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PROPOSED DIAGNOSTIC CRITERIA FOR PROLIFERATIVE THYROID LESIONS IN BONY FISHES
Citation:
Fournie, J W., W. E. Hawkins, M. J. Wolfe, AND J. Wolf. PROPOSED DIAGNOSTIC CRITERIA FOR PROLIFERATIVE THYROID LESIONS IN BONY FISHES. Presented at International Symposium on Aquatic Animal Health, New Orleans, LA, Sep 1-5, 2002.
Description:
Distinguishing hyperplastic lesions from neoplasia in the thyroid of bony fishes has been debated by scientists for about one hundred years. As early as the first decade of the last century, the histological interpretation of some of the striking proliferative lesions observed in the thyroid of a number of species has been controversial. The confusion is partly due to the fact that thyroid tissue in bony fishes is unencapsulated, is capable of widespread ectopic growth in many species, and is frequently predisposed to extensive hyperplastic proliferation. Suggested factors that may cause proliferation of fish thyroid include iodine deficiency, poor water quality, genetics, abnormal nutrition, and seasonal factors. In some cases, the resulting
hyperplasia can be extensive and has been reported to infiltrate and destroy normal tissues (e.g., Lake Erie coho salmon). In order to make the diagnosis of proliferative thyroid lesions in fishes simpler and to end the continuing controversy, we propose specific criteria for distinguishing hyperplastic from neoplastic lesions in teleosts. The primary lesion categories are follicular cell hyperplasia, adenoma, and carcinoma. Specific diagnostic criteria will be provided for these categories as well as any required sub-categories. For example, follicular cell hyperplasia may be focal, nodular, or ectopic. Illustrated examples of each type of proliferative
lesion will be presented to demonstrate the key diagnostic features of each lesion type.