Diagnosis of Kaposi sarcoma by a modified fine needle aspiration method combing cell block in Chinese patients with human immunodeficiency virus/acquired immunodeficiency syndrome

All cell blocks were treated similarly to surgical biopsy specimens, including formalin fixation, paraffin embedding, and sectioning at 4 to 5 μm thickness, followed by H&E staining and immunohistochemical staining. The study protocol was approved by the Ethics Committee of Beijing Ditan Hospital, Capital Medical University (No. 2019-049). The tumor contained proliferating blood vessels arranged in slit-like spaces and fascicles that were full of red blood cells. According to the results of immunohistochemical stains, the tumor cells were highly positive for CD31, CD34, factor VIII, Vimentin, and HHV-8 [Figure 1C, and 1D].