Atypical melanosis of the foot showing a dermoscopic feature of the parallel ridge pattern

Abstract

A 62-year-old male Turkish patient had a pigmented lesion on the sole with a 10-year history. It was an asymmetrical macular lesion with an irregular border and irregular brown pigmentation and had a diameter of 1.2 cm x 1.7 cm. Dermoscopy revealed a parallel ridge pattern and an abrupt cut-off of pigmentation on the upper edge. Histologically lentiginous hyperplasia decorated by innocent melanocytes and scattered melanocytic proliferation with slight to moderate cytological atypia were seen. Atypical melanocytes were very scattered and it was insufficient to call it a melanoma in situ. A second finding was a microvascular proliferation located in the papillary dermis. There was no sign of regression such as fibrous tissue or host reaction. Atypical melanosis of the foot has rarely been reported in the published work, which are from Japan and Korea. This case is presented to emphasize the significance of this rare entity which has recently been reported to be a very early phase of acral melanoma.

Reassessment of histopathology and dermoscopy findings in 145 Japanese cases of melanocytic nevus of the sole: Toward a pathological diagnosis of early‐stage malignant melanoma in situ

“…Recently, Karaarslan et al stated that atypical melanosis of the foot demonstrated a parallel ridge pattern dermoscopically, as well as lentiginous hyperplasia of melanocytes mainly in the crista profunda intermedia histopathologically, with slight to moderate cytological atypia. 21 Actually, these findings are similar to one of our findings of early-stage MM in situ, which is irregular distribution of solitary melanocytes at the crista profunda intermedia region. In addition, they also mentioned in the paper that the possibility of a very early phase of acral melanoma in situ cannot be ruled out for sure.…”

“…20 'Atypical melanosis of the foot' is also used in the sole. 21,22 However, only a few histological data are available for these lesions. Recently, Karaarslan et al stated that atypical melanosis of the foot demonstrated a parallel ridge pattern dermoscopically, as well as lentiginous hyperplasia of melanocytes mainly in the crista profunda intermedia histopathologically, with slight to moderate cytological atypia.…”

Benign dermoscopic parallel ridge pattern in plantar hyperpigmentation due to capecitabine

“…Dermoscopic findings from acral pigmented lesions are sometimes confusing. In recent years, various authors have highlighted parallel ridge pattern not only in acral melanoma but also in certain benign plantar lesions, such as congenital or acquired acral nevi, subcorneal hemorrhage, dye-related pigmentation and drug-induced hyperpigmentation, especially in patients with phototypes III–VI [ 13 – 17 ]. In particular, Fracaroli et al emphasised the importance of obliteration of eccrine gland ducts by neoplastic proliferation of melanocytes in distinguishing malignant and benign acral pigmented lesions with parallel ridge pattern [ 13 ].…”

Acral Lentiginous Melanoma Developing during Long-standing Atypical Melanosis: Usefulness of Dermoscopy for Detection of Early Acral Melanoma

“…Yamaura and colleagues have indicated that dermoscopic observations may be superior to histopathologic methods for the detection of early lesions of acral melanoma owing to the specificity of the parallel ridge pattern during detection of acral melanoma in the histopathologically unrecognizable early-development phase13. Recently, in another interesting report by Kilinc Karaarslan et al, dermoscopic features of the parallel ridge pattern were also shown in AMOF14. These findings support the suggestion that dermoscopic findings can be more critical in a histopathologically incredible early phase of malignancy.…”