Naevus Dermoscopy — SCE Dermatology MCQ

Correct answer: C — Growing benign naevus (symmetrically distributed peripheral globules indicate active naevus growth from melanocyte nesting at the junction)

The correct answer is C, growing benign naevus (symmetrically distributed peripheral globules indicate active naevus growth from melanocyte nesting at the junction). A ring of regular, symmetrically distributed dots and globules confined to the periphery of an otherwise uniform melanocytic lesion reflects ongoing junctional melanocytic proliferation at the advancing edge, a recognised benign dermoscopic feature seen typically in children, adolescents and young adults whose naevi are still enlarging. The key discriminator is symmetry: the globules are evenly spaced around the whole circumference and the lesion retains overall architectural order, unlike the asymmetric, irregular globules of melanoma. This pattern therefore supports reassurance and monitoring rather than excision, provided the rest of the lesion shows no atypical features. Why the other options are wrong: B. Dermatofibroma: characteristically shows a central white patch (scar-like area) with a surrounding pigment network, not peripheral globules, and often has a positive dimple sign clinically. A. Seborrhoeic keratosis: shows comedo-like openings, milia-like cysts, and a well demarcated stuck-on border with a fissured or brain-like surface pattern rather than peripheral globules. E. BCC: displays arborising telangiectatic vessels, blue-grey ovoid nests and ulceration, features unrelated to a globular naevus pattern. D. Melanoma: peripheral globules in melanoma are asymmetrically distributed and irregular in size and shape, often with additional worrying features such as blue-white veil, atypical network or irregular pigmentation, contrasting with the regularity seen here. Key point: symmetrical, regularly distributed peripheral globules signify an actively growing benign naevus, whereas asymmetric or irregular peripheral globules should raise suspicion for melanoma.

Reference: DermNet NZ, Dermoscopy of Benign Melanocytic Lesions (Dermoscopy Course), https://dermnetnz.org/cme/dermoscopy-course/dermoscopy-of-benign-melanocytic-lesions