Misdiagnosis and Clinical Insights into Acral Amelanotic Melanoma-A Systematic Review

BACKGROUND

Acral amelanotic melanomas (AAMs), a rare subset of melanomas located on acral sites such as the palms, soles, and subungual areas, are diagnostically challenging due to their lack of typical pigmentation and often benign clinical appearance. Misdiagnosis is common, leading to delays in treatment and potentially worse outcomes. This systematic review aims to synthesise evidence on cases of AAM initially misdiagnosed as other conditions, to better understand their clinical and epidemiological characteristics, diagnostic pitfalls, and management strategies.

METHODS

A comprehensive search of the MEDLINE/PubMed, EMBASE, and SCOPUS databases was conducted up to March 2024. Case reports and small case series of AAMs initially misdiagnosed as other conditions were included. Data on patient demographics, clinical presentation, and diagnostic methods were collected and analyzed.

RESULTS

Of the 152 records identified, 26 cases from 23 articles met the inclusion criteria. A demographic analysis revealed that the gender distribution appears to be perfectly balanced, with an age range of 38 to 91 years. Misdiagnoses included non-healing ulcers or traumatic lesions (37.5%), benign proliferative lesions (29.2%) and infectious lesions (20.8%). The foot was the most affected site (53.8%). Notably, a histological evaluation was performed in 50% of cases involving the upper extremities, in contrast to only 7.1% of cases involving the foot and 0% of cases of the heel. This discrepancy suggests a reluctance to perform biopsies in the lower extremities, which may contribute to a higher misdiagnosis rate in these areas.

CONCLUSIONS

The underutilization of biopsy in the diagnosis of lower extremity lesions contributes significantly to the misdiagnosis and delay in treatment of AAMs. Especially when the clinical assessment and dermoscopy are inconclusive, biopsies of suspicious lesions are essential. Immunohistochemistry and markers such as PRAME are critical in differentiating melanoma from other malignancies such as clear cell sarcoma. This review highlights the need for increased vigilance and a proactive diagnostic approach to increase early detection rates and improve prognostic outcomes.

Acral Amelanotic Melanoma Mimicking a Foot Ulcer

Acral amelanotic melanoma can be difficult to diagnose and is often clinically aggressive. The present report describes a case of an acral amelanotic melanoma presenting as a non-healing wound after mimicking a plantar wart for two years. The decision to biopsy a borderline-suspicious lesion on the lower extremity in an elderly individual must be weighed carefully, as lower extremity biopsy carries a risk of poor wound healing and other complications. We discuss clinical and epidemiologic features that can assist in deciding when to perform a biopsy in this setting and can improve the early detection of acral amelanotic melanoma.