| Melanotic Tumors |
MMM |
Melano-Macromelanophoro Polymorphic Melanoma |
These tumors
are very heterogeneous, with heavily and lightly pigmented areas.
They are mixed tumors containing different cell types, including melanocytes,
epithelioid-like cells, melanophores, and macromelanophore cells.
Many also encompass groups of large fat-containing cells, especially
those appearing ventrally on the body. Any one of these cells may
constitute the predominant cell type; usually, different cell types
predominate in different areas of the tumor. |
MM |
Melanocytic Melanoma |
 These
tumors are characterized histologically by a proliferation of melanocytes.
These cells are dendritic in shape and contain variable amounts of
pigment. These melanomas may invade and destroy the muscle bundles
to different degrees.
|
SCM |
Spindle-Cell Type Melanoma |
These tumors contain spindle cells that extend into the dermis. Some
tumors invade the muscles, while others were confined to the dermis.
In the latter case, tumors may show different degrees of pigmentation. |
ECM |
Epithelioid-Cell Type Melanoma |
 These
tumors are usually less heavily pigmented and formed by cells morphologically
resembling epithelial cells. They are polyhedral cells with large
nuclei and prominent nucleoli. These tumors are predominantly exophytic
and appear to be less invasive into the muscle bundles than are the
melanocytic and spindle cell type melanomas. |
AM |
Amelanotic Melanoma |
 These
tumors are defined by their gross appearance. Even though they appear
macroscopically as non-pigmented lesions, microscopically they contain
small areas with pigmented cells. They are commonly exophytic. Macroscopically,
they appeared as hypopigmented, obviously exophytic growths that were
bordered by melanistic regions. These neoplasms developed in the X.
helleri x (X. maculatus Jp 163 B x X. helleri) cross,
and arose after MNU treatment. |
Neurological Tumors |
RB |
Retinoblastoma |
 |
Left, Photograph of a fish taken from above showing protrusion of the right eye. Center, Tumor cells invading the inner and outer surface
of the retina, the sclera and the optic nerve. Right, Higher magnification
photomicrograph showing tumor cell histological characteristics. The
arrows delineate the area that shows a rosette-like arrangement. Scale
bars are 200 mm. |
FS |
Fibrosarcoma |
 
 |
Left, Example of a fish developing fibrosarcoma on the base of the caudal fin. Center, Low magnification image of a fibrosarcoma infiltrating muscular structure. Right, Muscle bundles compressed by whorled masses of densely packed spindle cells. |
|
|
SCH |
Schwanoma |
| |
 |
Left, Example of a fish developing fibrosarcoma on the base of the caudal fin. Center, Area of typical palisades. Right, A well circumscribed schwannoma. |
| |
| MPNST | Malignant Peripheral Nerve Sheath Tumor |
 |
Non-tumors |
| |
| MS | Melanosis |
  |
Left, An MNU treated fish with a radially spreading melanosis that is not restricted to the gonopodial region. Right, Cross section of the anterior caudal peduncle showing pronounced melanosis within the integument with a lack of invasiveness. Scale bars are 200 mm. |
Other Tumors |
RC |
Renal Carcinoma |
 |
Contributed by Irma Gimenez-Conti, Steven Kazianis, Rodney Nairn, Don Morizot, and Ron Walter. |
Download printable PDF (Acrobat 4.0) version of this page. |
