Dedifferentiated Ovarian Carcinoma with ARID1A and ARID1B Mutations: A Clinicopathological Report and Literature Review

Dedifferentiated carcinoma of the female genital tract is a relatively recently recognized aggressive tumor affecting predominantly perimenopausal and postmenopausal women. In addition to having an undifferentiated component, dedifferentiated carcinoma includes a juxtaposed endometrioid adenocarcinoma, FIGO grade 1 or 2. Molecular characterization of these tumors has been a subject of discussion in multiple recent articles. We present a case of dedifferentiated carcinoma of the ovary in a 70-year-old female demonstrating concurrent inactivation of ARID1A and ARID1B. To the best of our knowledge, this is the second clinical report demonstrating dedifferentiated carcinoma of the ovary with concurrent inactivation of ARID1A and ARID1B. ARID1A and ARID1B inactivation seems to represent an alternate mechanism of switch/sucrose nonfermentable complex inactivation in the development of dedifferentiated carcinoma. Additional studies are warranted to precisely understand the molecular mechanism of cellular dedifferentiation in the dedifferentiated endometrial/ovarian carcinomas, thus guiding the development of targeted therapy.

ARID1B Immunohistochemistry Is an Important Test for the Diagnosis of Dedifferentiated and Undifferentiated Gynecologic Malignancies

Dedifferentiated and undifferentiated endometrial and ovarian carcinomas (DDC/UDC) are aggressive malignancies defined by morphologic and molecular undifferentiation, and associated with core SWI/SNF deficiency. Their main differential diagnoses include high-grade endometrial and ovarian carcinomas that often show overlapping morphologic and molecular profiles. Loss of cell lineage markers expression by immunohistochemistry (IHC) is commonly used to assist diagnosis, but it has poor specificity, while core SWI/SNF deficiency is much more specific. Approximately half of SWI/SNF-deficient DDC/UDC are associated with loss of ARID1B expression, yet, unlike the other core SWI/SNF proteins (SMARCA4 and SMARCB1), this test is rarely available, even in tertiary centers. Mutational testing for ARID1B is increasingly common among targeted DNA sequencing panels, but it is difficult to interpret in the absence of IHC results. Overall, the importance of including ARID1B IHC as part of the routine panel for undifferentiated gynecologic malignancies should be emphasized, especially as SWI/SNF inactivation is becoming a necessary biomarker for diagnostics, clinical management, and clinical trial enrollment.

ZEB1 expression is frequently detected in undifferentiated and dedifferentiated carcinomas, but is not specific among endometrial carcinomas

AIMS

The pathological diagnosis of undifferentiated and dedifferentiated endometrial carcinomas (UC/DCs) is prognostically important. However, undifferentiated components may be confused with other subtypes, particularly grade 3 endometrioid carcinomas (G3ECs). ZEB1 has recently been identified as a promising marker because it is frequently expressed in the undifferentiated components of UC/DCs, but not in other carcinomas. Therefore, we herein evaluated the diagnostic utility of ZEB1 with an emphasis on distinguishing between UC/DCs and G3ECs using an expanded cohort of endometrial carcinomas and carcinosarcomas.

METHODS AND RESULTS

Immunostaining for ZEB1 was performed on whole-tissue sections of 19 UC/DCs, 194 non-UC/DC endometrial carcinomas, and 29 carcinosarcomas. Staining was defined as negative (<5%), focal (5-50%), and diffuse expression (>50%). ZEB1 was expressed in 84% of the undifferentiated components of UC/DCs (diffuse in 14, focal in two). Focal expression was observed in eight non-UC/DC endometrial carcinomas and diffuse expression in seven, with the latter comprising G3ECs (4/76), serous carcinoma (1/37), clear cell carcinoma (1/21), and neuroendocrine carcinoma (1/3). Epithelial differentiation was morphologically and immunohistochemically less evident in G3ECs and neuroendocrine carcinoma with diffuse ZEB1 expression. All carcinosarcomas showed diffuse ZEB1 expression in their sarcomatous components.

CONCLUSION

Immunostaining for ZEB1 was sufficiently sensitive to detect undifferentiated components. Diffuse ZEB1 expression showed high specificity for distinguishing between undifferentiated components and G3ECs; however, ZEB1 expression was not entirely specific to UC/DCs. The integration of ZEB1 into the diagnosis of UC/DCs requires careful examinations to exclude other tumours, such as less differentiated G3ECs, neuroendocrine carcinomas, and carcinosarcomas.

Bilateral adrenal metastases of endometrial cancer with adrenal insufficiency

Adrenal metastasis from endometrial cancer is extremely rare and has a poor prognosis, especially for bilateral adrenal metastases. It is usually asymptomatic without any adrenal hormonal abnormalities. A 50-year-old postmenopausal woman presented with acute right-sided back pain and history of occasional abnormal uterine bleeding. She was diagnosed with endometrial cancer with ruptured bilateral adrenal metastases. She underwent total hysterectomy and bilateral salpingo-oophorectomy, and the pathological findings revealed dedifferentiated carcinoma. After three courses of adjuvant chemotherapy, the bilateral adrenal metastases had increased in size, with worsening back pain and adrenal hormone insufficiency. The patient died 6 months after the identification of adrenal tumors. Acute back pain may lead to the identification of a ruptured adrenal metastasis. The possibility of gradual adrenal insufficiency should be considered in bilateral adrenal metastases. Although the prognosis is poor, tumor debulking surgery followed by adjuvant chemotherapy could be suggested to improve the prognosis.

Dedifferentiated Mesonephric-like Adenocarcinoma of the Uterine Corpus

BACKGROUND/AIM

We present a case of uterine dedifferentiated mesonephric-like adenocarcinoma (MLA).

CASE REPORT

A 54-year-old woman underwent total hysterectomy for a uterine mass under the impression of a uterine sarcoma. Histologically, MLA exhibited various growth patterns including tubular and glandular architecture. Undifferentiated carcinoma (UC) displayed discohesive tumor cells without any obvious architecture. Immunohistochemically, UC was positive for epithelial markers in very few scattered tumor cells. MLA exhibited the wild-type p53 expression pattern, whereas UC showed a uniform and strong p53 immunoreactivity. Targeted sequencing analysis revealed an identical Kirsten rat sarcoma viral oncogene homolog (KRAS) mutation in both components. A pathogenic missense tumor protein 53 (TP53) mutation was detected in UC, but not in MLA.

CONCLUSION

The mutant p53 expression pattern exclusively detected in UC was concordant with the presence of missense TP53 mutation. Our observations suggested that TP53 mutation is associated with the possible transformation from MLA to UC.

Undifferentiated endometrial carcinoma arising in the background of high-grade endometrial carcinoma - Expanding the definition of dedifferentiated endometrial carcinoma

Dedifferentiated endometrial adenocarcinoma (DEC) is defined by the coexistence of undifferentiated carcinoma with low-grade (FIGO grade 1 or 2) endometrioid carcinoma. Few cases of DEC arising in the background of high-grade carcinoma (DEC-HG) have been reported, however, this phenomenon is poorly characterized. In this study we describe the morphologic, immunohistochemical and clinico-pathologic characteristics of DEC-HG. 18 DECs were diagnosed at our institution between 2008-2019, and in 11 (61%), the undifferentiated component was associated with high-grade carcinoma (8 endometrioid FIGO grade 3, 2 with ambiguous features, 1 serous). The remaining 7 (39%) represented DEC-LG (3 FIGO grade 1 and 4 FIGO grade 2). 7/11 (64%) patients with DEC-HG presented with advanced stage (FIGO stage III/IV), whereas most with DEC-LG (6/7, 86%) were stage I. On follow up, 2 patients in the DEC-HG group died of disease and 2 had progressive disease within 2 months of surgery. There was only one recurrence in the DEC-LG, 6 months post-surgery. The DEC component in both groups showed similar morphology and immunophenotype, with predominantly focal or complete loss of expression of pan-keratin, EMA, E-cadherin, CK8/18, PAX8 and ER. The DEC component in the DEC-HG group had wild-type p53 expression in 8/11 (73%) cases, loss of MLH1 and PMS2 in 6/11 (55%) and loss of SMARCA4 in 3/9 (33%). Although numbers are small, we show that DEC-HG is a previously under-recognized phenomenon, with morphologic and immunophenotypic similarities to DEC-LG, which supports expanding the definition of DEC to include DEC-HG. DEC-HG may be more aggressive than DEC-LG.

Cytologic features of undifferentiated and dedifferentiated carcinomas of the endometrium

BACKGROUND

Undifferentiated carcinoma (UC) is a rare, aggressive subtype of endometrial carcinoma. Dedifferentiated carcinomas (DCs) are UCs associated with a component of well differentiated endometrioid carcinoma. The authors sought to describe the morphologic features of UCs and DCs in cytologic specimens.

METHODS

Cytologic specimens from 23 women (aged 46-86 years; median age, 59 years) were reviewed, including cervicovaginal specimens (n = 7), peritoneal washings (n = 5), touch preparations of core biopsies from various sites (n = 5), fine-needle biopsies of lymph nodes (n = 3), ascitic fluid (n = 1), pleural fluid (n = 1), and intrauterine fluid (n = 1).

RESULTS

There were 10 UCs (43%) and 13 DCs (57%). Tumor cells were arranged as single cells (9 UCs, 90%; 12 DCs, 92%) and 3-dimensional groups (8 UCs, 80%; 11 DCs, 85%). Most cases showed high nuclear-to-cytoplasmic ratios. Nuclear molding was observed in 3 UCs (30%) and in 5 DCs (38%). Nuclear chromatin was often coarsely granular 6 UCs, 60%; 9 DCs, 69%). Nucleoli were inconspicuous in some cases (6 UCs, 60%; 8 DCs, 62%) but were appreciable in others. Necrosis was observed in 5 UCs (50%) and in 5 DCs (38%). Most cases exhibited clean backgrounds, and a few showed acute inflammation. Comparison of the cytologic features of UCs and DCs did not reveal any statistically significant differences.

CONCLUSIONS

UCs and DCs have a spectrum of cytomorphologic appearances that are not pathognomonic, but the presence of some of these (relatively uniform population of predominantly singly dispersed cells with high nuclear-to-cytoplasmic ratios and variably conspicuous nucleoli) should prompt consideration of UC and DC in the differential diagnosis.

Immunophenotypic features of dedifferentiated endometrial carcinoma - insights from BRG1/INI1-deficient tumours

AIMS

Dedifferentiated endometrial carcinoma (DDEC) is defined by the presence of an undifferentiated carcinoma together with an endometrioid carcinoma. Inactivation of SMARCA4 (BRG1) and inactivation of SMARCB1 (INI1) were recently described as potential mechanisms underlying the histological dedifferentiation. The aim of this study was to characterize the immunophenotypic features of DDECs, particularly in cases with prototypical histological and molecular features (BRG1/INI1 deficiency).

METHODS AND RESULTS

We evaluated PAX8, oestrogen receptor (ER) and p53 immunostaining in the endometrioid and the undifferentiated components of 20 BRG1/INI1-deficient DDECs and 15 BRG1/INI1-intact DDECs, and compared the results with those of 23 grade 3 endometrioid carcinomas. The differentiated endometrioid component was positive for PAX8 and/or ER in 19 of 20 BRG1/INI1-deficient DDECs, whereas the corresponding undifferentiated component of all 20 tumours showed a complete absence of PAX8 and ER staining. All except one of the BRG1/INI1-deficient tumours showed a wild-type p53 staining pattern. PAX8 and ER expression in the undifferentiated component was absent in 67% and 80% of BRG1/INI1-intact DDECs, respectively, whereas 47% of the BRG1/INI1-intact DDECs showed a mutated p53 staining pattern. In comparison, absent PAX8 expression and absent ER expression were each observed in the more solid area of 48% and 48% of grade 3 endometrioid carcinomas.

CONCLUSIONS

The consistent absence of PAX8 and ER expression in molecularly defined (BRG1/INI1-deficient) DDECs suggests that the loss of PAX8 and ER expression is a fundamental feature of dedifferentiation. The frequent findings of a mutated p53 staining pattern in BRG1/INI1-intact DDECs indicate that BRG1/INI1-intact DDECs may be biologically different from BRG1/INI1-deficient tumours.

Loss of switch/sucrose non-fermenting complex protein expression is associated with dedifferentiation in endometrial carcinomas

Dedifferentiated endometrial carcinoma is an aggressive type of endometrial cancer that contains a mix of low-grade endometrioid and undifferentiated carcinoma components. We performed targeted sequencing of eight dedifferentiated carcinomas and identified somatic frameshift/nonsense mutations in SMARCA4, a core ATPase of the switch/sucrose non-fermenting (SWI/SNF) complex, in the undifferentiated components of four tumors. Immunohistochemical analysis confirmed the loss of SMARCA4 in the undifferentiated component of these four SMARCA4-mutated cases, whereas the corresponding low-grade endometrioid component showed retained SMARCA4 expression. An expanded survey of other members of the SWI/SNF complex showed SMARCB1 loss in the undifferentiated component of two SMARCA4-intact tumors, and all SMARCA4- or SMARCB1-deficient tumors showed concomitant loss of expression of SMARCA2. We subsequently examined the expression of SMARCA2, SMARCA4, and SMARCB1 in an additional set of 22 centrally reviewed dedifferentiated carcinomas and 31 grade 3 endometrioid carcinomas. Combining the results from the index and the expansion set, 15 of 30 (50%) of the dedifferentiated carcinomas examined showed either concurrent SMARCA4 and SMARCA2 loss (37%) or concurrent SMARCB1 and SMARCA2 loss (13%) in the undifferentiated component. The loss of SMARCA4 or SMARCB1 was mutually exclusive. All 31 grade 3 endometrioid carcinomas showed intact expression of these core SWI/SNF proteins. The majority (73%) of the SMARCA4/SMARCA2-deficient and half of SMARCB1/SMARCA2-deficient undifferentiated component developed in a mismatch repair-deficient molecular context. The observed spatial association between SWI/SNF protein loss and histologic dedifferentiation suggests that inactivation of these core SWI/SNF proteins may contribute to the development of dedifferentiated endometrial carcinoma.

Low-grade endometrioid carcinoma of the ovary associated with undifferentiated carcinoma: case report and review of the literature

The association of low-grade endometrioid carcinoma with undifferentiated carcinoma (UC) was first reported in endometrium carcinoma, termed with dedifferentiated carcinoma (DC). However, the coexistence of low-grade endometrioid carcinoma (LGEC) or serous carcinoma (LGSC) with UC has received minimal attention in ovary, and the behavior of this kind of neoplasm remains at further discussion. In this study, we reported a case of low-grade ovarian endometrioid carcinoma associated with UC and reviewed another four cases previously reported. We found a histological continuity between the LGEC and UC components in H&E section, which suggested a dedifferentiation from LGEC to UC components. In summary, this kind of pathological type has aggressive behavior and these patients have very poor prognosis regardless of the amount of undifferentiated carcinoma.

Cytological features of dedifferentiated adenoid cystic carcinoma of the trachea: a case report

Adenoid cystic carcinoma (AdCC) is a distinct type of carcinoma, and cytological examination has been recognized as a useful tool in its diagnosis. Dedifferentiation is defined as the abrupt transformation of a low-grade tumor into a tumor with high-grade components. Albeit extremely rare, dedifferentiated AdCC has been reported: however, the cytological features of this tumor have not been documented. We observed a case in which a 66-year-old Japanese male had stenosis and thickness of the lower tracheal and bronchial walls. Cytological smears of a bronchial brush specimen revealed features typical for low-grade AdCC. However, a few cohesive epithelial cell clusters composed of large, atypical polygonal cells with large nuclei and conspicuous nucleoli also were present. This component was considered to represent dedifferentiated carcinoma. Histopathological study of the resected bronchial tumor revealed dedifferentiated AdCC. The cytological diagnosis of conventional low-grade AdCC is straightforward in most cases, although extremely rare, dedifferentiated carcinoma can occur within the conventional AdCC, and detection of a dedifferentiated component is possible in a cytological specimen because of obvious nuclear atypia. Therefore, careful observation is needed because cytologic diagnosis of dedifferentiated AdCC can help expedite treatment of this highly aggressive tumor.