Dermatology

Melanoma

Malignant tumour of melanocytes with high metastatic potential if diagnosed late; UV exposure, fair skin and BRAF/NRAS/KIT mutations drive risk. Early detection saves lives.

Last reviewed 26 Jun 2026 - MedicoMedics editorial team

Pathophysiology

UV-induced DNA damage; ~50% harbour BRAF V600E mutation. Subtypes: superficial spreading (most common), nodular, lentigo maligna, acral lentiginous.

Sources: NCCN Melanoma 2024; KEYNOTE-054 (NEJM 2018;378:1789)

Presentation

ABCDE: Asymmetry, Border irregularity, Colour variation, Diameter >6 mm, Evolving. Ugly duckling sign; new nail streak or acral lesion.

Diagnosis

Full excisional biopsy with narrow margins; report Breslow depth, ulceration, mitotic rate. Sentinel node biopsy for T1b or thicker.

Management

Wide local excision (margin by Breslow). Adjuvant: anti-PD-1 (pembrolizumab, nivolumab) for stage III/IV; BRAF+MEK inhibitors (dabrafenib+trametinib) for BRAF V600E. Ipilimumab-nivolumab for high-risk metastatic.

Sample USMLE-style MCQs

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Question 1

A 50-year-old with 8-mm asymmetric brown-black lesion on back. Best diagnostic step?

Question 2

Which mutation drives ~50% of cutaneous melanomas?

Question 3

Adjuvant therapy for resected stage III melanoma?

Question 4

Which subtype has worst prognosis for thickness?

Question 5

Which sign warns of subungual melanoma?

References

Primary guidelines and peer-reviewed sources used for this entry. Reviewed 26 Jun 2026 by MedicoMedics editorial team.

Frequently asked

Most important prognostic factor?

Breslow tumour thickness.

When SLN biopsy?

T1b (>=0.8 mm or ulcerated) or thicker.

BRAF-targeted therapy?

Dabrafenib + trametinib for V600E-mutant metastatic disease.

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