Oncogenic viruses – association check: Which virus has a well-established causal association with Kaposi's sarcoma in humans?

Introduction:
Several human cancers are linked to specific viruses. Recognizing the correct pairing between tumor entity and etiologic virus is essential in pathology and epidemiology. Kaposi's sarcoma has a signature viral driver that should be memorized.

Given Data / Assumptions:

• The neoplasm is Kaposi's sarcoma.
• Options list common oncogenic viruses.
• We seek the strongest, well-accepted causal link.

Concept / Approach:
Human herpesvirus 8 (also called Kaposi's sarcoma–associated herpesvirus, KSHV) is detected in virtually all forms of Kaposi's sarcoma (classic, endemic, iatrogenic, and AIDS-related). Viral genes promote angioproliferation and immune evasion, and seroepidemiology tracks disease prevalence.

Step-by-Step Solution:
Recall signature tumor–virus pairs taught in oncology. Match Kaposi's sarcoma with HHV-8/KSHV. Confirm no other listed virus is the principal causal agent. Select HHV-8.

Verification / Alternative check:
Immunohistochemistry for LANA-1 (latency-associated nuclear antigen) of HHV-8 is routinely positive in tumor cells, serving as a diagnostic test.

Why Other Options Are Wrong:
Epstein–Barr virus – associated with Burkitt lymphoma, nasopharyngeal carcinoma, some Hodgkin lymphomas.

Human T-cell lymphotropic virus – linked to adult T-cell leukemia/lymphoma.

Human papillomavirus – linked to cervical and anogenital cancers and subsets of head and neck cancers.

Merkel cell polyomavirus – associated with Merkel cell carcinoma.

Common Pitfalls:
Confusing HHV-8 with EBV because both are herpesviruses; their tumor spectra differ.

Final Answer:
Human herpesvirus 8 (HHV-8).