Review Question - QID 220070

Figure A demonstrates a fingernail with a Hutchinson's sign. This physical examination finding is highly suggestive of a subungual melanoma (Answer 4).

Melanomas are aggressive dermatologic malignancies that originate from neural crest-derived melanocytes. They are most common in the 50-70 year old age group. In the hand, they most often occur in the thumb. In cases of subungual melanoma, the nail is frequently rendered dystrophic and is more prone to trauma. Hutchinson's sign is a physical exam finding in which the pigmentation spreads onto the nail folds, paired with nail lifting. If melanoma is suspected, the next step in the workup is a biopsy. The depth of invasion most determines the prognosis of melanoma. Subungual melanoma has a poor prognosis overall, with a 5-year survival of 40-60%.

Graham et al. reviewed dermatologic conditions pertinent to hand surgeons. They discuss that subungual melanomas can present as nail discoloration, a nonhealing wound, mass, bleeding, or nail deformity. The authors highlight that subungual melanomas have a lower 5-year prognosis due to delay in diagnosis. The authors conclude that there should be a low threshold for for biopsy.

Dooley et al. reviewed subungual tumors and their presentation, workup, and treatment. They discuss that subungual melanomas are most often present in the thumb. They go on to highlight the surgical management of subungual melanoma and that amputation is frequently recommended due to difficulty in achieving appropriate surgical margins. They go on to state that lymph node biopsy is not required in cases with lesion thickness below 1.5 mm.

Figure A demonstrates Hutchinson's sign with pigmentation spreading to the proximal nail fold.

Incorrect Answers:
Answer 1: Squamous cell carcinoma does not typically present with pigmentation of the nail plate.
Answer 2: Onychomycosis is a fungal infection in the vicinity of the nail bed. It typically presents with nail plate thickening, separation, and yellow or brown discoloration.
Answer 3: A subungual hematoma would be unlikely in the absence of trauma. In addition, the hematoma would be contained under the nail plate.
Answer 5: Psoriasis of the nail typically presents with pitting, separation, and yellow or brown discoloration.