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United States Department of Agriculture

Agricultural Research Service

Research Project: Integrated Aquatic Animal Health Strategies

Location: Aquatic Animal Health Research

Title: Pathology in practice: Peripheral nerve sheath tumor in a Shubunkin goldfish

Authors
item Bebak, Julie
item Evans, Joyce
item Weber, E.P. Scott -
item Wolf, Jeffrey -

Submitted to: Journal of the American Veterinary Medical Association
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 4, 2011
Publication Date: April 1, 2012
Repository URL: http://handle.nal.usda.gov/10113/55875
Citation: Bebak, J.A., Evans, J.J., Weber, E., Wolf, J. 2012. Pathology in practice: Peripheral nerve sheath tumor in a Shubunkin goldfish. Journal of the American Veterinary Medical Association. 240(7):827-829.

Interpretive Summary: The peripheral nerve sheath tumors (PNSTs) are skin tumors that have been detected in many fish species, including goldfish, several species of snapper, coho salmon, the bicolor damselfish, and rainbow smelt. They originate cells from cells of the nervous system and generally occur along nerves that are under the surface of the skin. Viruses have been proposed to cause PNSTs, but this has not been confirmed. A benign PNST was identified on an otherwise normal approximately eight-year-old Shubunkin goldfish from an ornamental goldfish pond. The tumor was located on the left side of the fish just below the dorsal fin. It was about one-half inch in diameter, covered by scales and slightly raised above the skin surface. A laboratory investigation that included bacteriological, virological and molecular methods did not find any organisms associated with the tumor. Microscopic examination of the tumor revealed that it had key diagostic features that identified it as a benign PNST. PNSTs can be surgically removed, either by excision or cryosurgery. However, recurrence is more likely after excision than after cryosurgery, hemorrhage is more likely with excision, and freezing allows for more complete removal of tumor cells.

Technical Abstract: Peripheral nerve sheath tumors (PNSTs) have been detected in many fish species, including goldfish, several species of snapper, coho salmon, the bicolor damselfish, and rainbow smelt. They originate from neural crest cells and generally occur along the subcutaneous nerves. A viral etiology has been proposed for these tumors, but has not been confirmed. A benign PNST was identified on an approximately eight-year-old Shubunkin goldfish from an ornamental goldfish pond. The tumor was located on the left side, approximately 1 cm below the cranial end of the dorsal fin. It was covered by scales, was well-circumscribed, 14 mm diameter, and slightly raised above the skin surface. Other than the tumor, the fish was normal, internally and externally. A Gram stain of an impression smear of a cut surface of the nodule was negative for any organisms, as were bacterial cultures, cultures on fish cell lines for virus, and PCR. Upon histologic examination, the key diagnostic feature that identified the mass as a PNST was the proliferation of elongate, spindle-shaped neoplastic cells that were arranged in multi-directional bundles separated by collagenous material in a fibrillar matrix. PNSTs can be surgically removed, either by excision or cryosurgery. However, recurrence is more likely after excision than after cryosurgery, hemorrhage is more likely with excision, and freezing allows for more complete removal of tumor cells.

Last Modified: 8/29/2014
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