JPC SYSTEMIC PATHOLOGY
REPRODUCTIVE SYSTEM
January 2019
R-M03

Signalment (JPC #2033220):  Two-year-old female shih tzu (post partum)

HISTORY:  During a routine spay, the uterine wall was circumferentially and segmentally thickened near the bifurcation.

HISTOPATHOLOGIC DESCRIPTION:  Uterus:  Filling the uterine lumen and expanding the endometrium up to three times normal is a circumferential, irregular, 7 x 10 mm, multilobulated, eosinophilic coagulum that compresses the subjacent endometrium and myometrium, and focally extends into the outer muscular layer of the myometrium.  There is a complex mosaic of coagulative necrosis throughout the coagulum which is admixed with hemorrhage, fibrin, mineral, granular, extracellular bright yellow pigment (hematoidin), and multifocally blood vessels contain poorly organized fibrin thrombin.  Dispersed throughout the base of the coagulum are ectatic, tortuous endometrial glands, and within both the endometrium and subjacent myometrium are dilated, blood-filled sinuses separated by connective tissue and variable numbers of Iymphocytes, plasma cells, neutrophils, and hemosiderin-laden macrophages admixed with large pleomorphic cells (syncytial trophoblasts).  These cells are 30-50 um in diameter, have abundant vacuolated eosinophilic cytoplasm, multiple oval nuclei with clumped chromatin, one distinct nucleolus, and often surround endometrial and myometrial blood vessels. Trophoblasts occasionally contain phagocytized erythrocytes.  Multifocally, ectatic endometrial glands have attenuated epithelium and contain necrotic debris, fibrin, erythrocytes, and scattered neutrophils.  The adjacent endometrial epithelial cells are hypertrophic, with abundant, foamy cytoplasm, vacuoles up to 75 um in diameter (progestational stimulation) and apically located nuclei.  These cells often form focally extensive hyperplastic fronds or papillary projections and palisade along a fibrovascular stroma. Lymphatic vessels within the tunica muscularis are markedly ecstatic (edema) and there is diffuse congestion of uterine blood vessels.

MORPHOLOGIC DIAGNOSIS:  Uterus, placental site:  Necrosis, coagulative, subacute, focally extensive, marked with retention of syncytial trophoblasts, endometrial hyperplasia, hemorrhage and endometritis (subinvolution of placental sites), Shih Tzu, canine.

CAUSE:  Unknown

CONDITION:  Subinvolution of placental sites (SIPS)

GENERAL DISCUSSION:

PATHOGENESIS:

TYPICAL CLINICAL FINDINGS:

TYPICAL GROSS FINDINGS:

TYPICAL LIGHT MICROSCOPIC FINDINGS:

ADDITIONAL DIAGNOSTIC TESTS:

DIFFERENTIAL DIAGNOSIS: 

For histologic findings:

COMPARATIVE PATHOLOGY:

REFERENCES:

  1. Al-Bassam MA, Thomson RG, O'Donnell L. Involution abnormalities in the postpartum uterus of the bitch. Vet Pathol 1981;18:208-218.
  2. Foster, RA. Female reproductive system and mammae. In: Zachary JF, ed. Pathologic Basis of Veterinary Disease. 6th St. Louis, MO: Elsevier; 2017:1189.
  3. Juan-Salles C, Martinez LS, Garner MM. Fatal placental subinvolution in a captive capybara (Hydrochaeris hydrochaeris, order Rodentia). Vet Pathol 2005;42:513-516.
  4. Schlafer DH, Foster RA. Female genital system. In: Maxie MG, ed. Jubb, Kennedy, and Palmers Pathology of Domestic Animals. Vol 3. 6th ed. St. Louis, MO: Elsevier; 2016:440-442.


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