The Emerging Histopathologic Diagnostic Challenges of Kaposi Sarcoma in the Acquired Immunodeficiency Syndrome Era

The acquired immunodeficiency syndrome (AIDS) not only catapulted Kaposi Sarcoma (KS) as the commonest AIDS-associated malignancy, but also introduced a wider histomorphological spectrum and an expanded range of diagnostic mimicry and pitfalls. A tissue diagnosis of KS is necessary because of the clinical differential diagnoses, especially in the skin where overlapping features between diseases are visually appreciated. However, the histopathological diagnostic challenges facing the pathologist are not fully recognized. This review highlights the histomorphological challenges that impact the diagnosis of KS in the context of the mimicry of/by traditional KS variants, increased recognition of uncommon variants, emergent histomorphological variants, impact of co-lesional, co-morbid infections and treatment and procedure-related diagnostic challenges.