**Question:** Child with kidney transplant developed lympho-proliferative cancer. This is due to which viral infection -

A. Human Herpesvirus-6 (HHV-6)
B. Human Herpesvirus-4 (HHV-4 - Epstein-Barr virus)
C. Human Papillomavirus (HPV)
D. Human Immunodeficiency Virus (HIV)

**Correct Answer:** B. Human Herpesvirus-4 (HHV-4 - Epstein-Barr virus)

**Core Concept:**
The question pertains to the association between viral infections and the development of lympho-proliferative cancers in immunocompromised patients, such as those with kidney transplants. In this case, the correct answer is Human Herpesvirus-4 (HHV-4), also known as Epstein-Barr virus (EBV).

**Why the Correct Answer is Right:**
Epstein-Barr virus (EBV) is a common human herpesvirus that is known to cause lymphoproliferative disorders in immunocompromised individuals, particularly those with organ transplants or HIV infection. The virus establishes latency within B cells, leading to the production of B cell lymphomas and other lymphoproliferative disorders.

**Why Each Wrong Option is Incorrect:**
A. Human Herpesvirus-6 (HHV-6) is another member of the herpesvirus family, but it is primarily associated with neurological disorders, encephalitis, and early infections in children, rather than lymphoproliferative cancers.
B. Human Papillomavirus (HPV) is known to cause genital warts and various skin lesions, but it is not directly linked to lymphoproliferative disorders in immunocompromised patients.
C. HIV infection is primarily associated with Kaposi's sarcoma, pneumonitis, and other opportunistic infections, not lymphoproliferative cancers.

**Clinical Pearl:**
In the context of immunocompromised patients, it is crucial to understand the various viral infections and their clinical associations. Knowledge of these relationships helps guide diagnostic strategies and treatment options for patients with lymphoproliferative disorders.