathological analysis demonstrate that the areas of central peribronchovascular infiltration represent tumor growth involving the bronchovascular bundles, with nodules corresponding to proliferations of neoplastic cells into the pulmonary parenchyma. The interlobular septal thickening may represent edema or tumor infiltration, and areas of ground-glass attenuation correspond to edema and the filling of air spaces with blood. These findings are a result of the propensity of Kaposi sarcoma to grow in the peribronchial and perivascular axial interstitial spaces, often as continuous sheets of tumor tissue.In conclusion, radiological findings can play a major role in the diagnosis of pulmonary Kaposi sarcoma since characteristic patterns may be observed. The presence of these patterns in patients with AIDS is highly suggestive of Kaposi sarcoma.

Human Immunodeficiency Virus–Associated Lung Malignancies

“…In the HAART era, the current CD4 count is the patient characteristic that is most predictive of risk for KS 29 . Imaging findings of peribronchovascular nodularity and thickening, interlobular septal thickening and fissural nodularity consistent with KS often parallel bronchoscopic findings; however, patients can present with parenchymal findings noted on computed tomography (CT) without evidence of endobronchial lesions 30–31 . Diagnosis can be made via bronchoscopic visualization of typical KS-appearing endobronchial lesions, if present.…”

A Review of Human Herpesvirus 8, the Kaposi's Sarcoma-Associated Herpesvirus, in the Pediatric Population

“…Pulmonary involvement may not be visible or may be difficult to distinguish from other disease processes on chest radiographs. Lesions in the bronchial tree below the carina are suggestive of pulmonary involvement in a patient suspected to have KS [70]. Chest radiograph may demonstrate reticular opacities and parenchymal nodules with a bronchovascular distribution and can reveal hilar or mediastinal adenopathy, pleural effusion, or consolidation [70].…”

Pulmonary manifestations of human herpesvirus-8 during HIV infection

“…3). Small or moderate, unilateral or bilateral pleural effusion is frequent [40,42]. Alternatively, chest radiography may give normal results or may show superimposed abnormalities of Kaposi sarcoma and an opportunistic infection.…”

“…Typical peribronchovascular fusing from the pulmonary hilum, septal thickening, consolidations, mediastinal lymphadenopathy, or a small or moderate pleural effusion may be present ( fig. 4) [39,40,42,43].…”

“…in a patient with cutaneous Kaposi sarcoma, peribronchovascular and septal thickening, CD4 count ,200 cells?mm -3 and exclusion of opportunistic infection by BALF analysis [42]). …”