**Question:** Nasal polyps develop in patients with:

A. Allergic rhinitis
B. Chronic rhinosinusitis
C. Chronic urticaria
D. Sleep apnoea

**Core Concept:**
Nasal polyps are benign, non-cancerous, inflammatory growths that form within the mucous membranes of the nasal cavity and paranasal sinuses. They are often categorized as either allergic or non-allergic, depending on the underlying cause.

**Why the Correct Answer is Right:**
Nasal polyps primarily develop in patients with non-allergic and allergic forms of chronic rhinosinusitis (CRS). CRS is a chronic inflammation of the nasal mucosa that can lead to the formation of polyps due to ongoing immune responses and mucus production. In contrast, patients with chronic urticaria (C) experience skin rashes and not nasal polyps. Sleep apnoea (D) is a sleep disorder characterized by breathing interruptions during sleep, not a cause of nasal polyps.

**Why Each Wrong Option is Incorrect:**
Option A (Allergic rhinitis) is incorrect because it is an allergic condition characterized by sneezing, runny nose, and itching, but does not directly cause nasal polyps.

**Clinical Pearl / High-Yield Fact:**
Understanding the distinction between allergic and non-allergic rhinosinusitis is crucial for accurate diagnosis and treatment planning. Non-allergic rhinosinusitis may present with symptoms similar to allergic rhinitis but without a history of allergy. Treatment typically involves corticosteroid nasal sprays, while allergic rhinosinusitis may require antihistamines, intranasal corticosteroids, and anti-inflammatory medications.

**Correct Answer:**
The correct answer is B. Chronic rhinosinusitis (CRS). Nasal polyps develop in patients with chronic inflammation of the nasal mucosa, a condition known as chronic rhinosinusitis (CRS). CRS can be further categorized into non-allergic (B) and allergic (A) forms based on the presence of allergies in the patient history.