Genomic profiling of multiple primary cancers including synchronous lung adenocarcinoma and bilateral malignant mesotheliomas: Identification of a novel BAP1 germline variant

Clinical practice guidelines for the diagnosis and surveillance of BAP1 tumour predisposition syndrome

BRCA1-associated protein-1 (BAP1) is a recognised tumour suppressor gene. Germline BAP1 pathogenic/likely pathogenic variants are associated with predisposition to multiple tumours, including uveal melanoma, malignant pleural and peritoneal mesothelioma, renal cell carcinoma and specific non-malignant neoplasms of the skin, as part of the autosomal dominant BAP1-tumour predisposition syndrome. The overall lifetime risk for BAP1 carriers to develop at least one BAP1-associated tumour is up to 85%, although due to ascertainment bias, current estimates of risk are likely to be overestimated. As for many rare cancer predisposition syndromes, there is limited scientific evidence to support the utility of surveillance and, therefore, management recommendations for BAP1 carriers are based on expert opinion. To date, European recommendations for BAP1 carriers have not been published but are necessary due to the emerging phenotype of this recently described syndrome and increased identification of BAP1 carriers via large gene panels or tumour sequencing. To address this, the Clinical Guideline Working Group of the CanGene-CanVar project in the United Kingdom invited European collaborators to collaborate to develop guidelines to harmonize surveillance programmes within Europe. Recommendations with respect to BAP1 testing and surveillance were achieved following literature review and Delphi survey completed by a core group and an extended expert group of 34 European specialists including Geneticists, Ophthalmologists, Oncologists, Dermatologists and Pathologists. It is recognised that these largely evidence-based but pragmatic recommendations will evolve over time as further data from research collaborations informs the phenotypic spectrum and surveillance outcomes.

Second Primary Cancers in a Population-Based Mesothelioma Registry

Background: The presence of a second primary cancer (SPC) in patients with pleural mesothelioma (PM) may impact overall survival and suggest a common mechanism of carcinogenesis or an underlying germline genetic alteration. Methods: We evaluated the occurrence of SPCs within PM cases collected from 2000 to 2018 by the Lombardy Mesothelioma Registry and their prognostic implications. Kaplan–Meier analysis was performed to estimate median survival times, together with univariate and multivariate Cox regression models to estimate hazard ratios (HR) and 95% confidence intervals (CI) of death. Results: The median overall survival (OS) of the entire study population (N = 6646) was 10.9 months (95% CI: 10.4–11.2); patient age and histotype were the strongest prognostic factors. No substantial survival difference was observed by the presence of an SPC (10.5 months in 1000 patients with an SPC vs. 10.9 months in 5646 patients in the non-SPC group, HR 1.03, p = 0.40). Shorter OS in the SPC group was only observed in 150 patients with the non-epithelioid subtype (median OS of 5.4 vs. 7.1 months, HR 1.21, p = 0.03). Conclusions: The diagnosis of an SPC did not influence the outcome of PM patients in the overall study population but was associated with shorter OS in non-epithelioid cases. Further studies are needed to clarify the role of SPCs as markers of genetic susceptibility in mesothelioma.

Diagnostics of BAP1-Tumor Predisposition Syndrome by a Multitesting Approach: A Ten-Year-Long Experience

Germline mutations in the tumor suppressor gene BRCA1-associated protein-1 (BAP1) lead to BAP1 tumor predisposition syndrome (BAP1-TPDS), characterized by high susceptibility to several tumor types, chiefly melanoma, mesothelioma, renal cell carcinoma, and basal cell carcinoma. Here, we present the results of our ten-year experience in the molecular diagnosis of BAP1-TPDS, along with a clinical update and cascade genetic testing of previously reported BAP1-TPDS patients and their relatives. Specifically, we sequenced germline DNA samples from 101 individuals with suspected BAP1-TPDS and validated pathogenic variants (PVs) by assessing BAP1 somatic loss in matching tumor specimens. Overall, we identified seven patients (7/101, 6.9%) carrying six different germline BAP1 PVs, including one novel variant. Consistently, cascade testing revealed a total of seven BAP1 PV carriers. In addition, we explored the mutational burden of BAP1-TPDS tumors by targeted next-generation sequencing. Lastly, we found that certain tumors present in PV carriers retain a wild-type BAP1 allele, suggesting a sporadic origin of these tumors or a functional role of heterozygous BAP1 in neoplastic development. Altogether, our findings have important clinical implications for therapeutic response of BAP1-TPDS patients.

Application Value of PET/CT and MRI in the Diagnosis and Treatment of Patients With Synchronous Multiple Pulmonary Ground-Glass Nodules

Background

Synchronous multiple ground-glass nodules (SMGGNs) in synchronous multiple lung cancers are associated with specific imaging findings. It is difficult to distinguish whether multiple nodules are primary tumors or metastatic lesions in the lungs. The need for PET/CT and contrast-enhanced brain MRI for these patients remains unclear. This study investigated the necessity of these two imaging examinations for SMGGN patients by means of retrospective analysis.

Methods

SMGGN patients who were diagnosed and treated in our hospital from October 2017 to May 2020 and underwent whole-body PET/CT(Cranial excepted) and/or contrast-enhanced brain MRI+DWI were enrolled in this study. We analyzed the imaging and clinical characteristics of these patients to evaluate SMGGN patients’ need to undergo whole-body PET/CT and brain MRI examination.

Results

A total of 87 SMGGN patients were enrolled. 51 patients underwent whole-body PET/CT examinations and did not show signs of primary tumors in other organs, metastatic foci in other organs, or metastasis to surrounding lymph nodes. 87 patients underwent whole-brain MRI, which did not reveal brain metastases but did detect an old cerebral infarction in 23 patients and a new cerebral infarction in one patient. 87 patients underwent surgical treatment in which 219 nodules were removed. All nodules were diagnosed as adenocarcinoma or atypical adenomatous hyperplasia. No lymph node metastasis was noted.

Conclusion

For SMGGN patients, PET/CT and enhanced cranial MRI are unnecessary for SMGGNs patients, but from the perspective of perioperative patient safety, preoperative MRI+DWI examination is recommended for SMGGNs patients.

Malignant pleural mesothelioma showing rare morphology indistinguishable from myxofibrosarcoma concomitant with EGFR-mutated lung adenocarcinoma: A case report

Introduction and importance

Primary tumors of the pleura are rare, with malignant mesothelioma being the most common of these neoplasms. Pathological diagnosis of sarcomatoid mesothelioma can be more challenging than that of epithelioid malignant mesothelioma because of its similarities with true sarcomas and restricted or inconsistent expression of mesothelial markers in immunohistochemistry analysis.

Presentation of case

Here, we present an unusual case of malignant pleural mesothelioma concomitant with lung adenocarcinoma in a 72-year-old Japanese man, a smoker with no family history of cancer and asbestos exposure. Malignant pleural mesothelioma is composed of epithelial and spindle-shaped cells. Spindle-shaped cells with scant eosinophilic cytoplasm and hyperchromatic nuclei proliferated in abundant myxoid stroma containing thin-walled blood vessels, mimicking myxofibrosarcoma. The loss of BAP1 (BRCA1-associated protein 1) expression, as assessed by immunohistochemistry, and homozygous deletions of CDKN2A, detected using fluorescence in situ hybridization (FISH), were observed in both components. Targeted sequencing revealed that lung adenocarcinoma harbored EGFR mutations, whereas no mutations were detected in either component of biphasic mesothelioma.

Discussion

Although alcian blue-stained mucins were detected in biphasic mesothelioma subsets, the clinicopathological significance of myxoid stroma in biphasic and sarcomatoid mesothelioma remains largely unknown.

Conclusion

Our case presented a unique morphology mimicking myxofibrosarcoma in a sarcomatoid component of biphasic mesothelioma; therefore, it raises a question on the clinicopathological significance of myxoid stroma in sarcomatous areas of biphasic and sarcomatoid mesothelioma.

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A case of concomitant pleural mesothelioma and lung adenocarcinoma.

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Biphasic mesothelioma had areas mimicking myxofibrosarcoma.

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The loss of BAP1 expression was assessed by immunohistochemistry.

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Homozygous deletions of CDKN2A was detected by FISH.

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Lung adenocarcinoma harbored EGFR mutation.

HNF-1β is a More Sensitive and Specific Marker Than C-Reactive Protein for Identifying Biliary Differentiation in Primary Hepatic Carcinomas

CONTEXT.—

Intrahepatic cholangiocarcinoma (iCCA) needs to be distinguished from hepatocellular carcinoma (HCC) and metastasis, and in the absence of any specific biliary markers, is often a diagnosis of exclusion. Hepatocyte nuclear factor (HNF)-1β is a transcription factor that plays a critical role in bile duct system morphogenesis.

OBJECTIVE.—

To investigate the diagnostic value of HNF-1β to differentiate iCCA from HCC by immunohistochemistry and compare HNF-1β with C-reactive protein (CRP), a previously identified marker for iCCA.

DESIGN.—

Cases of iCCA (n = 75), combined hepatocellular-cholangiocarcinoma (cHCC-CCA) (n = 13) and HCC (n = 65) were included in the study.

RESULTS.—

All cases of iCCA (74 of 74, 100%) expressed HNF-1β compared with CRP expressed in 72.60% (53 of 73). The sensitivity and specificity of HNF-1β to differentiate iCCA from HCC was 100% and 92.31%, whereas the sensitivity and specificity for CRP was 75.58% and 7.79%. The expression of HNF-1β was greater in iCCA and the CCA component of cHCC-CCA compared with CRP (87 of 87, 100% versus 65 of 86, 75.58%, P < .001). On the contrary, CRP was more frequently expressed compared with HNF-1β in HCC and HCC component of cHCC-CCA (71 of 77, 92.21% versus 6 of 78, 7.69%; P < .001).

CONCLUSIONS.—

Our data indicate that HNF-1β is a more sensitive and specific marker than CRP for the diagnosis of iCCA and to identify the CCA component in cHCC-CCA. Lack of HNF-1β expression may be used to exclude iCCA from consideration in cases of adenocarcinomas of unknown primary.