Diagnostic Workup for Melanonychia of the Big Toe to Rule Out Subungual Melanoma

Clinical Evaluation and Biopsy Technique

The American Academy of Dermatology recommends that the nail plate must be sufficiently removed to expose the underlying lesion, and the nail matrix must be sampled by a practitioner skilled in nail apparatus biopsy, with either excisional or incisional biopsy performed depending on lesion size 1, 2
The British Journal of Dermatology suggests documenting the site, size, presence of ulceration, bleeding, or nodular features, and photographing the lesion before biopsy 3, 4

The American Academy of Dermatology recommends removing the nail plate sufficiently to expose the underlying lesion and adequately sample the nail matrix 1, 2, 5
Excisional biopsy is preferred when feasible, encompassing the entire lesion, while incisional biopsy is acceptable for larger lesions, but must include adequate sampling of the nail matrix 1, 2
The pathologist should evaluate the specimen and report Breslow thickness, presence or absence of ulceration, margins of excision, and Clark level 1, 3, 5

The National Comprehensive Cancer Network or other guideline societies may recommend against routine imaging for stage I-II disease unless investigating specific signs or symptoms, and for stage IIB-IIC, chest radiograph is optional 6, 7
For clinically positive regional lymph nodes, confirmation with fine-needle aspiration or open biopsy is necessary before proceeding with definitive treatment 6, 7