Dermatology MCQ - Infiltrative and Neoplastic Disorders - Benign melanocytic nevus

A 28-year-old woman requests evaluation of a mole near her areola that she states has been present and unchanged for many years. On examination, there is a 4-mm, uniformly light-brown, soft, papillomatous papule at the border of the areola. It is symmetrical with smooth borders. The patient is otherwise healthy and has no personal or family history of melanoma. What is the most appropriate management?

A. Perform a shave biopsy to rule out Paget's disease of the breast, given the location.
B. Reassure the patient that this is a benign melanocytic nevus and no intervention is needed.
C. Schedule a punch biopsy to assess for underlying ductal carcinoma in situ.
D. Refer the patient urgently for a mammogram to evaluate for an associated breast malignancy.
E. Recommend complete excision with 2-mm margins due to the high-risk location.

Correct Answer: B. Reassure the patient that this is a benign melanocytic nevus and no intervention is needed.

Answer and Explanation

The correct answer is B. This question describes a classic, benign-appearing melanocytic nevus. The key clinical clues are the long-standing stability, small size, uniform color, soft texture, and symmetrical, papillomatous architecture. These are all features of a benign compound or intradermal nevus. The location on the breast, including the areola, is a common site for benign nevi. In the absence of any atypical clinical features (the ABCDEs of melanoma) or a concerning history, reassurance is the standard of care.

Why the Other Options are Incorrect:

• A. Perform a shave biopsy to rule out Paget's disease...: This is incorrect. Paget's disease of the breast typically presents as a unilateral, eczematous, scaly, or crusted plaque on the nipple/areola, not a stable, pigmented, papillomatous papule. A shave biopsy would be an inappropriate and unnecessary procedure for this lesion.

• C. Schedule a punch biopsy to assess for underlying ductal carcinoma in situ: This is incorrect. Ductal carcinoma in situ (DCIS) is not a clinical diagnosis of a skin lesion; it is an internal breast pathology. A benign-appearing skin nevus has no correlation with DCIS and does not warrant a biopsy for this reason.

• D. Refer the patient urgently for a mammogram...: This is incorrect. There is no established link between a benign-appearing melanocytic nevus on the skin and an underlying breast carcinoma. An urgent referral for imaging is not indicated based on this finding alone.

• E. Recommend complete excision... due to the high-risk location: This is incorrect. While the breast is a site where melanoma can occur, it is not considered a "high-risk" anatomical location like the scalp or acral sites in the same way. A lesion with classic benign features and a history of stability does not require excision based solely on its location on the breast.

Additional High-Yield Information for Exams:

• Histopathology: Nevi on the breast are typically compound or intradermal nevi. They may often have a papillomatous (skin tag-like) or endophytic architecture. They follow the same histological rules as nevi elsewhere: symmetry, maturation of melanocytes with descent into the dermis, and lack of significant atypia.

• Differential Diagnosis: The main differential for a pigmented lesion on the breast includes:

  • Melanocytic Nevus: As described.

  • Seborrhoeic Keratosis: Often more "stuck-on" and waxy, with a verrucous surface and horn pseudocysts.

  • Melanoma: The diagnosis to rule out if any feature is atypical. Key warning signs would be change, irregular color, irregular borders, or symptoms like itching or bleeding.

  • Paget's Disease of the Breast: Presents as a unilateral, eczema-like change of the nipple/areola, often with itching, burning, or ulceration. It is not typically a simple papule.

• Prognosis: A benign melanocytic nevus on the breast has an excellent prognosis and the same very low malignant potential as a nevus anywhere else on the body.

• Management & Rationale:

  • Rationale: The goal is to avoid overtreating a benign lesion while remaining vigilant for signs of melanoma.

  • First-line for a classic lesion: Clinical diagnosis and reassurance. Documenting the lesion in the patient's record can be helpful for future reference.

  • Biopsy/Excision Indications: The criteria are the same as for any other nevus: change according to the patient (Evolution) or the presence of any clinical features of melanoma (Asymmetry, Border irregularity, Color variation, Diameter >6mm). If there is any doubt, a conservative excision for pathological diagnosis is prudent.