Acral lentiginous melanoma mimicking benign disease: The Emory experience

Background: Plantar and subungual melanoma exhibits a higher misdiagnosis rate relative to other anatomic sites. Misdiagnosis and delay in diagnosis are statistically associated with poorer patient outcome. Awareness of atypical presentations of acral melanoma may, thus, be important to decrease misdiagnosis rates and improve patient outcome. Methods: We conducted a retrospective case review of plantar or lower-extremity subungual melanoma performed at Winship Cancer Center, a tertiary care, referral center affiliated with Emory University, between 1985 and 2001. Results: A total of 53 cases of plantar or lower-extremity subungual melanoma were identified. Of 53 cases with a final diagnosis of melanoma, 18 were initially misdiagnosed. Misdiagnoses included wart, callous, fungal disorder, foreign body, crusty lesion, sweat gland condition, blister, nonhealing wound, mole, keratoacanthoma, subungual hematoma, onychomycosis, ingrown toenail, and defective/infected toenail. Of the 18 misdiagnosed cases, 9 were clinically amelanotic. Conclusion: Awareness that amelanotic variants of acral melanoma may assume the morphology of benign hyperkeratotic dermatoses may increase the rate of correct diagnosis and improve patient outcome.