Approach to endometrial biopsy

Editor's Notes

• #3: Post menopausal endometrium: Inactive endometrial epithelium. Notice the absence of stroma. H&E stain.
• #5: Glandular out pouchings: In complex hyperplasia, the glands are irregular in size and shape with branching and outpouchings. Cytologic atypia is absent. About 3% of such cases progress to adenocarcinoma.
• #6: Isthmic mucosa: may also give the false impression that the endometrium is atrophic or deficient or only from basal region. How to identify the isthmic mucosa? --- uniformly low, relatively avascular mucosa, slit like glands and dense fibrous stroma of small cells. Glandular cytoplasm donot contain mucous substance. Basalis: Glands branch more and supporting stroma around them is more irregular since the collagenous fibers anchoring the basalis to myometrium extend in all directions. Stromal cells in basalis remain refractory to hormones, whereas the stromal cells in isthmic portions may undergo slight cyclical changes.
• #7: Proliferative phase: This phase lasts 2weeks but under physiological conditions may fluctuate between 10 and 20days. Consequently, it’s impossible to determine each of the cycle during proliferative phase. Hence it ‘s divided into Early, Mid and late proliferative phases. Early PP: Sparse glands, narrow. Low columnar. Nuclei-small, oval and dense chromatin. No nucleoli Mid PP: Glands show tortuosity, stratification of epithelium, tall columnar type, dense chromatin, there may be nucleoli, many mitosis. Late PP: regression of edema, mor tortuous glands, pseudostratification of nuclei, nuclei are fusiform.
• #8: AUB=Abnormal uterine bleeding Assessment of response of the EM to hormone Therapy: Estrogen replacement therapy in perimenopausal / post menopausal women and those on Tamoxifen for breast cancer EM is not useful in the diagnosis due to low accuracy.
• #9: *Phillips V, McCluggage WG. Results of a questionnaire regarding criteria for adequacy of endometrial biopsies. J Clin Pathol 2005;58:417–9. If you can make a diagnosis, it is adequate irrespective of the quantity of material in the slide In many cases of postmenopausal bleeding, the patient is not actually postmenopausal but rather is perimenopausal, with a prolonged interval between periods. Before biopsy, many women with abnormal uterine bleeding are already taking exogenous hormones, especially progestogenic compounds, to control the bleeding, and this information is not always conveyed to the pathologist. Other women may be taking hormone replacement therapy or contraceptives. These hormonal compounds may alter the morphological appearance of the endometrium and a knowledge that these, and other relevant drugs such as tamoxifen, are being taken is of paramount importance to the pathologist. The classification of a biopsy specimen as inadequate may have medicolegal and clinical implications. For example, some clinicians routinely conduct a repeat biopsy when an endometrial specimen has been classified as inadequate. The presence of even a minimal amount of endometrial tissue provides presumptive evidence that the endometrial cavity has been entered, although theoretically endometrial-type glands with or without stroma can be derived from tuboendometrial metaplasia or endometriosis within the cervix. It is emphasised that biopsy specimens with scant tissue, which usually comprise only superficial strips of endometrial glands, should be examined carefully under high power to look for mitotic activity (abnormal in truly postmenopausal women) and atypia.
• #10: Post menopausal endometrium: Inactive endometrial epithelium. Notice the absence of stroma. H&E stain.
• #11: The interpretation of the relevance of an unassessable specimen or scant specimen rests with the clinician. As discussed, this is the norm with an atrophic endometrium and no focal lesion on ultrasound scan, but not a reason for repeating the biopsy. With a thickened endometrium, a focal lesion or a strong clinical suspicion of major pathology, however, a scant specimen may be an indication of the need for repeat biopsy.
• #12: AUB=Abnormal uterine bleeding Assessment of response of the EM to hormone Therapy: Estrogen replacement therapy in perimenopausal / post menopausal women and those on Tamoxifen for breast cancer
• #13: AGC=Atypical glandular cells
• #15: Gland in gland appearance: due to squeezing and tearing of curettings and subsequent handling. Artefactual crowding and compression of glands: may result in consideration of a complex endometrial hyperplasia. With this artefact, the glands become moulded together and often there is tearing of the tissue around the glands, which is a clue to the artefactual nature. Pseudopapillary architecture of superficial strips of EM: This may result in consideration of a wide range of papillary lesions, benign and malignant, which occur in the endometrium. Such superficial strips of papillary endometrium, which are generally atrophic, should be examined under high power to look for proliferative activity and nuclear atypia. Crushed endometrial glands and stroma: may be extremely cellular and can cause concern. As with other tissues, crushed areas should not be viewed in isolation.
• #16: Proliferative endometrium with artifactual changes secondary to curettage, which was misinterpreted as endometrial hyperplasia. The glands in this field are neither architecturally irregular nor cystically dilated. The ratio of glands to stroma is about normal for a midproliferative endometrium, and a general orientation of the glands from upper left to upper right is noteworthy.
• #18: Should not be mistaken for hyperplasia
• #19: Papillary fragments: Follow up of both these cases revealed EM cacrinoma. In such cases look for proliferative activity (mitosis)
• #22: PP: Caution should be exercised in diagnosing a proliferative endometrium in the absence of mitoses, although these may be few in number. Stromal and glandular mitoses are commonly found in a proliferative endometrium. ~cf: atrophic endometrium: it may resemble porliferative enodmetrium as the glands are tubular and may exhibit nuclear stratification.
• #25: ESP
• #26: The presence of plasma cells is widely regarded as the most useful criterion for a diagnosis of endometritis, although these are often admixed with other inflammatory cells, both acute and chronic, and may be a minor component of the inflammatory cell infiltrate. In endometritis, the inflammatory cell infiltrate may be focal and plasma cells just beneath the surface glands are usually most easily identified. It is emphasised that in the absence of the other morphological features of endometritis described earlier, an exhaustive search for plasma cells is not justified. Occasional stromal plasma cells may be identified in an otherwise normal endometrium, and in these circumstances a diagnosis of endometritis should not be made. Plasma cells may be present in the stroma of endometrial polyps and also in association with an endometrial malignancy. Other morphological features that alert the pathologist to a possible endometritis: an endometrium that exhibits a disturbance in maturation—for example, focal areas that are out of cycle with other areas Stromal edema and, characteristically, a spindle-cell alteration of the stroma, especially around glands A degree of architectural complexity and cytological atypia may also be seen if the inflammatory cell infiltrate is marked In the absence of the other morphological features of endometritis described earlier, an exhaustive search for plasma cells is not justified
• #27: Lymphoid aggregate in proliferative endometrium is a normal finding, not endometritis.
• #28: Endometritis: a spindle-cell alteration of the stroma, especially around glands and presence of plasma cells. Plasma cell markers: VS38 (CD38) and syndecan (CD138) have also been used to identify plasma cells,9–11 although in my experience endometrial glandular and stromal cells are diffusely positive with VS38 (fig 6), making identification of plasma cells impossible. By contrast, syndecan is more useful, as most stromal cells are negative, although endometrial glands are positive.
• #30: A variant of endometritis, termed ‘‘focal necrotising endometritis’’, has been described and is characterised by an inflammatory cell infiltrate comprising lymphocytes, neutrophils and histiocytes without plasma cells. Granulomatous endometritis raises the possibility of sarcoidosis, tuberculosis and other granulomatous diseases.
• #31: The pathological diagnosis is generally straightforward if the gynaecologist is aware of the presence of a polyp, has conveyed this information to the pathologist and has removed the polyp intact. The gynaecologist may believe that a polyp is present, but histological examination shows a cyclical endometrium, often secretory in type, reflecting the fact that an abundant secretory endometrium may have a polypoid appearance. Often, the gynaecologist is not aware of the presence of a polyp. In such instances, fragments of polyp are often admixed with fragments of non-polypoid endometrium, making the diagnosis difficult, as the features can be subtle. When a biopsy is carried out for abnormal uterine bleeding, the pathologist should always consider the possibility of a polyp. On examination under low power, the initial clue to the presence of a polyp is often the admixture of fragments of a normal cyclical endometrium and fragments that are morphologically different.17 The stroma is generally more fibrous than in the surrounding endometrium, although this is not invariable. Other morphological features commonly found in polyps include collections of thick-walled stromal blood vessels, glandular architectural abnormality (often in the form of dilated glands with unusual shapes and focal crowding) and various epithelial metaplasias. The glands within a polyp often show proliferative activity, even when the surrounding endometrium does not.
• #32: A diagnosis of simple hyperplasia should not be made in the case of an endometrial polyp, as a glandular architecture reminiscent of simple hyperplasia is a normal feature within a polyp. As discussed earlier, the histological features of any non-polypoid endometrium represented should be described and, if none is present, this should be mentioned. Carcinomas, so-called ‘‘polyp cancers’’, may arise in endometrial polyps. Obviously, if a cancer is identified in an endometrial polyp removed by biopsy, it is impossible to ascertain, without full evaluation of the surrounding endometrium, whether the cancer has arisen in or has secondarily involved the polyp. Polyp cancers may be endometrioid in type, but serous proliferations, serous carcinoma or its precursor lesion endometrial intraepithelial carcinoma (EIC), have a particular propensity to arise in or be associated with otherwise benign endometrial polyps.
• #34: Ciliated cells are common in a normal cyclical endometrium. I would reserve a diagnosis of ciliated metaplasia for cases characterised by extensive ciliation and where the cells have abundant eosinophilic cytoplasm, resulting in an appearance similar to the epithelium of the normal fallopian tube. Ciliated cells are normal in the lower uterine segment and should not be interpreted as ciliated metaplasia. Papillary syncytial metaplasia, although termed metaplasia, is actually a reparative response occurring after breakdown22 (fig 9). When florid, this may be suggestive of a serous carcinoma or an EIC. In this circumstance, attention should be paid to the background endometrium, which, in papillary syncytial metaplasia, usually shows features of breakdown. In problematic cases, p53 immunohistochemistry (discussed below) may be of value. With florid mucinous metaplasia, exclusion of a welldifferentiated mucinous adenocarcinoma can be extremely difficult, if not impossible, on endometrial biopsy, as some mucinous adenocarcinomas of the endometrium are cytologically bland, even those which show myometrial infiltration. Mucinous proliferations of the endometrium, which are identified on biopsy, can be subdivided into categories based on the degree of architectural complexity, which correspond to an increasing risk of the presence of mucinous adenocarcinoma in subsequent hysterectomy. With some epithelial metaplasias—for example, clearcell metaplasia, papillary syncytial metaplasia and benign papillary proliferation—the differential diagnosis may be between a metaplastic process and a type-2 endometrial cancer or an EIC. In such instances, immunohistochemical analysis may be of value, in that EIC and type-2 cancers usually show diffuse intense nuclear p53 staining, whereas oestrogen receptor is generally negative or weakly positive. By contrast, most metaplastic processes are oestrogen receptor positive and exhibit a weak heterogeneous pattern of p53 staining.25 Many exceptions exist, however, with some clear-cell carcinomas in particular being p53 negative or weakly positive. Endometrial intraepithelial carcinoma (EIC): serous carcinoma or its precursor lesion
• #40: Endometrial stromal nodule with smooth muscle metaplasia as seen in the center and right (a, H and E stain, ×200) and as seen on low power with a smooth interface with normal myometrium (H and E stain, ×40)
• #41: Endometrial stromal nodule with smooth muscle metaplasia as seen in the center and right (a, H and E stain, ×200) and as seen on low power with a smooth interface with normal myometrium (H and E stain, ×40)
• #42: Although the efficacy of tamoxifen in breast cancer is due to its anti-oestrogenic properties, tamoxifen may exert a proliferative effect on the endometrium.
• #43: One of the most common lesions to be misdiagnosed as a hyperplasia is an endometrial polyp, especially when this is removed piecemeal. In general, secretory activity is rare in endometrial hyperplasias, although this does occur, especially when hormone treatment has already been instigated. ---------------- The 1994 WHO classification results in four categories of endometrial hyperplasia—simple non-atypical, complex non-atypical, simple atypical and complex atypical. In practice, atypia usually occurs in endometria with complex architecture and it is uncommon to diagnose simple atypical hyperplasia, although this rarely occurs. As a result, many pathologists use three categories of endometrial hyperplasia—simple, complex and atypical. All these categories have an increased risk of developing an endometrioid-type endometrial adenocarcinoma, although this is extremely low in simple and complex endometrial hyperplasias (approximately 1% and 3%, respectively),50 which are usually self-limiting lesions that regress; although once the lesions are diagnosed, hormonal treatment is usually instigated. The risk of developing an endometrioid adenocarcinoma after a diagnosis of atypical hyperplasia is difficult to ascertain, as, once atypical endometrial hyperplasia is diagnosed, it is treated either hormonally or more usually surgically. With atypical hyperplasia, however, there is a considerable risk of transformation into an endometrioid adenocarcinoma, probably of the order of 25–40%. Additionally, an endometrioid adenocarcinoma may already be present and not sampled by biopsy. In my experience, many cases diagnosed as atypical endometrial hyperplasias represent well-differentiated endometrioid adenocarcinoma. In complex hyperplasia, there is an increase in the gland to stroma ratio with glandular crowding. The glands are often closely packed, although some stroma usually remains between individual glands. The glands show proliferative activity and, by definition, there is no nuclear atypia. In atypical hyperplasia, there is, by definition, nuclear atypia. Assessing nuclear atypia is one of the most subjective and problematic areas in gynaecological pathology, but this assessment is crucial in the management of endometrial hyperplasia, as surgery is generally undertaken for atypical hyperplasia, whereas hormone treatment is common for nonatypical hyperplasia, although there are many exceptions. Nuclear atypia may be subtle and in its evaluation it is useful to compare the cytology of the atypical glands with that of the residual normal endometrial glands (fig 12). In atypical hyperplasia, the nuclear changes are often accompanied by cytoplasmic changes, such that the cells have more abundant, often eosinophilic, cytoplasm. Cytoplasmic changes, including increased cytoplasmic eosinophilia, may also be seen in various endometrial metaplasias, such as ciliated metaplasia. Nuclear features in atypical hyperplasia, which, as stated earlier, are often subtle, include nuclear stratification, loss of polarity, nuclear rounding and the presence of nucleoli. In fact, rather than overt nuclear atypia, it is often the differing nuclear features between abnormal and normal glands that is characteristic.
• #44: Many of the genetic changes typical for endometrioid endometrial cancer are present, including: micro satellite instability; PAX2inactivation; mutation of PTEN, KRAS andCTNNB1 (β-catenin)
• #45: EM hyperplasia
• #46: Endometrial hyperplasia is defined as endometrial proliferation with an increase in gland to stroma ratio (from 2:1 to 3:1). It is divided into Simple hyperplasia (with or without atypia) and Complex hyperplasia (with or without atypia) according to the WHO Classification. The image shows a proliferation of dilated endometrial glands with no or minimal outpouchings. It is an example of simple hyperplasia without atypia. Progression to adenocarcinoma occurs only in about 1% of cases. Endometrial hyperplasia is the result of excessive estrogenic stimulation of the endometrium. Associated conditions include obesity, polycystic ovary disease (including Stein-Leventhal syndrome), functioning granulosa cell tumors of ovary, and exogenous estrogens etc.
• #47: Glandular out pouchings: In complex hyperplasia, the glands are irregular in size and shape with branching and outpouchings. Cytologic atypia is absent. About 3% of such cases progress to adenocarcinoma.
• #48: Complex Endometrial Hyperplasia without AtypiaComments:In complex hyperplasia, the glands are irregular in size and shape with branching and outpouchings. Cytologic atypia is absent. About 3% of such cases progress to adenocarcinoma.
• #52: Complex hyperplasia without nuclear atypia – notice the intervening stroma Endometrial endometrioid carcinoma. Notice the back to back glandular proliferation with little intervening stroma.
• #55: In a simple hyperplasia, the normal gland to stroma ratio is maintained or there is slight increase. The endometrium shows proliferative activity, with cystically dilated glands of irregular sizes and shapes. Some glands may exhibit ‘‘outpouchings’’, ‘‘infoldings’’ and ‘‘budding’’. No nuclear atypia is seen, the nuclei being oval and maintaining their orientation to the underlying basement membrane. A major problem is the distinction between simple endometrial hyperplasia and disordered proliferative endometrium, a term widely used, although the histological features are not well characterised. The morphological features of these overlap and the distinction is poorly reproducible. In my practice, I require to see large numbers of dilated glands to diagnose simple hyperplasia, whereas if only occasional dilated glands are present, I diagnose this as disordered proliferative endometrium, especially if the patient is perimenopausal.
• #56: AR=Androgen receptor Immunohistochemical staining of FOXA1 and AR in normal endometrium, atypical hyperplasias, and endometrial cancer. FOXA1 and AR expression in normal endometrium, atypical hyperplasias and endometrial cancer. (Immunohistochemical staining, ×200) We assessed relative FOXA1 and AR levels in EC samples, atypical hyperplasias, and normal endometrial tissue samples using immunohistochemistry. FOXA1 was higher in atypical hyperplasias and even higher in EC compared with normal endometrial tissues (p = 0.005) (Figure 1, Additional file 1: Table S1). Notably, the expression of AR was also significantly higher in EC (p = 0.033) (Figure 1, Additional file 2: Table S2). The results also showed that FOXA1 expression correlated positively with AR expression (p = 0.003) (Table 2). Correlation analysis between FOXA1 and pathological grade of EC showed that FOXA1 expression was higher in G3 tumors (6/6) compared with either G2 (17/22) or G1 (19/35) tumors (p = 0.038) (Table 1). Significantly higher FOXA1 expression was also found in tumors that displayed a greater depth of myometrial invasion (p = 0.035). Finally, our results also indicated that AR was much higher in G3 and G2 tumors compared to G1 (p = 0.040) (Table 1). These results suggested that FOXA1 expression, which correlated with AR expression, had a connection with the development of EC and risk-associated clinical features of the disease.
• #57: Figure 1. Endometrium with normal surface epithelium. A, Hematoxylin-eosin, original magnification ×400. B, Cyclin D1 immunohistochemistry showing strong reactivity in approximately 30% of epithelial nuclei (original magnification ×400). Figure 2. Endometrium with complex hyperplasia. A, Hematoxylin-eosin, original magnification ×100. B, Cyclin D1 immunohistochemistry showing strong reactivity in approximately 90% of nuclei in glands with hyperplasia (original magnification ×100). Figure 3. Endometrioid adenocarcinoma and adenomyosis. Cyclin D1 overexpression in approximately 90% of nuclei in neoplastic glands and no staining in adenomyosis glands. A, Hematoxylin-eosin, original magnification ×100. B, Cyclin D1 immunohistochemistry, original magnification ×100
• #60: In this pretherapy curettage specimen, only rare neoplastic cells (center) were seen in voluminous necrotic debris; better microscopic evidence must be sought before making a definitive diagnosis of carcinoma.
• #61: Several features assist in distinguishing between atypical hyperplasia and grade-1 endometrioid adenocarcinoma. A desmoplastic stromal response is strong supportive evidence of an adenocarcinoma,57 58 but this is identified only in a minority of biopsies of endometrial carcinoma. A solid backto-back glandular architecture with complete exclusion of stroma is suggestive of adenocarcinoma, as in most atypical hyperplasias a little stroma remains between glands. Bridging between adjacent glands, resulting in a cribriform pattern, as well as the presence of luminal necrosis with polymorph infiltration, suggests an adenocarcinoma. A surface papillary pattern, maze-like meandering glands and solid non-squamoid areas also suggest an adenocarcinoma. As stated earlier, however, atypical hyperplasia and grade-1 endometrioid adenocarcinoma form part of a spectrum without sharp demarcation.
• #62: Finding fat in EM curetting is a critical value. It should be intimated to the clinician: may be uterine perforation.