Symposium part IV: investigative approaches to endocervical pathology

Application of immunohistochemistry to gynecologic pathology

CONTEXT

A large variety of tumors and lesions arise in the female genital tract. Although the majority of these can be correctly recognized on routine hematoxylin-eosin-stained slides, occasional cases present a diagnostic challenge. Immunohistochemical stains are extremely useful in resolving many of these problematic cases. As the knowledge in this area is constantly expanding, it is useful to have this updated information in a review form for easy access.

OBJECTIVE

To present our current knowledge of immunohistochemistry of the lesions of the female genital tract in a readily accessible form.

DATA SOURCES

The review is based on previously published articles on this topic.

CONCLUSIONS

Immunohistochemical stains help in reaching a conclusive diagnosis in a variety of problematic lesions seen in gynecologic pathology. As in any other system, immunohistochemical findings need to be interpreted in light of the clinical history and morphologic findings.

Primary endometrioid adenocarcinoma of the cervix with widespread squamous metaplasia--a potential diagnostic pitfall

BACKGROUND

Uterine or endocervical biopsies that contain endometrioid adenocarcinoma with widespread squamous metaplasia are usually of endometrial origin. The presence of squamous metaplasia is said to be helpful in distinguishing endocervical from endometrial adenocarcinomas in small biopsy samples.

CASE PRESENTATION

A 51-year-old woman presented with post-coital and post-menopausal bleeding. Biopsy of a friable lesion in the proximal endocervical canal revealed an endocervical adenocarcinoma of endometrioid type with widespread squamous metaplasia. The latter feature initially raised the possible diagnosis of a primary endometrial adenocarcinoma. However, immunohistochemical marker studies indicated a diagnosis of primary endocervical adenocarcinoma of endometrioid type and this was confirmed at hysterectomy.

CONCLUSION

Squamous differentiation is not well documented in endocervical adenocarcinomas of endometrioid type and, when widespread, may represent a diagnostic pitfall for pathologists. Interpretation of small biopsies from the endocervical canal on the basis of morphology alone may lead to misdiagnosis and inappropriate surgical management.

Immunohistochemistry as a diagnostic aid in cervical pathology

As with biopsies from other sites in the female genital tract, immunohistochemistry is now being increasingly used in cervical pathology as an aid to diagnosis. In this review, I discuss applications of immunohistochemistry in diagnostic cervical pathology with a particular focus on recent developments. It is emphasised that immunohistochemistry is to be used as an adjunct to routine morphological examination and that no marker is totally specific or sensitive for a given lesion. Although much of this review focuses on glandular lesions, the value of markers, such as MIB1 and p16, in the assessment of pre-invasive cervical squamous lesions is discussed. In the broad field of cervical glandular lesions, topics covered include: the value of markers such as MIB1, p16 and bcl-2 in distinguishing adenocarcinoma in situ and glandular dysplasia from benign mimics; markers of mesonephric lesions, including CD10; markers of value in the diagnosis of minimal deviation adenocarcinoma, such as HIK1083; markers of value in distinguishing metastatic cervical adenocarcinoma in the ovary from primary ovarian endometrioid or mucinous adenocarcinoma. Rarely ectopic prostatic tissue occurs in the cervix, which can be confirmed by positive staining with prostatic markers. A panel of markers, comprising oestrogen receptor, vimentin, monoclonal carcinoembryonic antigen and p16, is of value in distinguishing between a cervical adenocarcinoma and an endometrial adenocarcinoma of endometrioid type. Markers of use in the diagnosis of cervical neuroendocrine neoplasms, including small cell and large cell neuroendocrine carcinoma, are discussed. It is stressed that small cell neuroendocrine carcinomas may be negative with most of the commonly used neuroendocrine markers and this does not preclude the diagnosis. p63, a useful marker of squamous neoplasms within the cervix, is of value in distinguishing small cell neuroendocrine carcinoma (p63 negative) from small cell squamous carcinoma (p63 positive) and in confirming that a poorly differentiated carcinoma is squamous in type.

Mucinous expression in benign and neoplastic glandular lesions of the uterine cervix

CONTEXT

Mucins are glycoproteins produced by both normal and neoplastic glandular epithelial cells including endocervix.

OBJECTIVE

To determine the expression of mucins in uterine cervical glandular lesions and whether mucin expression correlates with the nature and origin of the glandular lesions.

DESIGN

Antibodies to MUC1, MUC2, MUC4, and MUC5AC were applied on 52 cases including 14 endocervical adenocarcinomas (including 4 adenosquamous carcinomas), 9 endometrial carcinomas (8 endometrioid adenocarcinomas and 1 adenosquamous carcinoma), 8 adenocarcinoma in situ (AIS), 2 glandular dysplasias, 6 tubal metaplasias, 10 microglandular hyperplasias, and 3 normal endocervix. The presence of any staining was considered positive.

RESULTS

All benign endocervical epithelia, including tubal metaplasia and microglandular hyperplasia, expressed MUC1, MUC4, and MUC5AC but not MUC2. Almost all endocervical AIS and carcinomas and all endometrial adenocarcinomas expressed MUC1; the exceptions were 2 cases of endocervical adenocarcinoma and 1 case of adenosquamous carcinoma of the endocervix. MUC2 staining was noted in 25%, 40%, and 22% of AIS, endocervical adenocarcinomas, and endometrial adenocarcinomas, respectively. About 38% of AIS, 75% of endocervical adenocarcinomas, and 44% of endometrial adenocarcinomas expressed MUC4. Half of AIS, most of endocervical adenocarcinomas, and 22% of endometrial adenocarcinomas expressed MUC5AC. The difference in MUC4 and MUC5AC expression between benign endocervical lesions and AIS and the difference in MUC5AC expression between endocervical and endometrial neoplasms were statistically significant.

CONCLUSIONS

Mucin expressions differed among benign endocervical lesions and AIS and among endocervical and endometrial malignancies. These results suggest that mucin staining may potentially be helpful in differentiating various uterine cervical glandular lesions.

The significance of prohibitin and c-Met/hepatocyte growth factor receptor in the progression of cervical adenocarcinoma

To examine the importance of prohibitin 1 and c-Met/hepatocyte growth factor receptor (HGFR) expression in human cervical adenocarcinomas, 85 patients (69 with invasive adenocarcinoma [ACA] and 16 with adenocarcinoma in situ [AIS]) were studied using immunohistochemistry. High prohibitin 1 expression was found in 51 (73.9%) of the 69 ACAs and 11 (68.7%) of the 16 AIS lesions. Prohibitin 1 overexpression was significantly higher in ACA and AIS than in adjacent nonneoplastic glandular epithelium (P < .001 for both comparisons). Prohibitin 1 expression was also positively related to tumor size (P = .019) or parametrial involvement (P = .027) in ACA. c-Met was expressed in 21 ACAs (30.4%) and was positively correlated with the Fédération Internationale de Gynécologie et d'Obstétrique (International Federation of Gynecology and Obstetrics) stage classification (P = .007) or nodal metastasis (P = .047). Nodal metastasis (P = .028) and c-Met expression (P = .022) were independent predictors for the overall survival of patients in multivariate analysis using the Cox regression method. Prohibitin 1 activation seems to be an early event, whereas c-Met overexpression may be important for the progression of cervical adenocarcinomas. Evaluation of c-Met expression status may identify a subset of patients with cervical adenocarcinoma who require more intensive treatment.

Apoptosis, Proliferation, and Expression of p53 and bcl-2 in Endocervical Glandular Intraepithelial Lesions and Invasive Endocervical Adenocarcinoma

We evaluated apoptosis, proliferation, and p53 and bcl-2 expression in a spectrum of intraepithelial and invasive endocervical glandular lesions currently recognized by the World Health Organization as adenocarcinoma in situ, lesions with atypia "less than adenocarcinoma in situ" (endocervical glandular dysplasia and endocervical glandular atypia), and invasive adenocarcinoma. Aside from nuclear atypia, increased mitotic activity and apoptosis are consistent and closely correlated morphologic features of endocervical adenocarcinoma in situ. Apoptotic bodies and mitotic figures were counted in 32 examples of normal endocervical glands, 35 of endocervical glandular atypia, 30 of endocervical glandular dysplasia, 34 of adenocarcinoma in situ, and 30 of invasive adenocarcinoma. These results were correlated with immunohistochemical staining for MIB1, bcl-2, and p53 performed on 20 examples of each. Mitotic counts, p53 expression, and bcl-2 expression all increased significantly and in proportion to the degree of atypia in the spectrum of endocervical lesions. Apoptotic body counts and MIB1 expression also increased significantly with increasing atypia, but showed higher levels in adenocarcinoma in situ than in invasive adenocarcinoma. Apoptosis correlates with proliferation as measured by mitotic counts and MIB1, and also with p53 and bcl-2 expression. Apoptosis appears to be an important mechanism in the pathogenesis of endocervical glandular lesions and may be useful as an aid in their evaluation and diagnosis.

Mucin Expression in Nonneoplastic and Neoplastic Glandular Epithelia of the Uterine Cervix

Although it is well known that the uterine cervix contains mucin-producing glandular epithelium, only a few studies have described the changes in mucin that accompany malignant transformation. In this study the authors evaluated the characteristics of mucin expression in the normal endocervical epithelium and mucinous and endometrioid adenocarcinomas of the uterine cervix. The normal endocervical epithelium was characterized by predominant sulfomucin and MUC1 expression in all sites and MUC5AC expression in the surface epithelium, while MUC2 was not detected at all and pyloric gland type mucin (using antibody HIK1083) was detected in less than 1% of cases. Cervical adenocarcinomas, especially mucinous adenocarcinomas, showed marked variability in mucin expression that included mucins of pyloric gland and intestinal type.

Pathology of Cervical Cancer

Squamous cell carcinoma is the most common malignant cervical tumor, but the incidence of adenocarcinomas has been rising during the past few decades. This article discusses the epidemiology and pathogenesis of the squamous cell carcinoma, its clinical and histologic features, including microinvasive carcinoma, its histologic grade, and variant tumors. The prognostic impact of these features and the differential diagnosis are also covered. The second portion of this article is devoted to the glandular tumors of the cervix, including adenocarcinoma in situ and invasive adenocarcinoma and its variants. The differential diagnosis of these tumors with tumor like glandular lesions is given special attention. Finally, less common malignant cervical tumors are covered, with an emphasis being placed on their significance.

Endocervical glandular lesions: controversial aspects and ancillary techniques

The incidence of malignant and premalignant endocervical glandular lesions is increasing. This review covers controversial and difficult aspects regarding the categorisation and diagnosis of these lesions. The terminology of premalignant endocervical glandular lesions is discussed because of the differences between the UK terminology and the widely used World Health Organisation classification. The morphology and histological subtypes of premalignant endocervical glandular lesions are described. Early invasive adenocarcinoma and difficulties in the diagnosis and recognition of this entity are covered, as is the measurement of early invasion within cervical adenocarcinoma. Several benign endocervical glandular lesions can mimic malignant and premalignant endocervical glandular lesions, and the distinction of these benign mimics from premalignant and malignant lesions using ancillary immunohistochemical studies is also covered. Antibodies used to distinguish between endometrial and endocervical adenocarcinoma, in the diagnosis of cervical minimal deviation adenocarcinoma of mucinous type (adenoma malignum), and in the diagnosis of cervical mesonephric lesions are also reviewed.