**Question:** Extra mammary Paget's involves

A. Anogenital skin
B. Nipple skin
C. Genitourinary tract
D. Digestive system

**Core Concept:** Extra-mammary Paget's disease is a rare form of Paget's disease, typically seen in women. Paget's disease is characterized by the presence of epidermal cells with characteristic Pagetoid distribution (spreading outwards from the epidermis) in the absence of underlying breast cancer. It is associated with underlying ductal carcinoma in situ (DCIS) in about 70% of cases.

**Why the Correct Answer is Right:** Extra-mammary Paget's disease primarily involves the nipple and areola skin, which is option B (Nipple skin). This is because Paget's cells are found in the epidermis, and the nipple and areola skin are the most common sites for extra-mammary Paget's disease.

**Why Each Wrong Option is Incorrect:**

A. Anogenital skin (A) is incorrect because this type of Paget's disease is known as anal Paget's disease and is a separate entity with different underlying pathology.

C. Genitourinary tract (C) is incorrect because extra-mammary Paget's disease is not typically associated with genitourinary tract lesions.

D. Digestive system (D) is incorrect because extra-mammary Paget's disease primarily involves the skin and rarely involves the gastrointestinal tract.

**Clinical Pearl:** In cases where extra-mammary Paget's disease is suspected, a detailed clinical examination and imaging studies are crucial to identify underlying breast lesions. Invasive ductal carcinoma is the most common underlying breast cancer, followed by ductal carcinoma in situ (DCIS).

**Correct Answer:** Extra-mammary Paget's disease (Option B) is associated with underlying breast lesions, most commonly invasive ductal carcinoma (IDC) and ductal carcinoma in situ (DCIS). If Paget's disease is suspected, thorough clinical examination and imaging studies are essential to identify the underlying breast lesion.