Dermatology MCQ - Infiltrative and Neoplastic Disorders - Naevus of Ito

A 28-year-old man presents with a large, bluish-gray, ill-defined patch on his right shoulder and supraclavicular area. He reports it has been present since his teenage years and has remained stable in size and color. On palpation, the lesion is entirely macular. The rest of his skin examination is unremarkable, with no similar lesions in the periorbital area and no scleral pigmentation. What is the most accurate statement regarding the diagnosis and associated risks of this lesion?

A. It is a persistent lesion with histology identical to a blue nevus, carrying a significant risk of transformation into melanoma.
B. It is a form of dermal melanocytosis that is cosmetically concerning but carries no risk of systemic complications or malignancy.
C. It shares the same embryological origin and malignant potential as a Becker's nevus, requiring annual surveillance.
D. It is histologically characterized by dermal dendritic melanocytes and shares the same low risk of ocular and cutaneous complications as Naevus of Ota.
E. It is a vascular malformation that may be associated with soft-tissue hypertrophy of the affected limb.

Correct Answer: D. It is histologically characterized by dermal dendritic melanocytes and shares the same low risk of ocular and cutaneous complications as Naevus of Ota.

Answer and Explanation

The correct answer is D. This question describes a classic Naevus of Ito. The key clinical clues are the location (shoulder, supraclavicular area, and deltoid region—the "acromioclavicular" distribution), the characteristic bluish-gray color, and the congenital or early-onset presentation. Naevus of Ito is embryologically and histologically identical to Naevus of Ota, differing only in its anatomical location. Therefore, it carries the same, albeit low, risks.

Why the Other Options are Incorrect:

• A. It is a persistent lesion with histology identical to a blue nevus, carrying a significant risk...: This is incorrect. While both are dermal melanocytic lesions, their histology is distinct. A blue nevus shows densely packed, often spindled melanocytes with heavy melanin, whereas Naevus of Ito shows more sparsely distributed dendritic melanocytes in the dermis. The risk of melanoma, while present, is very low, not "significant."

• B. It is a form of dermal melanocytosis that is cosmetically concerning but carries no risk...: This is incorrect and a common point of confusion. While Naevus of Ito has a lower reported rate of complications than Naevus of Ota (due to the absence of critical structures like the eye), case reports and series have documented the development of malignant melanoma within these lesions. Therefore, it is not accurate to say it carries no risk.

• C. It shares the same embryological origin and malignant potential as a Becker's nevus...: This is incorrect. A Becker's nevus is an entirely different entity—an acquired, pigmented hamartoma of the skin characterized by hyperpigmentation and hypertrichosis, with no increased malignant potential. It is not a dermal melanocytosis.

• E. It is a vascular malformation that may be associated with soft-tissue hypertrophy...: This incorrectly describes Klippel-Trenaunay syndrome or a capillary malformation. The bluish color of Naevus of Ito is melanocytic, not vascular.

Additional High-Yield Information for Exams:

• Histopathology: Identical to Naevus of Ota and Mongolian spots. It shows slender, dendritic melanocytes scattered freely in the upper and mid-dermis, oriented parallel to the skin surface. There is no nesting or junctional component.

• Differential Diagnosis:

  • Mongolian Spot: Lumbosacral location, usually resolves.

  • Naevus of Ota: Periorbital distribution, involves sclera.

  • Blue Nevus: A smaller, more circumscribed, often darker blue-black papule or nodule.

  • Post-inflammatory Hyperpigmentation: Would have a history of prior inflammation or trauma.

• Associated Conditions & Prognosis:

  • Persistence: The lesion is almost always permanent and may darken slightly during puberty.

  • Malignancy Risk: The risk of malignant melanoma arising within a Naevus of Ito is very low but well-documented in the literature. This risk is lower than for Naevus of Ota, primarily because the latter also carries a risk of ocular melanoma.

  • Associated Syndromes: It is usually an isolated finding. Rarely, it can be associated with Naevus of Ota in the same patient.

• Management & Rationale:

  • Rationale: The main goals are patient reassurance, documentation, and prudent long-term monitoring for any signs of malignant change, given the rare but real risk.

  • First-line: Clinical diagnosis and baseline photography to document stability. Patient education on the signs of melanoma (change in color, size, texture, or the development of a nodule) is crucial.

  • Ophthalmology Referral: Unlike Naevus of Ota, routine ophthalmologic screening is not required unless there is concomitant scleral pigmentation suggesting a combined lesion.

  • Cosmetic Treatment: Q-switched lasers (e.g., Nd:YAG) are the treatment of choice for patients seeking cosmetic improvement and can be very effective.