Early acral melanoma in situ - Correlation between the parallel ridge pattern on dermoscopy and microscopic features
ABSTRACT 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.
- SourceAvailable from: InTechMelanoma in the Clinic - Diagnosis, Management and Complications of Malignancy, 08/2011; , ISBN: 978-953-307-571-6
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ABSTRACT: The dermatoscopic features of facial lentigo maligna (LM), facial lentigo maligna melanoma (LMM) and acral lentiginous melanoma (ALM) have been well described. This is the first description of the dermatoscopic appearance of a clinical series of cutaneous non-facial non-acral lentiginous growth pattern melanomas. To describe the dermatoscopic features of a series of cutaneous non-facial non-acral lentiginous growth pattern melanomas in an Australian skin cancer practice. Single observer retrospective analysis of dermatoscopic images of a one-year series of cutaneous non-facial, non-acral melanomas reported as having a lentiginous growth pattern detected in an open access primary care skin cancer clinic in Australia. Lesions were scored for presence of classical criteria for facial LM; modified pattern analysis ("Chaos and Clues") criteria; and the presence of two novel criteria: a lentigo-like pigment pattern lacking a lentigo-like border, and large polygons. 20 melanomas occurring in 14 female and 6 male patients were included. Average patient age was 64 years (range: 44-83). Lesion distribution was: trunk 35%; upper limb 40%; and lower limb 25%. The incidences of criteria identified were: asymmetry of color or pattern (100%); lentigo-like pigment pattern lacking a lentigo-like border (90%); asymmetrically pigmented follicular openings (APFO's) (70%); grey blue structures (70%); large polygons (45%); eccentric structureless area (15%); bright white lines (5%). 20% of the lesions had only the novel criteria and/or APFO's. Single observer, single center retrospective study. Cutaneous non-facial non-acral melanomas with a lentiginous growth pattern may have none or very few traditional criteria for the diagnosis of melanoma. Criteria that are logically expected in lesions with a lentiginous growth pattern (lentigo-like pigment pattern lacking a lentigo-like border, APFO's) and the novel criterion of large polygons may be useful in increasing sensitivity and specificity of diagnosis of these lesions. Further study is required to establish the significance of these observations.01/2014; 4(1):77-82. DOI:10.5826/dpc.0401a13
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ABSTRACT: Maligne Melanome bilden eine heterogene Gruppe von Tumoren, die in Abhängigkeit von ihrer anatomischen Lokalisation und der UV-Exposition charakteristische genetische Aberrationen aufweisen. Eine Aktivierung des Mitogen-aktivierte-Proteinkinase- (MAPK-)Signaltransduktionsweges findet sich bei einem Großteil aller Melanome, wobei entweder eine somatische Missense-Mutation von BRAF oder deutlich seltener eine Mutation von N-RAS vorliegt. Der Verlust der beiden Produkte des CDKN2A-Gens, p16ARF und p14INK4a, oder die Amplifikation von Microphthalmia-assoziiertem Transkriptionsfaktor (MITF) prädisponieren ebenfalls zur Melanomentwicklung. BRAF-Mutationen werden vor allem in Melanomen von intermittierend UV-exponierter Haut beobachtet. Akrale und mukosale Melanome sowie solche von chronisch UV-geschädigter Haut sind durch distinkte Muster chromosomaler Aberrationen mit häufigen Amplifikationen sowie Alterationen des KIT-Gens gekennzeichnet, während BRAF-Mutationen in diesen Lokalisationen selten nachweisbar sind. Uveamelanome zeigen wiederkehrende Chromosomenverluste (1p, 3, 6q) und Zugewinne (6p, 8q), aber kaum BRAF-Mutationen. Bis heute haben molekulare Untersuchungen noch keinen festen Platz in der Routinediagnostik des malignen Melanoms. Die Entwicklung gezielter molekularer Therapeutika wird es aber zukünftig notwendig machen, mittels molekularpathologischer Methoden diejenigen Melanompatienten zu identifizieren, die von einer bestimmten Therapie am ehesten profitieren. Malignant melanomas make up a heterogeneous group of tumors characterized by particular genetic aberrations depending on their anatomic localization and UV exposure. Activation of the mitogen-activated protein kinase (MAPK) signaling pathway is found in the majority of melanomas, with either somatic missense mutations of BRAF or, considerably more rarely, mutations of N-RAS. The loss of both products of the CDKN2A gene, proteins p16ARF and p14INK4a, or amplification of microphthalmia-associated transcriptional factor (MITF) are also predisposing factors in the development of melanoma. BRAF mutations are observed mainly in melanomas on skin liable to intermittent UV exposure. Acral and mucosal melanomas, and also melanomas on skin damaged by chronic exposure to the sun are characterized by distinct patterns of chromosomal aberrations with frequent amplifications and alterations of the KIT gene, while BRAF mutations are rarely found in these sites. Uveal melanomas show recurrent chromosomal losses (1p, 3, 6q) and gains (6p, 8q), but mutations of BRAF are hardly ever found. So far, ancillary molecular studies are not regularly applied in the routine diagnostic procedures performed when malignant melanoma is suspected. In the future, however, the development of targeted molecular therapies will require that molecular pathological techniques are used to identify the melanoma patients who will most probably benefit from a particular therapy.Der Pathologe 11/2007; 28(6):474-478. DOI:10.1007/s00292-007-0942-6 · 0.64 Impact Factor