In non-white populations, acral skin is the most prevalent site of malignant melanoma. Early melanomas of this anatomic site are often misdiagnosed as melanocytic nevi, which are not uncommon on acral skin. In fact, clinical and/or histopathological features of melanocytic nevi occasionally mimic those of early acral melanoma and vice versa, and thus differentiation of early acral melanoma from melanocytic nevus is sometimes very difficult for clinicians as well as for histopathologists. Our dermoscopic investigation has revealed that the parallel ridge pattern, a band-like pigmentation on the ridges of the skin markings, is highly specific to malignant melanoma in situ on acral volar skin. In the present study, we reviewed 22 acral melanocytic lesions that showed the parallel ridge pattern on dermoscopy but had very subtle clinical and/or histopathological presentations. We diagnosed 20 of them as early melanoma in situ by careful histopathological examination, which revealed histopathological features very similar to those seen in macular portions of overt acral melanoma, but fundamentally different from features found in melanocytic nevi on acral skin. In correspondence with their dermoscopic pattern, in these early lesions of acral melanomas, proliferation of solitary arranged melanocytes was mainly detected in the crista profunda intermedia, the epidermal rete ridge underlying the ridge of the skin marking. The two remaining lesions were diagnosed as possible cases of acquired melanocytic nevus because of the formation of well-demarcated nests of melanocytes in the epidermal rete ridges. We propose that a finding of preferential proliferation of solitary arranged melanocytes in the crista profunda intermedia is an important clue for the histopathological diagnosis of early phases of acral melanoma.
"They suggested that these histopathological findings differed from those of AMOF and were regarded as phase I of AML in situ, as described by Saida. Recently, Ishihara et al. suggested that predominant melanocytic proliferation in the crista profunda intermedia observed during histopathology is a critical finding for diagnosis of a very early phase of acral melanoma10. In our case, similar histopathologic features, with focal melanocytic proliferation, predominantly in the crista profunda intermedia, were observed on the peripheral brownish patch lesion surrounding the main melanoma lesion. "
[Show abstract][Hide abstract] ABSTRACT: Clinical guidelines suggest that suspicious pigmented lesions of the plantar or palmar area require biopsy for early detection of acral melanoma. We present here a case of acral lentiginous melanoma in which various melanocytic atypia was observed at each biopsy site, including focal melanocytic proliferation. We suggest that this atypical melanosis is part of a contiguous phase of invasive tumor growth, which is known as the very early stage of melanoma in situ. In addition, noninvasive dermoscopy has been effective for the early discovery of hidden lesions of acral melanoma.
Annals of Dermatology 08/2011; 23(3):400-4. DOI:10.5021/ad.2011.23.3.400 · 1.39 Impact Factor
"Oguichi and co-workers  also reported that parallel ridge pattern showed very high specificity and sensitivity for melanoma in situ on glabrous skin. Furthermore, some authors also reported that dermoscopy can identify early acral melanoma in situ before they are diagnosed by conventional clinical or histopathological criteria [14,15,16]. Recently, dermoscopic findings of ALM of nail apparatus were also analyzed [9,17]. "
[Show abstract][Hide abstract] ABSTRACT: Early stage recognition of acral lentiginous melanoma (ALM) is important for a better prognosis, but in-depth understanding and proper management of ALM in situ is complicated, because there are only a few reports, probably due to its rarity and diagnostic difficulty. We have reviewed our experience with seven patients who were diagnosed as having ALM in situ and discuss how to accurately diagnose and properly manage these rare lesions. Clinically the lesions showed black to brown discoloration of the nail with Hutchinson's sign and hyperpigmented macules on the heel with color variegation. All the lesions showed a diffuse lentiginous pattern of melanocytic proliferation with variable level of atypism along the dermoepidermal junction. Dermoscopic findings were available in three and revealed parallel ridge patterns. Confrontation of clinical and histopathologic findings was observed in three, and the lesions were not recognized or diagnosed as ALM in situ in the first place. Excision of the primary lesion with variable operative margin was done as an initial treatment. Recurrence was observed in three patients and one developed invasive ALM and lymph node metastasis. Integration of all available information concerning the clinical presentation, histopathology, and dermoscopic findings is very important and can lead to the best classification for correct diagnosis. Lack of knowledge upon clinical course and optimal margin to control ALM in situ provokes the need for further studies with longer follow up and larger number of cases.
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