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Histology of Melanoma

Contributed by Irma Gimenez-Conti, Steven Kazianis, Rodney Nairn, Don Morizot, and Ron Walter

Kazianis, S., Gimenez-Conti, I., Trono, D., Pedroza, A., Chovanec, L., Morizot, D.C.,
Nairn, R.S., and R.B. Walter (2001) "Genetic Analysis of MNU-Induced Neoplasia
within Xiphophorus Hybrid Fish." Marine Biotechnology 3(S1): 37-44.


Melanotic Hyperpigmentation Cross section of the caudal peduncle showing hyperpigmentation restricted to the integument (70 x).
irma1b Pre-cancerous Melanosis Fish skin showing aggregations of pigmented cells along the skin-dermis junction, around the scales, but sparse in the dermis (175 x).
irma2a Melanocytic Melanoma This exophytic tumor shows the penetration of melanocytes into the dermis but the lack of invasiveness into the underlying muscle tissue.
irma2b A higher magnification showing the predominant type of tumor cell, dendritic or spindle shaped. Their nuclei are oval and regular, and some cells are heavily pigmented (250 x).
irma2c Spindle Cell Type Melanoma This tumor shows heavily pigmented spindle cells (175 x).
irm2d Higher magnification showing fusiform cells with elongated nuclei and abundant melanin in the cytoplasm (500 x).
irm3a Epithelioid-Cell Type Melanoma Exophytic growth composed mostly of epithelioid cell types. Blood vessels are sparse throughout the whole tumor (70 x).
irm3b Higher magnification shows cuboidal-shaped cells with oval nuclei and dusty cytoplasmic melanin pigment (1000 x).
irm3c Melanophore-Macromelanophores Polymorphic Melanoma Cross section of a heavily pigmented tumor. Pigmented cells are invading the musculature (70 x).
irm3d Amelanotic Melanoma This tumor is located entirely in the dermis and do not invade the musculature. Most cells do not contain melanin, but in some small areas that are lightly pigmented cells (125 x).