melanocytoma


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mel·a·no·cy·to·ma

(mel'ă-nō-sī-tō'mă),
1. A pigmented tumor of the uveal stroma.
2. Usually benign melanoma of the optic disc, appearing in markedly pigmented people as a small deeply pigmented tumor at the edge of the disc, sometimes extending into the retina and choroid; malignant metaplasia is rare.
[megalo- + cyto- + G. -oma; tumor]

mel·a·no·cy·to·ma

(mel'ă-nō-sī-tō'mă)
1. A pigmented tumor of the uveal stroma.
2. Usually benign melanoma of the optic disc, appearing in markedly pigmented people as a small deeply pigmented tumor at the edge of the disc, sometimes extending into the retina and choroid.
[melano- + cyto- + G. -oma; tumor]

melanocytoma

A harmless benign tumour, mainly of melanocytes, found on the OPTIC DISC, especially in black people.

melanocytoma

A benign, usually bilateral, pigmented tumour which is most commonly found in the optic disc arising from dendritic uveal melanocytes in the lamina cribrosa of the optic nerve head but may occur anywhere throughout the uveal tract. The patient's visual field presents an enlarged blind spot. The condition is more frequent in dark skinned people.
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(156,160-164,166,167) Although a number of explanations could be proposed to explain this (young age of the patients, potential misinterpretation of benign nodal nevi, therapeutic effect of sentinel node removal), the possibility that these lesions may represent a group of intermediate tumors (analogous to the pigmented epithelioid melanocytoma discussed below) was also raised.
Immunoreactivity for vimentin, S-100 protein, and HMB-45 is regularly present, melanocytomas in contradistinction to meningiomas--being EMA negative.
The growth of human skin malignant melanocytomas (SK-Mel-2, ATCC) was measured using the SRB method [19].
Among them, melanoma of the skin was discovered in 247 dogs (21.8% of the total number of examined dogs) and melanocytoma in 164 dogs (10% of the total number of examined dogs).
The nests and clusters of neoplastic cells as well as the sometimes high amount of dark brown pigmentation lead to the first assumption of a melanocytoma.
Ciliary body melanocytoma is also a deeply pigmented solid mass and more likely to display pigment dispersion and secondary glaucoma due to undergo central necrosis.
Differential diagnoses included a pigmented epithelioid melanocytoma, an agminated Spitz nevus, or a "low-grade" melanoma (Clark's level III, Breslow thickness 3.7 mm).
(14) These cells can be precursors to malignant melanoma, melanocytoma, pigmented schwannoma, and pigmented medulloblastoma.
Moreover, the presence of certain copy number alterations as detected by aCGH in diagnostically controversial or ambiguous tumors assessed histologically to be insufficient for an outright diagnosis of melanoma has helped support the concept of intermediate-grade melanocytic tumors (such as spitzoid melanocytic neoplasms and the pigmented epithelioid melanocytoma).
While, benign forms of these tumors are referred to as 'melanocytoma' in animals and nevus in humans, the malignant version is called malignant melanoma or simply 'melanoma' (Smith et al., 2002) in both the medical practices.
Their spectrum varies from benign to malignant and includes leptomeningeal melanocytosis, melanocytoma to its overtly malignant counterpart melanoma.