How do I diagnose Microscopic challenge: Kaposi Sarcoma of the oral mucosa

Kaposi Sarcoma is a rare vascular neoplasm of the skin and mucosal membranes associated with human herpes virus 8 (HHV-8) infection. It is usually associated with severe suppression of the immune system, e. g. in the setting of human immune deficiency virus (HIV) infection and aquired immune deficiency syndrome (AIDS). Here we present a case of a 33 year old female, who was diagnosed to be HIV-positive in march 2015. On physical examination petechial bleedings were recognized at the hard palate. The biopsy specimen showed an ulcerated squamous mucosa with granulation tissue. Single swollen endothelia within angulated vessels were suspicious for a vascular tumor. Immunohistochemical evaluation revealed proliferating endothelia positive for HHV-8. Thus, the diagnosis of a Kaposi Sarcoma within granulation tissue at the hard palate was made. The diagnosis of Kaposi Sarcoma can be very difficult, especially in the setting of concurrent inflammation. Immunohistochemical workup is therefore recommended and necessary to verify the diagnosis of Kaposi Sarcoma.