pathology
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Nevi presenting in the genitalia, inguinal region, umbilicus, axilla and breast may show considerable atypia. They should be readily recognised, often at scanning magnification but may be misdiagnosed as melanoma if the age of the patient and site of the lesion are not taken into account. So-called atypical acral nevus, ear & scalp nevi are…
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In the older literature this lesion has previously been called epithelioid blue nevus, animal type melanoma, pigment synthesizing melanoma & equine melanoma. Indeed, my cases of so-called animal type melanoma were re-classified as pigmented epithelioid melanocytoma during the preparation of the seminal paper on the topic by Zembowicz & Carney. Clinical features •Most common in…
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Clinical features •Proliferative nodules arise in giant (& occasionally small) congenital nevi •Develop in 2.9-19% of giant congenital nevi •Lesions can be single or multiple & are generally present at birth •Coloration varies from brown to black although deep seated lesions may not be apparent to the naked eye •The natural history is of spontaneous regression •Their importance is that they may be misdiagnosed by the unwary as neonatal melanoma •Congenital & neonatal melanoma is vanishingly…
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•Extremely rare often amelanotic, high-grade variant (based on the majority of documented cases representing metastases. The biological potential of primary tumors with rhabdoid features is uncertain owing to the paucity of reported cases) •Metastases & recurrent disease>>primary tumors •Characterized by pleomorphic tumor cells with large eosinophilic, hyaline globular inclusions and eccentric vesicular nuclei containing prominent nucleoli, mitoses often conspicuous •Inclusions predominantly composed of vimentin intermediate filaments •Immunophenotype is variable with possible loss of expression…
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Clinical fetaures •4% of melanoma cases in the USA •Predominantly affects sun damaged skin of the elderly •Malar region, nose, temple, forehead •Less of back of hand •Variably pigmented slowly growing macule with irregular borders & variable pigmentation •Papule or nodule formation indicates invasive tumor •Hypopigmentation is strongly suggestive of regression Histological features & immunohistochemstry •Epidermal atrophy & solar elastosis •Atypical melanocytes located predominantly along the basal layer of the epidermis, singly,…
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Definition A destinctive melanocytic tumor which may arise sporadically or less often represent a germline mutation in the tumor-suppressor gene BRCA1-associated protein-1 (BAP1). The latter is associated with an increased risk of devloping mesothelioma, uveal melanoma, cutaneous melanoma, Merkel cell carcinoma, basal cell carcinoma, meningioma & renal cell carcinoma Alternative nomenclature •BAP1-inactivated melanocytic tumors (BINT)…
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Dysplastic nevi can be sporadic (much more common) or multiple. In patients with dysplastic nevus syndrome (Familial Atypical Multiple Mole Melanoma syndrome) dysplastic nevi may number in hundreds. Patients with this syndrome are at a great risk of developing melanoma (de novo much more often than complicating a dysplastic nevus) Clinical features •Sporadic>>familial •10% of…
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A rare variant of melanoma which may exists as a pure subtype or represent part of a conventional melanoma where a more typical spindled morphology is present (this second subtype behaves no differently from any other melanoma). Clinical features •Rare sub-type (<4%) •High CSD •Head, neck & upper trunk++, •Scalp alopecia •+/- MIS •Around 50%…
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Two subtypes Clinical features •Usually slowly growing tumors •Predilection for the scalp •M>F •No age predilection & exceptionally, lesions can develop in children •High grade tumor probably related to delay in diagnosis & hence marked tumor thickness •Metastases develop in around 50% of cases to lymph nodes, lung & liver Histological features •Develops within a precursor lesion as one or more nodules of epithelioid or spindled cell melanoma •Or melanoma showing admixed blue nevus-like…
McKee Derm 