Clinical and dermoscopic characteristics of amelanotic melanomas that are not of the nodular subtype

Abstract

Background: Amelanotic melanomas remain challenging to diagnose.

Objective: To analyze and describe the clinical and dermoscopic characteristics of amelanotic melanomas that are not of the nodular subtype.

Patients/methods: We conducted a retrospective review of 20 consecutively diagnosed amelanotic melanomas. The clinical and dermoscopic images of pathologically confirmed amelanotic melanomas that were not of the nodular subtype were analyzed. In addition, the clinical diagnosis and the reasons why these lesions were biopsied were examined.

Results: All 20 amelanotic melanomas were erythematous and lacked any of the clinical ABCD features commonly attributed to melanoma. The lesions appeared clinically to be relatively symmetric with regular borders and manifesting a circular to oval morphology. Dermoscopically, all lesions manifested polymorphous vascular pattern.

Conclusions: Amelanotic melanomas that are not of the nodular subtype often present as clinically symmetric erythematous lesions. Therefore, it is important to consider AMs in the differential diagnosis of isolated and persistent erythematous outlier lesions, even if they are symmetric in appearance. Additionally, the presence of a polymorphous vascular pattern seen with dermoscopy can facilitate in correctly identifying these melanomas.