Clinical and dermoscopic features of truly amelanotic plantar melanoma

Abstract

Currently, there are no specific clinical and dermoscopic features for diagnosing truly amelanotic plantar melanoma (TAPM). The present study aimed to investigate the dermoscopic features of all clinical variants of TAMPS and to evaluate their histopathological correlations. A retrospective analysis of prospectively collected data was carried out during a 10-year period (2003-2013). We analyzed the clinical data of 1321 patients, who had received a histological diagnosis of melanoma at the Melanoma Unit of the University of Florence. We selected the clinical and dermoscopic images of TAPMs and analyzed the presence of dermoscopic parameters. Incorrect preoperative diagnoses were analyzed to highlight peculiar dermoscopic features of pinkish plantar melanomas, the clinical diagnosis of which is extremely challenging for the dermatologist. Of all 1321 patients, 29 (24%) had TAPMs. Importantly, only 20.7% of patients with TAPMs had a correct preoperative diagnosis of suspicious melanocytic lesion. On the basis of the initial misdiagnosis, TAPMs were categorized as eczema-like, verruca-like, angioma-like lesions. Dermoscopically, all TAPMs showed the presence of a well-defined 'erythematous homogeneous area' with an atypical polymorphous vascular pattern with dotted, globular, and glomerular vessels. Our study highlights a crucial dermoscopic feature of TAPMs, the 'erythematous homogeneous area' that is characteristic of the plantar region, and, to our knowledge and experience, has not been described in nonacral amelanotic melanomas.