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Amelanotic Melanoma

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William G Campbell – One of the best experts on this subject based on the ideXlab platform.

  • primary treatment of choroidal Amelanotic Melanoma with photodynamic therapy
    Clinical and Experimental Ophthalmology, 2005
    Co-Authors: Mark J Donaldson, Lyndell L Lim, Alex C Harper, John Mackenzie, William G Campbell

    Abstract:

    The management of choroidal Melanoma involves a delicate balance between preserving vision and preventing metastasis. Plaque brachytherapy has become standard management of most small lesions; however, this can result in radiation retinopathy and optic neuropathy. Transpupillary thermotherapy avoids these side-effects; however, it can also result in visual loss and its effectiveness is limited in Amelanotic lesions. Photodynamic therapy with verteporfin has shown promise in animal studies of choroidal Melanoma, and has recently been used in the management of lesions that have failed to respond to conventional therapy. The authors report a case of primary treatment of a small choroidal Amelanotic Melanoma with photodynamic therapy using verteporfin.

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Daniel M Albert – One of the best experts on this subject based on the ideXlab platform.

  • spontaneous uveal Amelanotic Melanoma in transgenic tyr ras ink4a arf mice
    Archives of Ophthalmology, 2005
    Co-Authors: William H Tolleson, Jason C Doss, John R Latendresse, Alan Warbritton, William B Melchior, Lynda Chin, Richard R Dubielzig, Daniel M Albert

    Abstract:

    Objective To characterize a murine model of spontaneous Amelanotic Melanoma arising in the uvea of transgenic mice bearing a targeted deletion of the Ink4a / Arf tumor suppressor locus (exons 2 and 3) and expressing human H- ras controlled by the human tyrosinase promoter. Methods Ocular lesions developed in 20 (15.7%) of 127 male albino Tyr-RAS + Ink4a/Arf −/− transgenic FVB/N mice within 6 months, and were evaluated histologically and ultrastructurally. Results Uveal Melanomas were locally invasive but confined to the eye, with no evidence of metastasis. Tumor cells exhibited epithelioid and spindle-shaped morphological features and closely resembled the human counterpart. Melan-A, S100 and neuron-specific enolase expression were detected immunohistochemically. Melanosomal structures were detected using electron microscopy. The retinal pigment epithelium was intact above small Melanomas, and electron microscopy of the tumors failed to show the presence of basement membrane formation or desmosomes. Conclusion Spontaneous uveal malignant Melanomas occurring in male Tyr-RAS + Ink4a/Arf −/− transgenic mice arise within the choroid or ciliary body and share histopathological features characteristic of human uveal Melanoma. Clinical Relevance Uveal Melanoma research has benefited from xenograft models, but engineered mouse models of spontaneous uveal Amelanotic Melanoma will undoubtedly further our understanding of the genetic underpinning for this disease.

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Giovanni Pellacani – One of the best experts on this subject based on the ideXlab platform.

  • hyporeflective pagetoid cells a new clue for Amelanotic Melanoma diagnosis by reflectance confocal microscopy
    British Journal of Dermatology, 2014
    Co-Authors: A Losi, Caterina Longo, A M Cesinaro, Elisa Benati, Alexander Michael Witkowski, Pascale Guitera, Giovanni Pellacani

    Abstract:

    Summary
    Background

    Amelanotic Melanoma represents a diagnostic challenge both clinically and dermoscopically. Few studies based on case series have explored the possibility of using reflectance confocal microscopy (RCM) to diagnose Amelanotic Melanoma.

    Objectives

    To validate a new confocal feature, named hyporeflective pagetoid cells (HPCs), for the diagnosis of Amelanotic Melanoma.

    Methods

    A group of 20 Amelanotic Melanomas and a control population of nonpigmented melanocytic naevi (10), hypo/nonpigmented nonmelanocytic lesions (20) and pigmented Melanomas (20), imaged by RCM, were retrospectively evaluated. The presence of HPCs and other diagnosis-specific confocal features was assessed and correlated with histopathology.

    Results

    HPCs were present, and usually abundant, in the majority of Amelanotic Melanomas (85%). As expected, they were also observed in Spitz naevi. On histopathology, they were correlated with pagetoid infiltration of hypomelanotic melanocytes in all melanocytic lesions. Few nonmelanocytic lesions (three squamous cell carcinomas, two seborrhoeic keratoses and one basal cell carcinoma) showed the presence of HPCs. In these cases, they corresponded to enlarged or dyskeratotic keratinocytes by histopathology.

    Conclusions

    The identification of HPCs in the epidermis is a new parameter that is frequently found in Amelanotic Melanoma. Possible confounders are represented by atypical keratinocytes that can be present in nonmelanocytic lesions. However, the whole architecture and the presence of additional diagnostic criteria should be considered in order to obtain a correct diagnosis.

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