January 2019
R-M08 (NP)

Signalment (JPC #2118235):  2-year-old female Labrador retriever

HISTORY:  This dog presented for routine spay a month after estrus. During surgery a 2.5 cm in diameter, firm, round structure was noted in the left uterine horn just cranial to the bifurcation. On cut section the mucosa was markedly thickened, firm, and hemorrhagic with luminal accumulation of small amounts of flocculent material.

HISTOPATHOLOGIC DESCRIPTION:  Uterus: The endometrium is multifocally expanded up to 8mm by broad-based polypoid projections of endometrium that partially occlude the uterine lumen.  These projections are composed of three distinctive zones. The most superficial zone is composed of long villous folds extending from the endometrial surface, often forming papillary projections, lined by simple columnar to pseudostratified epithelium with foamy, often vacuolated cytoplasm (progestational epithelium) and large vesiculate nuclei, supported by a fibrovascular core.  The superficial aspect of the epithelium is multifocally either eroded or necrotic with accumulation of karyorrhectic debris and fibrin.  There is luminal and intervillous accumulation of an amphophilic to eosinophilic mucoid material.  The middle zone of the polypoid mass is composed of a band of loose fibrous connective tissue that is mildly to moderately expanded by clear space (edema) and lined columnar to cuboidal epithelial cells.  The deepest zone, in contact with the myometrium, is composed of relatively normal uterine stroma surrounding numerous tortuous endometrial glands, dilated up to 400um, lined by attenuated to cuboidal to occasionally hyperplastic epithelial cells, and containing variable amounts of luminal amphophilic to eosinophilic secretory product.  Cystic, hyperplastic endometrial glands multifocally extend into the myometrium (adenomyosis). There are multifocal perivascular lymphoid aggregates within the myometrium.

MORPHOLOGIC DIAGNOSIS:  Uterus, endometrium: Hyperplasia, pseudoplacentational, focally extensive, Labrador retriever, canine (Canis familiaris)

CONDITION SYNONYMS:  Pseudoplacentational endometrial hyperplasia; localized endometrial hyperplasia of pseudopregnancy








Endometrial hyperplasia:  simple (non-cystic) endometrial hyperplasia can be overlooked grossly, cystic endometrial hyperplasia is often grossly noted

Estrogenic plants:  Subterranean clover (Trifolium subterraneum), red clover (Trifolium pretense), alfalfa (Medicago sativa), Medicago truncatula (barrel medic)


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