Characterization of a Molecularly Distinct Subset of Oncocytic Pleomorphic Adenomas/Myoepitheliomas Harboring Recurrent ZBTB47-AS1::PLAG1 Gene Fusion

Recurrent gene fusions are common in salivary gland tumors including benign tumors, such as pleomorphic adenoma (PA) and myoepithelioma (ME). In cases where chromosomal rearrangement is identified in the pleomorphic adenoma gene 1 (PLAG1) gene, different gene partners are found. Oncocytic metaplasia, characterized by oncocytes with abundant eosinophilic granular cytoplasm and hyperchromatic nuclei, is a well-known phenomenon in salivary gland neoplasms. However, the pure oncocytic variant of PA/ME showed PLAG1 gene rearrangements involving various gene partners at the molecular level, without any recurrent fusion being found. Our study includes 20 cases of PA/ME, with 11 females and 9 males. The age of patients ranged from 37 to 96 years, with a median age of 62.8 years. Most tumors originate from the parotid gland. The median size of the tumor was 26.5 mm (range: 13 to 60 mm). Among the 20 cases, 14 were a pure oncocytic variant of PA/ME, whereas 6 cases showed focal oncocytic or oncocytic-like aspects. Molecular studies on 20 cases of PA/ME were conducted. A novel recurrent ZBTB47-AS1::PLAG1 fusion was identified in 6 of 12 cases with pure oncocytic metaplasia, whereas the other cases had PLAG1 gene fusion with different gene partners. The transcriptomic analysis of the cases harboring ZBTB47-AS1::PLAG1 fusion demonstrated that these tumors have a distinct molecular profile from conventional PA/ME. This study reveals a unique subset in the oncocytic PA/ME spectrum characterized by pure oncocytic morphology with larger oncocytic cells and recurrent ZBTB47-AS1::PLAG1 fusion. It also highlights the transcriptomic distinctness of salivary gland adenomas with pure oncocytic metaplasia in the spectrum of salivary gland neoplasms. Further studies are needed to better understand the oncocytic variant of PA/ME and to determine the true nature of oncocytic cells in PA/ME.

Management of 80 sinonasal undifferentiated carcinomas. Retrospective multicentre study of the French Network of Rare Head and Neck Cancers (REFCOR)

OBJECTIVES

Sinonasal undifferentiated carcinoma (SNUC) is a rare and aggressive disease requiring multimodal treatment, and multiple new entities once included in the spectrum of SNUC, such as SWI/SNF-deficient carcinomas, are emerging. We aimed to provide new data regarding the role of chemotherapy and surgery and the prognostic factors of disease-free survival.

METHODS

This study was based on data from the REFCOR database and included patients with SNUC treated with curative intent from 2007 to 2021 across 22 centres in France.

RESULTS

A total of 80 patients were included in the analysis. Among the entire cohort, the 5-year disease-free survival (DFS) and overall survival (OS) rates were 58% and 63%, respectively. Of 100% of the patients treated with irradiation, 29% underwent surgery, 56% neoadjuvant chemotherapy (82% had either a partial or a complete response) and 76% chemoradiotherapy. No treatment modality was associated with a better OS or DFS, including surgery (p = 0.34). There was a trend for a better DFS for the patients treated with chemotherapy (neoadjuvant or concomitant, p = 0.062). Overall survival at 3 years was 58% for SWI/SNF deficient group and 86% for non deficient group (p = 0.14). The locoregional relapse rate without distant metastases was 21% in the exclusive radiotherapy group and 26% in the surgery group. Grade 3 or higher toxicities concerned 9%, 32% and 29% of patients for surgery, radiotherapy and chemotherapy respectively.

CONCLUSION

In the management of localised SNUC among all patients treated with irradiation, surgery yielded no benefit, whereas the addition of chemotherapy tended to improve disease-free survival.

Dilated odontoma: an unusual case report and literature review

Introduction: Dilated odontoma is the most severe form of a dens invaginatus, which is a rare dental malformation resulting from an invagination of the enamel organ into the dental papilla before calcification occurs. Observation: A healthy 7-years-old girl was referred to the oral surgery department to remove an impacted odontoma causing a delayed dental eruption of the right mandibular lateral incisor (tooth 42). The patient was painless and a lingual osseous swelling was observed. A computed tomography and a 3D segmentation revealed a shell-shaped mass in the position of the right mandibular lateral incisor, showing a complex anatomy. Surgical excision was carried out under general anesthesia. Histological analysis confirmed the diagnosis of DO. Discussion and conclusion: We performed a literature review investigating 16 cases of severe forms of dens invaginatus which required extraction. It highlighted the atypical aspect of our case and the importance of 3D imaging and segmentation in contributing to the accurate diagnosis and treatment of this dental malformation.

ASS1 Overexpression: A Hallmark of Sonic Hedgehog Hepatocellular Adenomas; Recommendations for Clinical Practice

Until recently, 10% of hepatocellular adenomas (HCAs) remained unclassified (UHCA). Among the UHCAs, the sonic hedgehog HCA (shHCA) was defined by focal deletions that fuse the promoter of Inhibin beta E chain with GLI1. Prostaglandin D2 synthase was proposed as immunomarker. In parallel, our previous work using proteomic analysis showed that most UHCAs constitute a homogeneous subtype associated with overexpression of argininosuccinate synthase (ASS1). To clarify the use of ASS1 in the HCA classification and avoid misinterpretations of the immunohistochemical staining, the aims of this work were to study (1) the link between shHCA and ASS1 overexpression and (2) the clinical relevance of ASS1 overexpression for diagnosis. Molecular, proteomic, and immunohistochemical analyses were performed in UHCA cases of the Bordeaux series. The clinico‐pathological features, including ASS1 immunohistochemical labeling, were analyzed on a large international series of 67 cases. ASS1 overexpression and the shHCA subgroup were superimposed in 15 cases studied by molecular analysis, establishing ASS1 overexpression as a hallmark of shHCA. Moreover, the ASS1 immunomarker was better than prostaglandin D2 synthase and only found positive in 7 of 22 shHCAs. Of the 67 UHCA cases, 58 (85.3%) overexpressed ASS1, four cases were ASS1 negative, and in five cases ASS1 was noncontributory. Proteomic analysis performed in the case of doubtful interpretation of ASS1 overexpression, especially on biopsies, can be a support to interpret such cases. ASS1 overexpression is a specific hallmark of shHCA known to be at high risk of bleeding. Therefore, ASS1 is an additional tool for HCA classification and clinical diagnosis.

Snapshot summary of diagnosis and management of hepatocellular adenoma subtypes

Hepatocellular adenomas (HCA) are rare benign hepatocellular tumors occurring mainly in women taking oral contraceptives with 2 major complications: severe bleeding and malignant transformation that can be avoided if nodules exceeding 5 cm are resected. This simple attitude has been challenged in the recent years with HCA in men, in young adolescent, in aged persons, and complications in hepatocellular adenomas below 5 cm. The discovery of specific mutations leading to specific phenotypes has modified the clinical spectrum of the disease. The phenotypic immune classification of HCA based on the molecular classification is being widely used in liver referral centers. The aim of this snapshot is to briefly present for each subtype the clinical, pathological, immuno-pathological criteria as well as the risk of complications and guidelines for treatment and management.

Mandibular exostosis following an epithelial–conjunctival graft: a case report

Observation: A 68-year-old patient presented to us because of the gradual onset of symptoms associated with a mass located on an epithelial–mucosal graft performed approximately 20 years ago. A provisional diagnosis of exostosis was made and the mass was excised under local anesthesia. Comments: Exostosis is defined as a localized benign bone proliferation constituting a sessile nodular bony outgrowth with either a broad base or a peduncle attaching to the parent bone. Some cases of exostosis secondary to the realization of gingival grafts have been reported in the literature. Thus, exostosis should be considered as an unpredictable side effect of this surgical procedure.

Unexpected discovery of small HNF1α-inactivated hepatocellular adenoma in pathological specimens from patients resected for liver tumours

BACKGROUND AND AIMS

It is rare but not uncommon to discover micro/small HNF1α-inactivated hepatocellular adenoma (H-HCA) outside the context of resected H-HCA. We aimed to review our cases of micro/small H-HCA discovered by chance on different kinds of liver resected specimens.

METHODS

We retrieved cases of micro/small H-HCA discovered by chance on resected specimens outside the context of H-HCA. All these nodules were liver fatty acid binding protein (LFABP)-negative contrasting with normal positivity in the surrounding non-tumoural liver, ruling out the possibility of focal steatosis or other subtypes of micro-HCAs.

RESULTS

We identified 19 micro/small H-HCA cases. In 16 cases they were discovered in patients who underwent surgery for benign nodules including one haemangioma, six focal nodular hyperplasia, seven inflammatory HCA (including one with b-catenin activation), one HCA, whose subtype could not be identified because of massive necrosis/hemorrhage, and one hepatocellular carcinoma. In two additional cases, patients followed up for a melanoma underwent liver surgery to remove micro nodules possibly related to a metastatic process. Finally in one case a micro nodule was seen and resected during a cholecystectomy.

CONCLUSION

Taken together, H-HCAs are more frequent than we initially supposed as micro and small HCAs cannot all be detected by routine ultrasound. Despite no information on the potential growth of these micro/small H-HCAs, there is no argument to stop oral contraceptives or to ask for a specific regular surveillance. The association of different subtypes of HCAs with focal nodular hyperplasia suggests they share or have common etiological factors.

Focal β-catenin mutation identified on formalin-fixed and paraffin-embedded inflammatory hepatocellular adenomas

The identification of hepatocellular adenoma (HCA) with mutation in exon 3 of the CTNNB1 gene encoding for β-catenin is clinically relevant due to a higher risk of malignant transformation. Inflammatory HCA (IHCA) can exhibit β-catenin activation (β-IHCA). We report two cases with multiple IHCA in which focal β-catenin activation has been found in one of the IHCA. In both cases, the diagnosis of IHCA was confirmed on the resected nodules by routine stains, immunohistochemical detection of C-reactive protein (CRP) and molecular biology on frozen material. An additional molecular analysis was performed on formalin-fixed paraffin-embedded (FFPE) material that showed focal glutamine synthetase (GS) staining, the surrogate marker of β-catenin activation. In case 1, it was a 1.8-cm area within the 7.5 cm IHCA, and in case 2 a small 0.3-cm area within a 1.8 cm resected IHCA located close to a larger IHCA, negative for GS. In both cases, nuclear β-catenin expression and decreased reticulin network were observed in the GS expressing foci, together with cholestasis and diffuse CD34 expression in case 1. Molecular analysis by pyrosequencing on FFPE material using the GS-stained slides as reference to select areas with/without positive staining revealed a CTNNB1 exon 3 mutation restricted to the areas exhibiting both positive GS and CRP expression, whereas wild-type CTNNB1 was found in areas showing only CRP staining. These two cases illustrate focal β-catenin activation that can occur within IHCAs. Additional data are needed to determine if β-catenin mutation is a secondary event in IHCA.

Fatal Acute Liver Failure as a Consequence of Regorafenib Treatment in a Metastatic Colon Cancer

Regorafenib is a multikinase inhibitor which showed benefits in pretreated metastatic colorectal cancer patients. Hepatotoxicity has been described as a frequent side effect. We report the case of a 65-year-old patient presenting with jaundice, fever, and hepatocellular insufficiency which led to death of the patient. She had previously been treated with several lines of chemotherapy for sub- and diaphragmatic ganglionic metastases of a colon adenocarcinoma. There were no liver metastases. The fatal liver failure occurred at the beginning of treatment with regorafenib at a dosage of 3 tablets per day. No concomitant treatment was given, and other causes of liver damage were eliminated. The liver biopsy showed hepatocyte necrosis with lymphocyte infiltration. This observation illustrates the risk of severe hepatic involvement typically occurring within the first 2 months of treatment. Monitoring liver biology every 2 weeks is essential during the first 2 months to detect any hepatotoxicity.

Steatotic hepatocellular adenomas with different phenotypic subtypes: a case report

Hepatocellular adenomas (HCAs) are heterogeneous group of benign tumors; three pathomolecular subtypes have been identified so far: hepatocyte nuclear factor 1 α-inactivated HCA (H-HCA) (35-40%), inflammatory HCA (I-HCA) (>50%), β-catenin activated HCA (10%). Ten percent of I-HCA are also β-catenin activated. We report a rare case of three histologically confirmed steatotic HCAs of three different phenotypes: I-HCA, β-catenin activated I-HCA, and H-HCA in a 36-year-old woman. This observation outlines that in the same patient, HCA may be of different subtypes. The predisposition to develop different HCA hypothetically caused by a "benign tumorigenic field effect" may result, even rarely, in different genotypes/phenotypes such as H-HCA and I-HCA. Moreover, we illustrate the very high specificity of MR for subtyping HCA.

BRAF V600E mutational status in bile duct adenomas and hamartomas

AIMS

Bile duct adenomas (BDA) and bile duct hamartomas (BDH) are benign bile duct lesions considered neoplastic or secondary to ductal plate malformation, respectively. We have reported previously a high prevalence of BRAF V600E mutations detected by allele-specific polymerase chain reaction assay in BDA, and suggested that BDA may be precursors to a subset of intrahepatic cholangiocarcinomas harbouring V600E mutations. The aim of the present study was to assess the existence of BRAF V600E mutations, using immunohistochemical methods, in additional BDA as well as in BDH.

METHODS AND RESULTS

Fifteen BDA and 35 BDH were retrieved from the archives of the pathology departments of two French university hospitals. All cases were reviewed by two pathologists specialized in liver diseases. BRAF V600E mutational status was investigated by immunohistochemistry. Mutated BRAF mutant protein was detected in 53% of the BDA and in none of the cases of BDH.

CONCLUSION

Our findings suggest that BDA and BDH are different processes, and that BDA represent true benign neoplasms. They also support the hypothesis that mutated BDA might precede the development of the subset of intrahepatic cholangiocarcinomas harbouring BRAF V600E mutations.

[Incidental intraplacental gestational choriocarcinoma on a full-term placenta]

Of all the gestational trophoblastic tumors, the gestational choriocarcinomas have the worst prognosis and the most uncommon. We report a case diagnosed on a full-term placenta, discovered incidentally. The patient, gravida 2, para 1, delivered a hypotrophic infant at 38 weeks gestation. The placenta was examined in the laboratory to perform anatomo-pathological examination in order to explain the growth retardation. This study revealed the presence of an intraplacental choriocarcinoma. Disease staging was negative for both mother and child, and beta-HCG levels remained at zero. These two factors are rather good prognosis for choriocarcinoma. With this observation, we highlight the added-value of placental examination, which seems essential for any fetal pathology, pathological pregnancy and intrapartum complications. Anatomo-pathological examination must be meticulous and systematized in order to not overlook an intraplacental tumor.