**Question:** Osler's nodes are seen at:

A. Subcutaneous
B. Submandibular
C. Submental
D. Subcostal

**Core Concept:** Osler's nodes are a characteristic finding in systemic vasculitis, particularly in the setting of Wegener's granulomatosis. They are small, tender, red, and elevated subcutaneous nodules, usually located on the hands and feet.

**Why the Correct Answer is Right:** Osler's nodes are a manifestation of vasculitis, a group of diseases characterized by inflammation of blood vessels. In the context of Wegener's granulomatosis, these nodes are a result of the inflammation affecting small blood vessels (capillaries, arterioles, and venules) in the hands and feet. The subcutaneous location allows for easy detection and differentiation from other types of nodules or swelling.

**Why Each Wrong Option is Incorrect:**

A. Subcutaneous nodules are not specific to any particular disease or condition, making it too broad a location choice.
B. Submandibular nodes are located in the neck, far from the hands and feet, rendering this option irrelevant for the context of Osler's nodes.
C. Submental nodes are located in the neck, similar to submandibular nodes, making it an incorrect choice for the location of Osler's nodes.
D. Subcostal nodes are located in the abdominal wall, far from the hands and feet, making this option irrelevant for the context of Osler's nodes.

**Clinical Pearl:** Osler's nodes, along with Ritter's nodes, Weber-Christian nodules, and Purpura, collectively represent the "red, hot, swollen, and painful" signs of vasculitis, which are crucial for a clinical suspicion of Wegener's granulomatosis and prompts further evaluation and diagnosis.