**Core Concept**
Melanoma of the anal canal is a rare but aggressive form of cancer that originates from the melanocytes in the anal mucosa. It is essential to understand the unique characteristics and clinical presentation of this condition to diagnose and manage it effectively.

**Why the Correct Answer is Right**
Melanoma of the anal canal accounts for approximately 1-2% of all anal cancers and is more common in women. The symptoms often include anal pain, bleeding, and a palpable mass. Early detection is crucial due to the aggressive nature of this cancer. The anal melanoma is most commonly located in the posterior anal canal, and its prognosis is generally poor, especially if not diagnosed at an early stage.

**Why Each Wrong Option is Incorrect**
**Option A:** Anal melanoma is more common in men.
* This is incorrect because anal melanoma is more common in women.

**Option B:** Melanoma of the anal canal originates from the squamous epithelium.
* This is incorrect because anal melanoma originates from the melanocytes, which are a type of neuroectodermal cell.

**Option C:** The most common symptom of anal melanoma is pruritus.
* This is incorrect because the most common symptoms of anal melanoma are anal pain and bleeding, not pruritus.

**Clinical Pearl / High-Yield Fact**
Anal melanoma is often diagnosed at a late stage due to its rarity and nonspecific symptoms, making it essential for clinicians to maintain a high index of suspicion for this condition in patients presenting with anal pain or bleeding.

**Correct Answer:** D.