JPC SYSTEMIC PATHOLOGY
REPRODUCTIVE SYSTEM
January 2019
R-N10

Signalment (JPC #2026123):  A cat

HISTORY:  This cat had diffusely swollen and enlarged mammary glands along the entire mammary chain.

HISTOPATHOLOGIC DESCRIPTION:  Mammary gland:  Diffusely, the mammary gland is expanded by variably sized lobules composed of hyperplastic ducts surrounded by multiple layers of myofibroblasts imbedded within an loose stroma that blends into dense bands of collagenous stroma.  Ducts are lined by 1-3 layers of cuboidal to columnar epithelial cells.  The surrounding spindle cells (myoepithelial cells) have indistinct cell borders, a scant amount of eosinophilic fibrillar cytoplasm, an oval nucleus with finely stippled chromatin, and 1-2 nucleoli.  Multifocally ducts are filled with small amounts of necrotic debris, sloughed epithelial cells, and few neutrophils.  Within the periductal stroma there are moderate numbers of foamy macrophages and fewer lymphocytes and plasma cells.  Diffusely the superficial dermis is mildly expanded by increased clear space and ectatic lymphatics (edema).  The epidermis is mildly hyperkeratotic.

MORPHOLOGIC DIAGNOSIS:  1. Mammary gland:  Hyperplasia, fibroepithelial, diffuse, moderate, breed unspecified cat, feline.

CAUSE:  Prolonged elevated levels of progesterone

CONDITION:  Mammary fibroadenomatous hyperplasia

SYNONYMS:  Fibroepithelial hyperplasia, feline mammary hypertrophy

GENERAL DISCUSSION: 

PATHOGENESIS:

The mechanism for progesterone induced hyperplasia involves IGF-1 and growth hormone

TYPICAL CLINICAL FINDINGS:

TYPICAL GROSS FINDINGS:

TYPICAL LIGHT MICROSCOPIC FINDINGS:

DIFFERENTIAL DIAGNOSIS:

COMPARATIVE PATHOLOGY:

REFERENCES:

  1. Barthold SW, Griffey SM, Percy DH. Pathology of laboratory rodents and rabbits. 4th ed. Ames, IA: John Wiley & Sons, Inc.; 2016:164-166.
  2. Foster RA. Female reproductive system and mammae. In: Zachary JF, ed. Pathologic Basis of Veterinary Disease. 6th ed. St. Louis, MO: Elsevier; 2017:1193.
  3. Goldschmidt MH, Pena L, Zappulli V. Tumors of the mammary gland. In: Meuten DJ, ed. Tumors in domestic animals. 5th ed. Ames, IA: John Wiley & Sons, Inc.; 2017:758.
  4. Krimer PM, Harvey SB, Blas-Machado U, Lauderdale JD, Moore PA. Reversible fibroadenomatous mammary hyperplasia in male and female New Zealand white rabbits associated with cyclosporine A administration. Vet Pathol. 2009;46:1144-1148.
  5. de Sant’Ana FJF, Carvalho FC et al. Mammary diffuse fibroadenomatoid hyperplasia in water buffalo (Bubalus bubalis): three cases. J Vet Diagn Invest. 2014 May 12;26(3): 453-456.
  6. Schlafer DH, Foster RA. Female genital system. In: Maxie MG, ed. Pathology of Domestic Animals. Vol 3. 6th ed. St. Louis, MO: Elsevier; 2016:460-461.


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