p16 Expression in Squamous and Trophoblastic Lesions of the Upper Female Genital Tract:

Pathology of Gestational Trophoblastic Disease (GTD)

Gestational trophoblastic disease (GTD), comprising hydatidiform moles (HM) and gestational trophoblastic tumors (GTT), is extremely rare. HM originate from villous trophoblast and are considered preneoplastic. GTT originate from the intermediate, largely extravillous trophoblast and includes choriocarcinoma, placental site trophoblastic tumor, epitheloid trophoblastic tumor, and mixed trophoblastic tumor. The abnormal (non-molar) villous lesions, non-malignant tumour-like conditions, and non-gestational tumors add to the diagnostic dilemma. The correct diagnosis and classification of these rare conditions are important. This review intends to provide an update on changes in the World Health Organization classification and focusses on the morphologic aspects in diagnosis of GTD.

Incidence and Clinicopathologic Characteristics of Human Papillomavirus-independent Invasive Squamous Cell Carcinomas of the Cervix: A Morphologic, Immunohistochemical, and Human Papilloma-Virologic Study of 670 Cases

We aimed to determine the frequency of human papillomavirus-independent (HPVI) cervical squamous cell carcinoma (SCC) and to describe clinicopathologic characteristics. Among 670 patients with surgically treated SCCs in an established multi-institutional cohort, 447 had available tissue. Tissue microarrays were constructed and studied by in situ hybridization (ISH) for high-risk and low-risk human papillomavirus (HPV) mRNA and immunohistochemistry for p16 and p53. Tumors were HPVI if negative by HPV ISH and they failed to show diffuse p16 positivity by immunohistochemistry, and human papillomavirus-associated (HPVA) if positive by HPV ISH. Ten HPVI SCCs and 435 HPVA SCCs were identified; 2 cases were equivocal and excluded from analysis. The overall rate of HPVI SCC was low (2%) but was higher among older patients (7% in patients above 60 y of age and 17% in patients above 70 y of age). Compared with HPVA, patients with HPVI SCC were significantly older (median age, 72 vs. 49, P <0.001) and diagnosed at a higher stage (40% vs. 18% with stage III/IV disease, P =0.055). p53 expression was varied; 2 cases (20%) had null expression and 8 (80%) had wild-type expression. HPVI SCCs were heterogenous, with keratinizing, nonkeratinizing, and warty morphologies observed. Several cases had a precursor lesion reminiscent of differentiated vulvar intraepithelial neoplasia, with prominent basal atypia and hypereosinophilia or a basaloid-like morphology. Two patients (20%) had distant recurrences within 12 months, and 3 (30%) died of disease during follow-up. HPVI SCCs are rare tumors that are more common among older patients with higher stage disease and have important clinical and histologic differences from HPVA SCCs.

Molecular Analysis of HPV-independent Primary Endometrial Squamous Cell Carcinoma Reveals TP53 and CDKN2A Comutations : A Clinicopathologic Analysis With Re-evaluation of Diagnostic Criteria

Human papillomavirus (HPV)-independent primary endometrial squamous cell carcinoma (PESCC) is a rare but aggressive subtype of endometrial carcinoma for which little is known about the genomic characteristics. Traditional criteria have restricted the diagnosis of PESCC to cases without any cervical involvement. However, given that modern ancillary techniques can detect HPV and characteristic genetic alterations that should identify the more common mimics in the differential diagnosis, including endometrial endometrioid carcinoma with extensive squamous differentiation and HPV-associated primary cervical squamous cell carcinoma, those criteria may benefit from revision. To further characterize PESCC, we identified 5 cases of pure squamous cell carcinoma dominantly involving the endometrium that had the potential to be PESCC: 1 case involving only the endometrium and 4 cases with some involvement of the cervix. Clinicopathologic features were assessed and immunohistochemical analysis (p16, estrogen receptor, progesterone receptor, and p53), HPV RNA in situ hybridization (high-risk and low-risk cocktails and targeted probes for 16 and 18), and molecular studies were performed. All tumors showed aberrant/mutation-type p53 expression, were negative for estrogen receptor, progesterone receptor, and p16, and had no detectable HPV. Per whole-exome sequencing, 4 of the 5 tumors demonstrated comutations in TP53 and CDKN2A (p16). Four patients died of disease within 20 months (range, 1 to 20 mo; mean, 9 mo), and 1 patient had no evidence of disease at 38 months. PESCC represents a unique, clinically aggressive subtype of endometrial cancer with TP53 and CDKN2A comutations. This characteristic profile, which is similar to HPV-independent squamous cell carcinoma of the vulva, is distinct from endometrioid carcinoma with extensive squamous differentiation and HPV-associated primary cervical squamous cell carcinoma and can be used to distinguish PESCC from those mimics even when cervical involvement is present. Diagnostic criteria for PESCC should be relaxed to allow for cervical involvement when other pathologic features are consistent with, and ancillary techniques are supportive of classification as such.

PAX8 Positivity, Abnormal p53 Expression, and p16 Negativity in a Primary Endometrial Squamous Cell Carcinoma: A Case Report and Review of the Literature

Primary endometrial squamous cell carcinoma (PESCC) is a rare entity. As the clinicopathologic features and the immunophenotype have not been completely defined yet, here we report our experience and review of the literature on this topic. A 73-yr-old nulliparous woman presented with pelvic pain and vaginal bleeding. Endometrial biopsy showed a carcinoma with squamous differentiation infiltrating the myometrium. Total hysterectomy with bilateral salpingo-oophorectomy and selective pelvic lymphadenectomy was performed. Definitive diagnosis was squamous carcinoma of the endometrium, with one lymph node metastasis (stage IIIC1). Immunohistochemistry evidenced immunoreactivity of the tumor cells for cytokeratin 5, p63, cytokeratin 7, PAX8, PTEN, and cyclin D1, aberrant p53 overexpression, and Ki-67 reactivity in ~70% of the tumor cells. Estrogen and progesterone receptor, PAX2, WT1, and p16 were negative. Our case was the first PAX8-positive PESCC in the literature, underlining the Mullerian system origin of this neoplasm. Abnormal p53 expression of this case confirmed its role in the pathogenesis of PESCC. Further studies on a large number of cases are needed to better understand the pathologic features and the immunophenotype of PESCC.

Pathology of gestational trophoblastic disease (GTD)

Gestational trophoblastic disease (GTD) is subclassified into hydatidiform mole (HM), gestational trophoblastic tumours (GTT) and non-neoplastic trophoblastic lesions. HM, partial and complete, originate from villous trophoblast and are considered as preneoplastic conditions. The risk for the development of persistent GTD, mostly as invasive HM, ranges from 0.5% to 20%, which depends on the type of molar pregnancy. The risk of development of trophoblastic tumour after PHM is <0.5% and 2%-3% after CHM. GTT represent a spectrum of neoplasms that originates from the intermediate, largely extravillous, trophoblast and these include choriocarcinoma (CC), placental site trophoblastic tumour (PSTT), epithelioid trophoblastic tumour (ETT) and mixed trophoblastic tumour. Among tumour like conditions, exaggerated placental site reaction (EPSR) and placental site nodule (PSN) (s)/plaque (s) are included. The morphological appearances of HM can be mimicked by abnormal (non-molar) villous lesions, and similarly, GTT can be mimicked both by non-malignant tumour-like conditions and non-gestational tumours with trophoblastic differentiation, which add to the diagnostic dilemma of these rare conditions. GTT have a favourable prognosis and better response to specific chemotherapeutic regimens when compared with non-gestational malignant genital tract neoplasms. The correct diagnosis and classification of these rare conditions are therefore important. This article focusses on the morphological appearances, immunocytochemistry as an aid in the diagnosis and the changes in current WHO classification of GTDs (WHO 2020).

Squamous differentiation portends poor prognosis in low and intermediate-risk endometrioid endometrial cancer

BACKGROUND

Endometrial cancer presents well-defined risk factors: myometrial invasion, histological subtype, tumor grade, lymphovascular space invasion (LVSI). Some low and intermediate-risk endometrioid endometrial cancer patients exhibited unexpected outcomes. This study aimed to investigate other clinical-pathological factors that might influence the recurrence rates of patients diagnosed with low and intermediate-risk endometrioid endometrial cancer.

METHODS

A case-control study from a cohort retrospective of 196 patients diagnosed with low and intermediate-risk endometrioid endometrial cancer at a single institution from 2009 to 2014 was conducted. Medical records were reviewed to compare clinical (race, smoking, menopause age, body mass index) and pathological (endometrioid vs endometrioid with squamous differentiation, tumor differentiation grade, tumor location, endocervical invasion, LVSI) features of patients with recurrence (case) and without recurrence (control) of disease. Three controls for each case were matched for age and staging.

RESULTS

Twenty-one patients with recurrence were found (10.7%), of which 14 were stage IA, and 7 were stage IB. In accordance, 63 patients without recurrence were selected as controls. There were no significant differences in any clinical characteristics between cases and controls. Among pathological variables, presence of squamous differentiation (28.6% vs. 4.8%, p = 0.007), tumor differentiation grade 2 or 3 (57.1% vs. 30.2%, p = 0.037) and presence of endocervical invasion (28.6% vs. 12.7%, p = 0.103) were associated with disease recurrence on a univariate analysis. On multivariable analysis, only squamous differentiation was a significant risk factor for recurrence (p = 0.031).

CONCLUSION

Our data suggest that squamous differentiation may be an adverse prognostic factor in patients with low and intermediate-risk endometrioid endometrial cancer, that showed a 5.6-fold increased risk for recurrence.

Practical issues in uterine pathology from banal to bewildering: the remarkable spectrum of smooth muscle neoplasia

Among mesenchymal tumors of the uterus, smooth muscle neoplasms are most common. The wide morphologic spectrum, especially within the category of leiomyomas, is responsible for diagnostic problems more frequently with leiomyosarcoma (including mitotically active, apoplectic, and leiomyoma with bizarre nuclei) but also with endometrial stromal tumors. In the former scenario, clinical information, gross appearance as well as strict utilization of morphologic criteria including cytologic atypia, mitotic activity, and tumor cell necrosis are clues in establishing the correct diagnosis. It is important to keep in mind that mitotic rate thresholds vary for the different subtypes of leiomyosarcoma. Of note, p16 should be used with caution in supporting a diagnosis of leiomyosarcoma as it is often positive in leiomyomas with bizarre nuclei and leiomyomas with apoplectic change (in the latter most frequently and more intense near areas of necrosis). MED12 mutations have also a very limited role in this differential diagnosis. Endometrial stromal tumors are by far, less common than smooth muscle tumors, but can be confused with leiomyosarcomas if they are associated with an undifferentiated uterine sarcoma and the low-grade component is overlooked or they have a myxoid/fibroblastic morphology. The differential diagnosis may be confounded if the latter is associated with a high-grade endometrial stromal sarcoma. It is important to highlight that CD10 is not a reliable marker in these differentials and should be used as a part of a panel of antibodies that also includes desmin and h-caldesmon. Two other recently categorized tumors in the uterus that merit special mention are PEComa and inflammatory myofibroblastic tumor as they enter in the differential diagnosis of smooth muscle tumors. PEComa may be part of the tuberous sclerosis syndrome and may show either a predominantly epithelioid or spindle morphology or combination thereof. Rarely, it may contain melanin pigment. There is variable positivity for HMB-45, MelanA, MiTF, and CathepsinK, and some tumors have been shown to express TFE-3 especially when associated with "clear cell" morphology. Patients with adverse outcome have tumors with ≥2 of the following features: ≥5 cm, infiltration, high-grade cytologic features, mitotic rate ≥1/50 high-power fields, necrosis, or lymphovascular invasion. Inflammatory myofibroblastic tumor is important to recognize as it often mimics myxoid smooth muscle tumors, either benign or malignant. The presence of an associated lymphoplasmacytic infiltrate should alert to that possibility and ALK studies (immunostain or FISH) are helpful in establishing this diagnosis. These tumors can behave in a malignant manner if large, associated with abundant myxoid change, brisk mitotic rate or show tumor cell necrosis.

A rare case of HPV-negative cervical squamous cell carcinoma

It is generally assumed that virtually all cervical squamous cell carcinomas are associated with persistent infection by high-risk human papillomavirus (HPV), although it is well known that unusual variants of cervical adenocarcinoma are mostly HPV negative. We report a case of a well-differentiated cervical squamous cell carcinoma in a 54-yr-old woman, the morphologic features of which suggested a non-HPV-related neoplasm. The tumor was p16 negative. HPV was also negative by 2 methods, including the highly sensitive SPF-10 system. Further study of additional cases is needed to establish the etiological and pathogenetic factors that underlie very rare non-HPV-related cervical squamous cell carcinoma.

GATA-3 expression in trophoblastic tissues: an immunohistochemical study of 445 cases, including diagnostic utility

Immunohistochemical expression of GATA-3 is seen predominantly in non-neoplastic bladder and breast epithelium and their respective carcinomas; however, data on expression in normal and lesional trophoblastic tissues are limited. Immunohistochemical staining for GATA-3 was assessed in a range of normal/lesional trophoblastic tissues and tumors in the differential diagnosis (n=445), including nonmolar products of conceptions/second and third trimester placentas/ectopic pregnancies, hydatidiform moles, placental site nodules, normal/exaggerated implantation sites, choriocarcinomas, epithelioid trophoblastic tumors, placental site trophoblastic tumors, atypical smooth muscle tumors (including leiomyosarcoma), and cervical and pulmonary squamous cell carcinomas. The extent of expression (0 to 4+) and intensity (weak to strong) were recorded. All cases with developing trophoblast/non-neoplastic trophoblastic proliferation and 81% of trophoblastic neoplasms were positive. Of all non-neoplastic trophoblast cell types, expression was observed in cytotrophoblast in 89% of cases, syncytiotrophoblast in 50%, intermediate trophoblast in 100%, and villous trophoblastic columns in 100%. Increasing gestational age was associated with a decrease in extent/intensity of expression in non-neoplastic cytotrophoblast and syncytiotrophoblast, whereas intermediate trophoblast maintained diffuse and strong expression from early to late gestation (P<0.0001). Eighty-nine percent of normal/exaggerated implantation sites showed 3+ or 4+ expression, whereas staining in 55% of placental site nodules was 1+ or 2+. Staining for GATA-3 was present in 78% of choriocarcinomas, 95% of epithelioid trophoblastic tumors, and 71% of placental site trophoblastic tumors. Although the number of choriocarcinomas and placental site trophoblastic tumors that showed a spectrum of expression ranging from negative to diffuse was relatively evenly distributed, 81% of epithelioid trophoblastic tumors had 3+ or 4+ staining. None of the atypical smooth muscle tumors and 3% of squamous cell carcinomas were positive, all of which exhibited weak staining. We conclude that GATA-3 is frequently expressed in normal and lesional trophoblastic tissues. It is also differentially expressed in intermediate trophoblast and cytotrophoblast/syncytiotrophoblast, which varies according to time during pregnancy. This study expands the spectrum of neoplasms known to express GATA-3. Thus, recognition of expression in trophoblastic tumors is important, because it can present a diagnostic pitfall in the assessment of suspected metastatic bladder or breast carcinomas involving the gynecologic tract. In the evaluation of diagnostically problematic tumors for which trophoblastic neoplasms are in the differential diagnosis, such as leiomyosarcoma and squamous cell carcinoma, GATA-3 can be included as part of an immunohistochemical panel particularly when other trophoblastic markers are either not available or yield ambiguous results.

The spectrum of cervical glandular neoplasia and issues in differential diagnosis

CONTEXT

Premalignant and malignant glandular lesions of the cervix are known to often cause diagnostic problems with a variety of benign (more common) as well as other malignant mimics, the latter setting often being represented by secondary involvement by endometrioid endometrial carcinoma especially in small samplings.

OBJECTIVE

To highlight key histologic features and immunohistochemical markers that may be helpful in the distinction of in situ endocervical carcinoma from benign glandular proliferations, and those that separate different subtypes of invasive endocervical carcinoma, as well as invasive carcinoma from other carcinomas secondarily involving the cervix and nonneoplastic proliferations of the cervix.

CONCLUSIONS

Clinical and morphologic features as well as immunohistochemistry results should be used in conjunction in the differential diagnosis of glandular proliferations of the cervix, as correct interpretation has major clinical consequences for the patient in most instances (especially benign versus malignant). Immunohistochemical markers should be used as part of a panel of antibodies, as exceptions may occur to the usual pattern of staining, and if used singly, they may mislead the pathologist to establish a wrong diagnosis.

High-Grade Endometrial Carcinomas

High-grade endometrial carcinomas are a heterogeneous group of clinically aggressive tumors. They include FIGO grade 3 endometrioid carcinoma, serous carcinoma, clear cell carcinoma, undifferentiated carcinoma, and malignant mixed Müllerian tumor (MMMT). Epidemiologic, genetic, biologic prognostic and morphologic differences between these entities are striking in prototypic cases, yet substantial overlap exists and diagnostic criteria and therapeutic approaches that account for the group's diversity are currently insufficient. FIGO grade 3 endometrioid carcinoma demonstrates solid, trabecular or nested growth and may resemble poorly differentiated squamous cell carcinoma. Endometrioid glandular differentiation is usually focally present. Serous carcinoma usually displays papillary architecture but glandular and solid patterns may predominate. Tumor cells typically display diffuse and severe atypia. Clear cell carcinoma should be diagnosed by recognizing characteristic papillary or tubulocystic architecture with cuboidal tumor cells showing atypical but uniform nuclei. Cells with clear cytoplasm are frequently but not always present. On the other hand, clear cells may be encountered in endometrioid and serous carcinomas. Immunohistochemical stains for p53, p16, ER, PR, mib-1, hepatocyte nuclear factor 1β and pan-cytokeratin can be helpful in classifying these high-grade carcinomas. They should be used in concert with thorough morphologic examination, as part of a rational panel of markers and only in specific circumstances. Although these tumors may appear clinically and even morphologically similar, demographic and epidemiologic features as well as patterns of spread and treatment modalities differ.