**Question:** Lichen planus might be associated with

A. Hepatitis C virus (HCV) infection
B. Human papillomavirus (HPV) infection
C. Human immunodeficiency virus (HIV) infection
D. Hormonal imbalance

**Correct Answer:** C. Human immunodeficiency virus (HIV) infection

**Core Concept:** Lichen planus (LP) is a chronic inflammatory disease affecting the skin, oral mucosa, nails, and hair follicles. It is characterized by the presence of flat, violaceous, pruritic papules or plaques. The underlying pathogenesis of LP is not fully understood, but it is believed to be an autoimmune disease involving T-cells.

**Why the Correct Answer is Right:** Lichen planus is known to be associated with certain conditions that affect the immune system, as it is an autoimmune disease. HIV infection weakens the immune system, particularly affecting CD4+ T-cells, leading to an increased susceptibility to various infections and autoimmune diseases, including lichen planus. HIV infection causes a reduction in the production of cytokines, which are essential for maintaining immune system homeostasis. This weakened immune system makes individuals with HIV more prone to developing LP.

**Why Each Wrong Option is Incorrect:**

A. Hepatitis C virus (HCV) infection: While HCV infection can cause liver inflammation, it does not specifically affect the immune system to the extent that HIV does. HCV primarily targets hepatocytes and leads to liver inflammation, cirrhosis, or hepatocellular carcinoma, rather than affecting T-cells and the immune system.

B. Human papillomavirus (HPV) infection: HPV is associated with the development of cervical cancer and other skin and genital warts. It does not directly affect the immune system or increase the risk of developing LP.

D. Hormonal imbalance: While hormonal changes can exacerbate LP symptoms, they are not responsible for causing the disease itself. LP is primarily an autoimmune disorder, and the link with hormonal imbalance is secondary to its impact on immune system function.

**Clinical Pearl:** HIV-positive patients should be closely monitored for the development of autoimmune diseases like lichen planus, as early diagnosis and management can improve their overall health and quality of life.

**Why LP is more common in HIV-positive patients:** The weakening of the immune system due to HIV infection leads to a higher prevalence of autoimmune diseases, such as lichen planus. HIV affects helper T-cells and the production of cytokines, which are essential for maintaining immune system homeostasis. The weakened immune system in HIV-positive patients makes them more susceptible to autoimmune diseases like lichen planus.