W. Glenn McCluggage

Morphological subtypes of ovarian carcinoma: a review with emphasis on new developments and pathogenesis

Ovarian carcinomas comprise a heterogeneous group of neoplasms, the four most common subtypes being serous, endometrioid, clear cell and mucinous. In recent years, our understanding of the underlying pathogenesis and initiating molecular events in the different tumour subtypes has greatly increased, and although ovarian carcinoma is often considered clinically as one disease, there is now a much greater realisation that the various subtypes have a different natural behaviour and prognosis. At present, adjuvant therapy is mainly dependent upon tumour stage and grade rather than type; however, this is likely to change in the future with the development of new chemotherapeutic agents and targeted therapies and clinical trials are necessary to evaluate the efficacy of different agents in clear cell, mucinous and low grade serous carcinomas, neoplasms which are considered relatively resistant to traditional chemotherapeutic regimes. In this review, the major subtypes of ovarian carcinoma are discussed. It is now firmly established that there are two distinct types of ovarian serous carcinoma, low grade and high grade, the former being much less common and arising in many cases from a serous borderline tumour. Low grade and high grade serous carcinoma represent two distinct tumour types with a different underlying pathogenesis rather than low grade and high grade variants of the same neoplasm. Both are usually advanced stage (stage III or IV) at diagnosis. B-raf and k-ras mutations are important molecular events in low grade serous carcinomas while high grade serous carcinomas are almost always associated with TP53 mutation. There is now emerging and compelling evidence that many high grade serous carcinomas (by far the most common subtype of ovarian carcinoma) actually arise from the epithelium of the distal fallopian tube. Future studies regarding the initiating molecular events in the development of this aggressive neoplasm should concentrate on this site. Primary ovarian mucinous carcinomas are uncommon, almost always unilateral and stage I, and largely of so-called intestinal or enteric type. Most arise in a stepwise manner from a pre-existing mucinous cystadenoma and mucinous borderline tumour. Endometrioid and clear cell carcinomas typically present as low stage neoplasms and in many, or most, cases arise from endometriosis; the former are usually well differentiated and there is now evidence that the majority of neoplasms reported in the past as high grade endometrioid carcinoma are of serous type. WT1 is useful in this regard since it is a relatively specific marker of a serous phenotype. It is recommended that different subtypes of ovarian carcinoma are graded using different systems rather than employing a universal grading system.

Germline and somatic SMARCA4 mutations characterize small cell carcinoma of the ovary, hypercalcemic type

Small cell carcinoma of the ovary, hypercalcemic type (SCCOHT) is the most common undifferentiated ovarian malignancy in women under 40 years of age. We sequenced the exomes of six individuals from three families with SCCOHT. After discovering segregating deleterious germline mutations in SMARCA4 in all three families, we tested DNA from a fourth affected family, which also carried a segregating SMARCA4 germline mutation. All the familial tumors sequenced harbored either a somatic mutation or loss of the wild-type allele. Immunohistochemical analysis of these cases and additional familial and non-familial cases showed loss of SMARCA4 (BRG1) protein in 38 of 40 tumors overall. Sequencing of cases with available DNA identified at least one germline or somatic deleterious SMARCA4 mutation in 30 of 32 cases. Additionally, the SCCOHT cell line BIN-67 had biallelic deleterious mutations in SMARCA4. Our findings identify alterations in SMARCA4 as the major cause of SCCOHT, which could lead to improvements in genetic counseling and new treatment approaches.

A panel of immunohistochemical stains, including carcinoembryonic antigen, vimentin, and estrogen receptor, aids the distinction between primary endometrial and endocervical adenocarcinomas

The histological distinction between a primary endometrial and a primary endocervical adenocarcinoma is often difficult, especially in small biopsy specimens. A preoperative distinction is important because primary surgical management differs between the two tumors. Cases of primary endometrioid endometrial (n=30) and primary endocervical (n=26) adenocarcinoma of endocervical type were stained immunohistochemically with the monoclonal antibodies against carcinoembryonic antigen (CEA), vimentin, estrogen receptor (ER), and 34&bgr;E12. In all cases the origin of the adenocarcinoma was confirmed by examination of the definitive pathology specimen. There was diffuse positive nuclear staining for ER in 28 of 30 (93%) endometrial adenocarcinomas. ER was negative in 16 of 26 endocervical adenocarcinomas, and there was focal weak nuclear staining in the other cases. Vimentin was positive in 29 of 30 (97%) endometrial adenocarcinomas but in only 2 of 26 (8%) endocervical adenocarcinomas. CEA was positive in 25 of 26 (96%) endocervical adenocarcinomas, mostly with diffuse membranous and cytoplasmic staining. Positivity with CEA was present in 21 of 30 (70%) endometrial adenocarcinomas but was largely confined to squamoid areas with only 12 tumors exhibiting focal membranous staining of the glandular component. 34&bgr;E12 was diffusely positive in all except one cervical adenocarcinoma. In endometrial carcinomas, positivity was strongest in squamoid areas but there was positive staining, either focally or diffusely, of the glandular component in 27 cases. In summary, primary endometrioid endometrial adenocarcinomas are characterized by diffuse, strong, positive staining for vimentin and ER and negative or very focal, positive staining of the glandular component for CEA. In contrast, primary endocervical adenocarcinomas are characterized by CEA positivity, which is usually but not always diffuse, negativity for vimentin, and negativity or focal weak positivity for ER. 34&bgr;E12 is of no value in the distinction between endometrial and endocervical adenocarcinomas. A panel of immunohistochemical stains, comprising CEA, vimentin, and ER, generally allows confident preoperative distinction between a primary endometrial and endocervical adenocarcinoma.

Thyroid transcription factor-1 expression in endometrial and endocervical adenocarcinomas.

Thyroid transcription factor-1 (TTF-1) is widely used in the diagnosis of lung and thyroid carcinomas. Although there have been reports of TTF-1 immunoreactivity in tumors other than those originating in the lung or thyroid, endocervical and endometrial adenocarcinomas have not been studied in large numbers. Our study provides data regarding the incidence and distribution of TTF-1 expression in these tumors. Twenty-eight endocervical (9 well, 12 moderately, and 7 poorly differentiated), 32 endometrioid endometrial adenocarcinomas (11 grade I, 8 grade II, and 13 grade III), and 13 uterine serous carcinomas were retrieved and stained with TTF-1. None of the tumors had a neuroendocrine component. The hematoxylin and eosin and anti-TTF-1 antibody stained sections were reviewed, and the presence and distribution of TTF-1 nuclear positivity was recorded. A semiquantitative grading system used to evaluate the distribution of TTF-1 staining (0=negative, 1+=<5%, 2+=5% to 25%, 3+=26% to 50%, 4+=51% to 75%, and 5+=>75%). TTF-1 expression was seen in 1 of 28 (4%) of the endocervical adenocarcinomas and this was 4+ in distribution. The positive endocervical carcinoma was poorly differentiated. TTF-1 expression was present in 6 of 32 (19%) of the endometrioid adenocarcinomas (1 grade I, 2 grade II, and 3 grade III) and varied from 1+ to 4+ in distribution. Only 2 of 32 (6%) of the endometrioid adenocarcinomas stained diffusely (4+). There was no apparent correlation between the degree of differentiation and TTF-1 positivity in the adenocarcinomas. Three of 13 (23%) serous carcinomas were also positive (1 case 5+ and 2 cases 1+). Although TTF-1 is generally considered to be a relatively specific marker for lung and thyroid neoplasms, the occasional expression of endometrial and endocervical carcinomas should be kept in mind when evaluating neoplasms of uncertain origin. It should also be taken into consideration in the evaluation of adenocarcinomas involving the lung in patients with a history of a gynecologic malignancy.

Immunohistochemical staining of ovarian granulosa cell tumors with monoclonal antibody against inhibin

Inhibin is a peptide hormone produced by ovarian granulosa cells and by granulosa cell tumors. Serum inhibin measurements have been used as a biochemical marker of the presence or progression of ovarian granulosa cell tumors and their metastases. In the current study, an antibody against the alpha-subunit of human inhibin was used to stain 16 cases of ovarian adult granulosa cell tumors, 15 cases of other ovarian sex cord-stromal tumors, and 51 cases of a range of ovarian and extraovarian neoplasms, many of which may mimic granulosa cell tumor. There was diffuse strong cytoplasmic staining of all cases of adult granulosa cell tumor. Diffuse positive staining also was observed in all Leydig cell tumors, and there was focal staining in a proportion of fibrothecomas. There was focal weak staining of one case of ovarian clear cell carcinoma but no staining of other ovarian and extraovarian neoplasms. Immunohistochemical staining with antibodies against inhibin is of value in the diagnosis of granulosa cell tumor and in the distinction of this neoplasm from others that may mimic it. The antibody also may be useful for the confirmation of late metastasis of granulosa cell tumor, especially when the previous history is not known.

Thyroid transcription factor-1 expression in ovarian epithelial neoplasms

Thyroid transcription factor-1 (TTF-1) protein expression is widely used in the diagnosis of lung and thyroid carcinomas. Although there have been reports of TTF-1 immunoreactivity in tumors other than those originating in the lung or the thyroid, the expression of this marker has been studied in only a limited number of ovarian neoplasms. Our study examines the incidence of TTF-1 expression in a variety of ovarian epithelial neoplasms. Tissue microarrays of 138 ovarian serous carcinomas, 65 endometrioid adenocarcinomas, 35 mucinous adenocarcinomas, 30 mucinous neoplasms of low malignant potential, and 10 clear cell carcinomas were stained with anti-TTF1-antibody. In addition, whole tissue sections of 19 serous carcinomas, 5 endometrioid adenocarcinomas, 7 mucinous adenocarcinomas, and 3 clear cell carcinomas were stained. In the tissue microarrays, TTF-1 nuclear expression was demonstrated in 2 of 65 (3%) of the endometrioid adenocarcinomas; no nuclear immunoreactivity was identified in the remaining ovarian neoplasms. In the whole tissue sections, TTF-1 nuclear staining was present in 7 of 19 (37%) serous carcinomas, 1 of 5 (20%) endometrioid adenocarcinomas, and 1 of 3 (33%) clear cell carcinomas. In most of the positive cases, staining was focal, but in one endometrioid adenocarcinoma in the tissue microarray and in one serous and one clear cell carcinoma in the whole tissue sections, there was diffuse positivity. Overall, there was nuclear staining in 0.7% of tumors in the tissue microarray and 26% in the whole tissue sections. Although TTF-1 nuclear expression is generally considered to be a relatively specific marker for lung and thyroid neoplasms, the occasional immunoreactivity of ovarian carcinomas should be considered in the evaluation of neoplasms of unknown primary origin. It should also be taken into consideration when evaluating adenocarcinomas involving the lung in patients with a history of a gynecologic malignancy.

Ovarian neoplasms composed of small round cells: a review.

Ovarian neoplasms composed predominantly or exclusively of small round cells with scant cytoplasm are relatively rare. However, there is a wide differential, and pathologists often struggle to make a correct diagnosis because of overlapping histologic features. Perhaps the best known of these neoplasms is ovarian small cell carcinoma of hypercalcemic type (OSCCHT), a tumor of unknown histogenesis. This may be confused with a wide range of neoplasms ranging from sex cord-stromal tumors (some of which may exhibit a small cell phenotype) to neoplasms in the family of small round blue cell tumor to various undifferentiated malignancies. A neuroendocrine small cell carcinoma, so-called small cell carcinoma of pulmonary type, may also arise within the ovary, and this may be a component of a typical ovarian surface epithelial-stromal tumor. In addition to the well-known family of small round blue cell tumors of childhood, other small cell neoplasms that may arise within the ovary or involve the ovary include intra-abdominal desmoplastic small round cell tumor, metastatic small cell carcinoma, peripheral and central primitive neuroectodermal tumor, and endometrial stromal sarcoma. Malignant melanoma, undifferentiated carcinoma, and various germ cell tumors, especially dysgerminoma and immature teratoma, also on occasion enter into the differential diagnosis of an ovarian small cell neoplasm. In this review, the morphologic features of some of these neoplasms are described, as is the value of immunohistochemistry and other ancillary techniques in establishing a diagnosis.

Genomic analysis reveals the molecular heterogeneity of ovarian clear cell carcinomas.

Purpose: Ovarian clear cell carcinomas (OCCC) are a drug-resistant and aggressive type of epithelial ovarian cancer. We analyzed the molecular genetic profiles of OCCCs to determine whether distinct genomic subgroups of OCCCs exist. Experimental design: Fifty pure primary OCCCs were subjected to high-resolution microarray-based comparative genomic hybridization (aCGH). Unsupervised hierarchical clustering using Wards linkage analysis was performed to identify genomic subgroups of OCCCs. Survival analysis was performed using Kaplan–Meier method and log-rank test. Cox-regression analysis was used to identify independent predictors of outcome. Differentially amplified regions between genomic subgroups of OCCCs were identified using a multi-Fishers exact test. Results: Hierarchical cluster analysis revealed two distinct clusters of OCCCs with different clinical outcomes. Patients from cluster-1 had a significantly shorter median progression-free survival (PFS) than those from cluster-2 (11 vs. 65 months, P = 0.009), although estimates for ovarian cancer–specific survival (OCS) did not reach statistical significance (P = 0.065). In multivariate analysis, suboptimal debulking surgery and genomic cluster were independently prognostic for PFS. Recurrently amplified genomic regions with a significantly higher prevalence in cluster-1 than cluster-2 OCCCs were identified and validated. HER2 gene amplification and protein overexpression was observed in 14% of OCCCs, suggesting that this may constitute a potential therapeutic target for a subgroup of these tumors. Conclusions: OCCCs constitute a heterogeneous disease at the genomic level despite having similar histological features. The pattern of genomic aberrations in subgroups of OCCCs is of clinical significance. We have identified recurrently amplified regions that may harbor potential therapeutic targets for subgroups of OCCCs. Clin Cancer Res; 17(6); 1521–34. ©2011 AACR.

A multistep model for ovarian tumorigenesis: the value of mutation analysis in the KRAS and BRAF genes.

Epithelial ovarian tumours represent a complex group of histological subtypes and there has long been controversy over the question of a precursor lesion for these neoplasms. The application of mutation analysis of the KRAS and BRAF genes (members of the RAS‐RAF‐MEK‐ERK‐MAP kinase pathway) is consistent with the model for progression of mucinous carcinomas and a subset of serous carcinomas (the so‐called low‐grade serous carcinomas) through benign and borderline lesions. The relatively high incidence of BRAF and KRAS mutations in serous borderline tumours and low‐grade serous carcinomas, and their extremely low incidence/absence in high‐grade serous carcinomas, provide strong evidence that high‐grade carcinomas do not arise through this intermediate step. Copyright

An immunohistochemical study of cervical neuroendocrine carcinomas: Neoplasms that are commonly TTF1 positive and which may express CK20 and P63.

Cervical small cell neuroendocrine carcinoma (SCNEC) and large cell neuroendocrine carcinoma (LCNEC) are uncommon but highly aggressive neoplasms. From a diagnostic point of view, there may be problems both in distinguishing these from other neoplasms and in confirming a cervical origin. This is important as management is critically dependent on the correct histologic diagnosis. We undertook a detailed immunohistochemical analysis of a relatively large series of primary cervical SCNEC (n=13) and LCNEC (n=8). Cases were stained with AE1/3, chromogranin, CD56, synaptophysin, PGP9.5, TTF1, p16, p63, CK7, CK20, neurofilament, and CD99. CK20 and neurofilament staining was undertaken to investigate whether some of these neoplasms might exhibit a Merkel cell immunophenotype and CD99 staining to assess whether there is immunohistochemical overlap with neoplasms in the Ewing family of tumors (EFT). For all markers, staining was classified as negative, 1+ (<10% cells immunoreactive), 2+ (10 to 50% cells immunoreactive), or 3+ (>50% cells immunoreactive). Eleven and 6 SCNEC and LCNEC, respectively were positive with AE1/3. Chromogranin, CD56, synaptophysin, and PGP9.5 were positive in 11, 19, 19, and 9 cases, respectively. Altogether 15 cases (71%) (11 SCNEC, 4 LCNEC) exhibited nuclear positivity, often diffuse, with TTF1. All but 1 case was diffusely positive with p16. p63 was positive in 9 cases, including 5 with diffuse nuclear immunoreactivity. Ten and 4 neoplasms were positive with CK7 and CK20, respectively. Neurofilament was positive in 7 tumors. The 4 neoplasms that were CK20 positive were stained with the monoclonal antibody CM2B4, generated against an antigenic epitope on the Merkel cell polyomavirus T antigen; all were negative. CD99 was positive in 6 cases. In 2 cases, adjacent foci of adenocarcinoma in situ (AIS) contained scattered individual chromogranin positive cells, raising the possibility that some cervical neuroendocrine carcinomas arise from neuroendocrine cells in AIS. Four of 13 cases of pure AIS also contained scattered chromogranin positive cells. Our results illustrate that a proportion of cervical neuroendocrine carcinomas are negative with broad spectrum cytokeratins and some of the commonly used neuroendocrine markers. TTF1 positivity is extremely common and may be a useful marker of a neuroendocrine carcinoma. It is of no value in exclusion of a pulmonary primary. p16 is almost always positive in cervical neuroendocrine carcinomas, possibly owing to an association with oncogenic human papillomavirus, although other mechanisms of expression are also possible. Cervical neuroendocrine carcinomas may be p63 positive, illustrating that this marker is not specific for squamous differentiation. CK20 and neurofilament positivity in some cervical neuroendocrine carcinomas is in keeping with a Merkel cell immunophenotype, similar to that described in SCNECs in other organs. However, the absence of staining with CM2B4 argues against a true Merkel cell tumor. CD99 staining in a cervical neuroendocrine carcinoma should not result in misdiagnosis as a neoplasm in the Ewing family of tumors.