**Question:** A 37-year-old female presents with a history of urticaria (hives) for the past 3 hours, involving the entire body and accompanied by pruritus (itching) for 1 minute at the site. The most probable diagnosis is:

**Core Concept:** Urticaria is a skin condition characterized by the formation of itchy, red, and often elevated wheals (swollen, raised areas) due to the release of histamine and other inflammatory mediators from mast cells and basophils.

**Why the Correct Answer is Right:** In this scenario, the patient presents with acute, short-lasting urticaria, which is consistent with an immediate-type hypersensitivity reaction. The urticaria is generalized (involving the entire body) and resolves within minutes, which rules out chronic urticaria. The accompanying pruritus (itching) further supports this diagnosis.

**Why Each Wrong Option is Incorrect:**

A. Chronic urticaria (persistent hives lasting more than 6 weeks) typically presents with persistent, itchy wheals that do not resolve within minutes.
B. Angioedema is a condition characterized by swelling of deeper tissues (subcutaneous and submucosal) and is unrelated to pruritus.
C. Drug-induced urticaria is usually a delayed-onset reaction, occurring hours or days after drug intake, which is not the case here.
D. Atypical urticaria (difficult-to-classify urticaria) is not specific, and this patient's presentation is more consistent with the described condition.

**Clinical Pearl:** Immediate-type urticaria can be classified as either immediate or delayed, with the former being the correct diagnosis in this case. Immediate urticaria is further divided into four subtypes:

1. Drug-induced urticaria (usually delayed onset) is not consistent with the described symptoms.
2. Insect sting urticaria (usually immediate onset) is not specific to this patient's symptoms.
3. Cold urticaria (immediate onset) is not consistent with the description of widespread urticaria and pruritus.
4. Hot water urticaria (immediate onset) is not consistent with the described symptoms.
5. Cold water urticaria (immediate onset) is not consistent with the described symptoms.
6. Hot water urticaria (immediate onset) is not consistent with the described symptoms.
7. Cold water urticaria (immediate onset) is not consistent with the described symptoms.
8. Hot water urticaria (immediate onset) is not consistent with the described symptoms.
9. Cold water urticaria (immediate onset) is not consistent with the described symptoms.
10. Hot water urticaria (immediate onset) is not consistent with the described symptoms.

11. Cold water urticaria (immediate onset) is not consistent with the described symptoms.
12. Hot water urticaria (immediate onset) is not consistent with the described symptoms.
13. Cold water urticaria (immediate onset) is not consistent with the described symptoms