Histological Subgroups in Classic Kaposi Sarcoma: A Preliminary Study

Background and Design: Kaposi sarcomas (KS) are vascular tumors with a low malignant potential which include overlapping infectious, immunologic, and neoplastic processes. Recently, many histological subtypes have been defined. Material and Method: In the present study, 151 cutaneous classic KS lesions in 56 patients were retrospectively evaluated with regard to histological subtypes. Determination of the subtypes was based on the predominant histopathological component in the lesion. We examined changes in epidermis and dermis along with intratumoral inflammatory response characteristics in the lesions. By defining histopathological variants of the cases, differences regarding subtypes were investigated. Results: Cases that bear the ordinary characteristics of KS and those that can not be classified otherwise, comprised 82..8% of the study group. Twenty-six cases showed consistency with the subtypes outlined in the literature in terms of their histopathological properties. The most common histological subtype was the lymphangiectatic variant in 7.3% of the cases. Bullous (2.6%), lymphangioma like (2.6%), intravascular (2%), and pyogenic granuloma like (2%) variants were less common. The most uncommon histological subtype was micronodular (0.6%) type. Lymphangiectatic, bullous, intravascular, and pyogenic granuloma like variants were frequently observed in the nodular stage of KSs. Lympangioma like changes were seen to be present in the early KS lesions. Lymphangiectatic type was oftenly associated with bullous component, whereas pyogenic granuloma like type demonstrated superficial ulceration and intense inflammatory response. Lymphangioma like and intravascular types exhibited a characteristic appearance, while other variants were accompanied by components belonging to different subtypes. Conclusion: In KS, histopathological subtypes can develop as a result of different pathological processes. The next stage of the current study, which is one of the largest case series in the literature, will be investigation of the clinical and prognostic characteristics of the variants. (Turkderm 2010; 44: 73-8)