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Dr. Sampurna Roy MD
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Surgical-Pathology.com
INDEX: A-D ; INDEX: E-L ;INDEX: M-P ;INDEX: Q-Z ; FUNGAL DISEASE ; VIRAL DISEASE. |
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Melanocytic tumours 1. Acquired Melanocytic Naevus
Ancient Naevus
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| The lesion is
characterized by amelanotic ring upto several milimeters in width
around a melanocytic naevus.
Image Link(DermAtlas):click (Clinical D/D: Meyerson's Naevus -eczematous halo around the naevus). Histologically, a dense lymphocytic infiltrate is present in the dermis which may obscure the melanocytic component. Nevus cells are present in nests or singly within the lymphocytic infiltrate. The number of nevus cells depend on the stage at which the biopsy was taken. Some cells show cytological atypia. (D/D: In melanoma such a dense diffuse lymphocytic infiltrate is usually not present.) Some macrophages and factor XIIa-positive dendrocytes may be present in the infiltrate. In some cases, the melanocytes may be epithelioid in type and may display some cytological atypia. The lymphocytes are mostly CD8- positive lymphocytes. These cells express CD69 and tumour necrosis factor -alpha. Depigmented halo shows an absence of melanin pigment and melanocytes in the basal layer. (Both humoral and cell mediated immunity are involved in the rejection of nevus cells and formation of halo naevus.) Image Links1(Dr Weem) ; Image2 Halo nevus or halo phenomenon? A study of 142 cases.J Cutan Pathol. 1995;22(4):342-8.
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Pigmented melanocytic lesions causing diagnostic
problems Prognostic parameters of melanoma Superficial spreading melanoma |