Clinical, histological and immunohistochemical findings in oral Kaposi's sarcoma in a series of Mexican AIDS patients. Comparative study

Background: The origin of spindle cells (SC) in oral Kaposi’s sarcoma (OKS) is still an intriguing aspect. Thus the aim of the present study was to compare the clinical, histological and immunohistochemical characteristics of OKS and oral pyogenic granuloma (OPG), in order to contribute to the knowledge of the cells involved in Kaposi′s sarcoma pathogenesis. Methods: In this retrospective, observational and comparative study, 39 OKS and 30 OPG cases were included. Immunohistochemical studies were performed for vimentin, αSMA, desmin, C‐kit, CD34, D2‐40 and LANA‐1 [human herpesvirus‐8(HHV‐8)]. Statistical comparisons were done using the chi‐square and Wilcoxon–Mann–Whitney rank sum tests. Results: Fourteen (35.9%) OKS cases also affected the skin, and 83.8% involved the palate. All OKS and OPG were positive for vimentin and CD34. OKS samples were positive for αSMA, and 25.6% expressed C‐kit. All OKS cases were positive for HHV‐8, and the number of positive cells increased significantly from early / intermediate to late histological stage. D2‐40 was expressed in the cellular component and vascular walls of all OKS cases, but it was negative in OPG. HHV‐8 expression was increased in late histological stages of OKS lesions. Conclusions: The expression of D2‐40 marker in the vascular walls and SC supports the view of a lymphatic differentiation in neoplastic cells of OKS. Desmin, αSMA, D2‐40, C‐kit and HHV‐8 were the main markers differently expressed in OKS and OPG.