JPC SYSTEMIC PATHOLOGY
ENDOCRINE SYSTEM
February 2019
E-N05

Signalment (JPC #2237078):  A rat.

HISTORY:  None

HISTOPATHOLOGIC DESCRIPTION:  Thyroid gland:  Expanding and effacing 90% of thyroid parenchyma is a partially encapsulated, multilobulated, moderately cellular, infiltrative neoplasm composed of polygonal cells arranged in variably sized, distinct nests and islands surrounded by thin fibrous septa.  Neoplastic cells have variably distinct cell borders with a moderate amount of pale eosinophilic granular cytoplasm and often palisade along the stroma.  Nuclei are round to oval with finely stippled chromatin and indistinct nucleolus.  The mitotic rate is < 1 per 10 HPF.  Multifocally, there is single cell necrosis, hemorrhage within the nests of neoplastic cells and within the capsule and septa, there are few mast cells and hemosiderin-laden macrophages.  Neoplastic cells are multifocally separated and surrounded by abundant, extracellular amorphous eosinophilic material (amyloid or sclerotic collagen). Few remaining intact follicles are variably ectatic, lined by attenuated epithelial cells, and filled with abundant eosinophilic secretory product (colloid).

MORPHOLOGIC DIAGNOSIS:  Thyroid gland:  C-cell carcinoma, strain not specified, rat, rodent.

SYNONYMS:  Medullary thyroid carcinoma; ultimobranchial tumor; parafollicular cell thyroid carcinoma

GENERAL DISCUSSION:

PATHOGENESIS:

TYPICAL CLINICAL FINDINGS:

TYPICAL GROSS FINDINGS:

TYPICAL LIGHT MICROSCOPIC FINDINGS:

ADDITIONAL DIAGNOSTIC TESTS:

ULTRASTRUCTURE:

DIFFERENTIAL DIAGNOSIS:

COMPARATIVE PATHOLOGY:

REFERENCES:

  1. DeCock HE, MacLachlan NJ. Simultaneous occurrence of multiple neoplasms and hyperplasias in the adrenal and thyroid gland of the horse resembling multiple endocrine neoplasia syndrome: case report and retrospective identification of additional cases. Vet Pathol. 1999;36(6):633-636.
  2. Fox JG, Dangler CA, Synder SB, Richard MJ, Thilsted JP. C-cell carcinoma (medullary thyroid carcinoma) associated with multiple endocrine neoplasms in a ferret (Mustela putorius). Vet Pathol. 2000;37(3):278-282.
  3. Hirayama K, Kagawa Y, Nihtani K, Taniyama H. Thyroid c-cell carcinoma with amyloid in a red fox (Vulpes vulpes schrenchki). Vet Pathol. 1999;36(4):342-344.
  4. Mense MG, Boorman GA. Thyroid gland. In: Suttie AW, Leininger JR, Bradley AE, eds. Boorman’s Pathology of the Rat. 2nd ed. San Diego, CA: Elsevier; 2018:681-683.
  5. Miller MA. Endocrine system. In: McGavin MD, Zachary JF, eds. Pathologic Basis of Veterinary Disease. 6th ed. St. Louis, MO: Elsevier; 2017:702.
  6. Patnaik AK, Lieberman PH. Gross, histologic, cytochemical, and immunocytochemical study of medullary thyroid carcinoma in sixteen dogs. Vet Pathol. 1991;28(3):223-233.
  7. Pope JP, Steeil J, Ramsay EC, Reel D, Newman SJ. Spontaneous proliferative and neoplastic lesions in thyroid and parathyroid glands of nondomestic felids. J Vet Diagn Invest. 2017; 29(1):8-13.
  8. Ramos-Vara JA, Frank CB, DuSold D, Miller MA. Immunohistochemical detection of Pax8 and Napsin A in canine thyroid tumours: Comparison with thyroglobulin, calcitonin and thyroid transcription factor 1. J Comp Pathol. 2016; 155(4):286-298.
  9. Rosol TJ, Grone A. Endocrine glands. In: Maxie MG, ed. Jubb, Kennedy and Palmer’s Pathology of Domestic Animals. Vol 3. 6th St. Louis, MO: Elsevier; 2015:333-336.
  10. Rosol TJ, Meuten DJ. Tumors of the endocrine glands. In: Meuten DJ, ed. Tumors in Domestic Animals. 5th ed. Ames, IA: John Wiley & Sons, Inc.; 2017:776, 803-809, 812.


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