Endometrial polyps Dr Shaun Monagle MBBS 1991

Definition Benign localised overgrowth of endometrial glands and stroma, covered by epithelium, projecting above the adjacent epithelium Clonal lesions chromosome 6

Clinical features Prevalence ~ 24% More common in women > 40 Present with intermenstrual or post-menopausal bleeding Infertility Persistent bleeding following curettage Common association with Tamoxifen use

Pathological findings Sessile or pedunculated Size: 1mm and beyond – may fill the endometrial cavity and project through the cervical os May be multiple May originate anywhere, but most commonly fundus

polyp

Histopathology Irregularly outlined glands that may be out of phase with endometrium Fibrovascular stalk or fibrous stroma with numerous thick walled vessels Metaplastic epithelium particularly squamous may be present Those in the lower uterine segment may contain endocervical glands Mesenchymal component contains endometrial stroma, fibrous tissue or smooth muscle. Absence of cytological atypia hyperplasia, carcinoma (any type) and carcinosarcoma may involve or be entirely confined to a polyp endometrial intraepithelial carcinoma may be identified in an atrophic polyp

Benign polyp in a hysterectomy specimen Note Endometrial epithelium on three surfaces Dilated glands Fibrotic stroma Scattered dilated thick walled blood vessels

Endometrial polyp Note: Dilated thick-walled blood vessels Stromal fibrosis (less than previous image) Proliferative endometrial glands

Endometrial polyp (low power) features cystically dilated glands of various sizes and shapes

Endometrial polyp (high power) characteristic features of thick walled blood vessels in a fibrous core

Classification Morphologically diverse lesions that are difficult to subclassify. Most are either hyperplastic, atrophic or functional. Hyperplastic resemble diffuse non polypoid endometrial hyperplasia no evidence that these have the same significance as diffuse hyperplasia, so best to avoid the term hyperplastic in the diagnosis Atrophic low columnar or cuboidal cells lining cystically dilated glands typically in post-menopausal patients Functional resemble normal cycling endometrium relatively uncommon

Tamoxifen related polyps Larger, sessile with a honeycomb appearance bizarre stellate shape of glands and frequent epithelial and stromal metaplasias often periglandular stromal condensation malignant transformation in up to 3% interestingly the cytogenetic profile is similar to non-iatrogenic lesions

Differential Diagnosis Endometrial hyperplasia diffuse process, majority of fragments in curettage, absence of thick walled vessels polypoid endometrial carcinoma malignant epithelial cells adenofibroma adenosarcoma stromal cells cytologically atypical and mitotically active stromal cells packed tightly around non malignant glands leaf like pattern

Adenosarcoma

Adenosarcoma note the cellular stroma

Adenosarcoma stromal cells condensing around cytologically benign glands

Clinical behavior and treatment At most 5% of polyps contain carcinoma polyps may represent a marker of increased cancer risk, but no evidence suggests they are more likely to become cancer than the adjacent endometium those containing atypical hyperplasia or carcinoma should be treated as per similar flat lesions

References http://www.pathologyoutlines.com Blaustein’s Pathology of the Female Genital Tract. 5th Edition. RJ Kurman. Springer-Verlag New York. 2002. Differential Diagnosis in Surgical Pathology. Haber, Gattuso, Spitz and David. Saunders, 2002 WHO Classification of Tumour. Pathology and Genetics. Tumours of the breast and female genital organs. Tavassoli and Devilee. IARC Press, 2003 Sternberg’s Diagnostic Surgical Pathology, 4th edition. SE Mills. Lippincott, Williams and Wilkins, 2004