Estudo do padrão dermatoscópico de cristas paralelas na região acral de pacientes com fototipo IV a VI

Abstract

Pigmented lesions, melanocytic or otherwise, represent a diagnostic challenge when they occur in acral skin. The main differential diagnosis is acral lentiginous melanoma. This form accounts for 10% of all cutaneous melanomas, and is the most prevalent type in the black population. Dermoscopy is a noninvasive diagnostic modality that aids in the early detection of melanoma, thus improving prognosis. In acral regions, the dermoscopic parallel ridge pattern has been reported as highly sensitive and specific for the diagnosis of acral lentiginous melanoma. However, this pattern has also been reported in some benign lesions, such as lentiginosis, dye pigmentation, and, rarely, in some nevi. Pigment is present on ridges in other dermoscopic patterns as well, such as homogeneous diffuse pigmentation and irregular diffuse pigmentation, which makes these patterns difficult to distinguish. Most studies on dermoscopy in acral melanoma have been conducted in series of Asian and Hispanic patients. This prompted our interest in studying a black-skinned patient population. The present study sought to evaluate the association between the dermoscopic parallel ridge pattern and diagnosis of acral lentiginous melanoma in patients with Fitzpatrick skin phototypes IV through VI. This was an observational, descriptive, cross-sectional study of patients treated at the Outpatient Dermatology Clinic of Hospital Universitário Pedro Ernesto, Universidade do Estado do Rio de Janeiro, Brazil. Thirty-one patients were included from August 2013 to March 2016. Two patients had two lesions each, for a total of 33 biopsies. Of these, 17 (51.5%) exhibited a dermoscopic parallel ridge pattern, 15 (45.5%) exhibited an irregular diffuse pigmentation pattern, and 1 (3%) exhibited homogeneous diffuse pigmentation. All lesions with a parallel ridge pattern were found to be benign on histopathological examination, as was the sole lesion with a homogeneous diffuse pigmentation pattern. Of the 15 lesions with an irregular diffuse pigmentation pattern on dermoscopy, two were diagnosed as acral lentiginous melanoma and one as atypical melanocytic hyperplasia. The parallel ridge pattern was not as accurate as expected for the diagnosis of acral lentiginous melanoma in the studied population.