RF09 | PSUN29 Evidence for a Founder Effect of SDHB Exon 1 Complete Deletion in Brazilian Patients with Paraganglioma

Background

Pheochromocytomas and paragangliomas (PPGLs) have the highest degree of heritability among endocrine tumors. Currently, ∼40% of PPGL individuals have a genetic germline pathogenic variant and exist at least 12 different genetic syndromes related to these tumors. Pathogenic variants in the Succinate Dehydrogenase Complex Subunit B (SDHB) gene account for about 10% of PPGL cases. Moreover, SDHB pathogenic variants are the most well-established risk factor to predict metastatic disease (40%-50% of cases). Germline SDHB large deletions are very rare worldwide, but SDHB exon 1 deletion has been reported in patients with PPGLs from Portugal and Spain. Indeed, a putative founder effect for SDHB exon 1 deletion was suggested in PPGL patients from Iberian Peninsula.

Aim

To investigate a putative founder effect for SDHB exon 1 deletion.

Methods

Eighteen unrelated Brazilian patients with germline heterozygous SDHB pathogenic variants were included. Additionally, two unrelated individuals with SDHB exon 1 complete deletion from Argentina were studied. SDHB pathogenic variants were investigated by automated SAGER sequencing, multiplex ligation-dependent probe amplification (SALSA MLPA Probemix P226 SDH) and/or high-throughput sequencing. Five SDHB flanking microsatellite markers at chromosome 1p (D1S2697, GATA29A05, D1S2826, D1S2644, and D1S199) were used to investigate if patients carrying this deletion have a common origin. Haplotypes were reconstructed using the PHASE algorithm (v. 2.1). A control group comprising 26 unrelated Brazilian individuals was also studied.

Results

Among 18 Brazilian patients with germline SDHB pathogenic variants, heterozygous SDHB exon 1 complete deletion was identified in 6 of them (33% of the cases). The remaining 12 patients presented intragenic SDHB pathogenic variants without hotspot location. All Brazilian index patients with SDHB exon 1 deletion presented with paraganglioma, located mostly in the abdomen (4 abdominal; one thoracic; two head and neck and one colonic). Median age was 31.5 years and metastatic disease occurred in 3 (50%) of them. Haplotype analysis showed that 4 apparently unrelated Brazilian patients (4 out of 6 cases, 67%) shared a common allele (SDHB-GATA29A05-D1S2826-D1S2644-D1S199 | SDHB-186-130-213-102), which was not seen in chromosomes without the SDHB exon 1 deletion (p= 0.01). The two cases from Argentina did not have this haplotype, suggesting that SDHB exon 1 deletion in Argentina have a different origin.

Conclusion

SDHB exon 1 complete deletion was the most frequent SDHB defect in our cohort. Our findings indicate a founder effect for SDHB exon 1 complete deletion in Brazilian patients with paraganglioma.

Support: Sao Paulo Research Foundation (FAPESP) grant 2019/15873-6

Presentation: Saturday, June 11, 2022 1:24 p.m. - 1:29 p.m., Sunday, June 12, 2022 12:30 p.m. - 2:30 p.m.

Genetic and clinical aspects of paediatric pheochromocytomas and paragangliomas

OBJECTIVE

Few and conflicting reports have characterized the genetics of paediatric pheochromocytomas and paragangliomas (PPGLs). This study aimed to investigate the clinical and genetic features of Brazilian children with PPGL.

PATIENTS AND METHODS

This study included 25 children (52% girls) with PPGL. The median age at diagnosis was 15 years (4-19). The median time of follow-up was 145 months. The genetic investigation was performed by Sanger DNA sequencing, multiplex ligation-dependent probe amplification and/or target next-generation sequencing panel.

RESULTS

Of the 25 children with PPGL, 11 (44%), 4 (16%), 2 (8%), 1 (4%) and 7 (28%) had germline VHL pathogenic variants, SDHB, SDHD, RET and negative genetic investigation, respectively. Children with germline VHL missense pathogenic variants were younger than those with SDHB or SDHD genetic defects [median (range), 12 (4-16) vs. 15.5 (14-19) years; P = .027]. Moreover, 10 of 11 cases with VHL pathogenic variants had bilateral pheochromocytoma (six asynchronous and four synchronous). All children with germline SDHB pathogenic variants presented with abdominal paraganglioma (one of them malignant). The two cases with SDHD pathogenic variants presented with head and neck paraganglioma. Among the cases without a genetic diagnosis, 6 and 2 had pheochromocytoma and paraganglioma, respectively. Furthermore, metastatic PPGL was diagnosed in four (16%) of 25 PPGL.

CONCLUSIONS

Most of the paediatric PPGL were hereditary and multifocal. The majority of the affected genes belong to pseudohypoxic cluster 1, with VHL being the most frequently mutated. Therefore, our findings impact surgical management and surveillance of children with PPGL.

MON-202 Germline SDHB Exon 1 Deletion Is Associated with Absence of 131I-metaiodobenzylguanidine (MIBG) Uptake in Malignant Paragangliomas

Introduction: Pheochromocytomas and paragangliomas (PPGLs) are rare neuroendocrine tumors arising from chromaffin cells. More than 30% of patients with PPGLs have a hereditary predisposition. Malignancy in PPGLs is defined by the presence of local invasion or metastasis in nonchromaffin tissues. Germline SDHB mutations are found in approximately 40% of malignant PPGLs, mainly paragangliomas (PGLs). However, SDHB mutations are not a prognostic factor in malignant PPGLs. To date, no genotype-phenotype correlation has been reported in malignant PPGLs associated with SDHB mutations. Aim: To investigate clinical and imaging features of patients with malignant PGLs harboring germline SDHB exon 1 deletion or splicing site mutation. Methods: We retrospectively evaluated 22 unrelated individuals with malignant PPGLs. Six out of 22 (27%) malignant PPGLs harbored germline SDHB mutations. Three patients had SDHB exon 1 deletion and 3 splicing site mutation (2 with c.201-2A>G and one with c.423 + 1G>A). All SDHB defects were classified as likely pathogenic. Results: In the exon 1 deletion group, 2 patients had abdominal PGLs (one also had a neck PGL) and one had only head and neck PGLs. In the splicing site mutation group, all 3 patients had abdominal PGLs (one also had a neck PGL). Median age at diagnosis was 26 yrs (16 to 45) and 33 yrs (26 to 53) in the exon 1 deletion and splicing mutation groups, respectively. Two patients (one in each group) had metastasis at diagnosis. All 6 patients had bone metastasis, but liver and/or lung metastasis were more frequent in patients with SDHB exon 1 deletion (66 vs. 33%). Interestingly, metastasis from malignant PGLs harboring SDHB splicing site mutations were ¹³¹I-metaiodobenzylguanidine (MIBG) avid in all cases, whereas metastatic lesions from malignant PGLs harboring SDHB exon 1 deletion did not present any MIBG uptake on diagnostic imaging studies. Therefore, all 3 patients with SDHB exon 1 deletion were treated with chemotherapy (cyclophosphamide, vincristine and dacarbazine). In contrast, all 3 patients with splicing site mutations have been treated with MIBG therapy. Median follow-up was 87 months (8 to 360 months). Only one patient (exon 1deletion group) died because of disease progression. Conclusion: We first demonstrated here that germline SDHB exon 1 deletion is associated with absence of MIBG uptake in malignant PGLs. This finding needs to be confirmed in an expanded cohort of malignant PPGLs.

MON-218 Clinical and Genetic Aspects of Pediatric Pheochromocytomas and Paragangliomas

Pheochromocytomas and paragangliomas (PPGLs) are neuroendocrine tumors derived from chromaffin cells. At least 30% of PPGL patients have hereditary predisposition. PPGLs in children are more often hereditary, multiple and extra-adrenal. To date, more than 14 tumor-susceptibility genes have been reported: Cluster 1 or hypoxic (VHL, SDHB, SDHD, SDHC, SDHA, SDHAF2, FH, ENGL1 and HIF2A) and cluster 2 (RET, NF1, TMEM127 and MAX). The aim of this study was to evaluate clinical and molecular aspects of a Brazilian cohort of pediatric patients with PPGLs. Out of 262 patients with PPGLs, 26 (9 %) were diagnosed before 19 yrs of age (16 males and 10 females), with a median age of 14.5 yrs (range, 4 to 18). Genetic investigation was performed in 19 patients: 14 by automated Sanger sequencing (VHL, SDHB, SDHD and RET genes) and 5 by a custom next-generation sequencing (NGS) panel including all genes previously associated with germline mutations in PPGLs. Median tumor size was 5.5 cm (1.7 to 16). Pheochromocytomas (PHEOs), paragangliomas (PGLs) or both were diagnosed in 46%, 31% and 23% of the patients, respectively. Bilateral PHEOs were diagnosed in 61% of the cases, most of them asynchronous (75%). Genetic diagnosis was confirmed in 14 out of 19 (74%) patients and all variants were found in heterozygous state: 8 VHL missense mutations from 6 kindreds (p.R167W in 2 kindreds, p.R167Q in one and p.G114S in 3); 3 SDHB mutations (p.C98Y, c.201-2A>G and p.L180L); 2 SDHD mutations (p.Y144_H145del and p.Q121*); and one RET mutation (p.C634R). All 8 VHL patients had bilateral PHEOs and 3 of them had also abdominal PGLs. All patients with SDHB mutations had abdominal PGLs. Two patients with SDHD mutation had head and neck paraganglioma (one of them had unilateral PHEO). Genetic investigation by NGS Panel was negative in all 5 cases: 2 malignant PPGLs (one PHEO and one PGL) and 3 PHEOs. Four out of 26 (15%) pediatric PPGLs were malignant: 2 with SDHB mutation and 2 with negative screening (one PHEO and one PGL). In conclusion, the majority of pediatric PPGLs (74%) were hereditary and almost exclusively caused by mutations in hypoxic genes. VHL (PHEOs) and SDHB (only PGLs) were the most frequent affected genes in this cohort of pediatric PPGLs. Support: CAPES grant to Petenuci J.

New Insights Into Pheochromocytoma Surveillance of Young Patients With VHL Missense Mutations

Context

Von Hippel-Lindau (VHL) disease is an autosomal dominant syndrome caused by germline mutations in the VHL gene. Guidelines recommend pheochromocytoma (PHEO) biochemical screening should start at age 5 years.

Objective

Genotype–phenotype correlations in VHL, focusing on PHEO penetrance in children, were studied.

Design

We retrospectively evaluated 31 individuals (median age at diagnosis was 26 years) with diagnosed VHL disease.

Results

PHEO was diagnosed in six children with VHL. A large PHEO (5 cm) was detected in a 4-year-old boy with p.Gly114Ser mutation. PHEO penetrance was 55% starting at age 4 years. VHL missense mutations were identified in 11 of 22 families (50%), frameshift mutations in four (18.2%), stop codon in three (13.6%), splicing site in two (9.1%), and large gene deletion in two (9.1%). The codon 167 (n = 10) was a hotspot for VHL mutations and was significantly associated with PHEO (90% vs. 38%; P = 0.007). PHEOs and pancreatic neuroendocrine tumors (PNETs) were strongly associated with VHL missense mutations compared with other mutations (89.5% vs. 0% and 73.7% vs. 16.7%; P = 0.0001 and 0.002, respectively). In contrast, pancreatic cysts (91.7% vs. 26.3%; P = 0.0001), renal cysts (66.7% vs. 26.3%; P = 0.027), and central nervous system hemangioblastomas (91.7% vs. 47.3%; P = 0.012) were more frequent in VHL with nonmissense mutations.

Conclusion

VHL missense mutations were highly associated with PHEO and PNETs. Our data support that in children with VHL harboring missense mutations, biochemical screening for PHEO should be initiated at diagnosis.

Response to Chemotherapy and Prognosis in Metastatic Colorectal Cancer With DNA Deficient Mismatch Repair

BACKGROUND

DNA deficient mismatch repair (dMMR) genes are associated with microsatellite instability and good prognosis in early-stage colorectal cancer (CRC). However dMMR is rare in metastatic CRC (mCRC) and little is known about its influence on treatment response rate (RR). The primary objective of this study was to compare the RR of patients with mCRC according to dMMR status.

METHODS

This was a retrospective study that compared the RR by Response Evaluation Criteria In Solid Tumors 1.1 criteria in patients with mCRC treated with chemotherapy according to dMMR status. All digital images were retrieved for RR evaluation by a single radiologist blinded to dMMR results. dMMR was defined as loss of immunohistochemistry expression of at least 1 of the MMR genes (MLH1, MSH2, MSH6, or PMS2). Cases were dMMR patients, and controls were proficient MMR (pMMR) patients (1:2 fashion). Based on clinical and molecular features, dMMR patients were classified as probable Lynch or sporadic.

RESULTS

From January 2009 to January 2013, 762 out of 1270 patients were eligible and screened for dMMR: n = 27 (3.5%) had dMMR mCRC and n = 735 (96.5%) had pMMR mCRC. Given the rarity, 14 dMMR cases outside the inclusion period were included (total 41 dMMR cases) and 84 controls (pMMR). By intention-to-treat analysis, considering all patients who received at least 1 dose of oxaliplatin-based chemotherapy (N dMMR = 34), those with dMMR had lower RR compared with those with pMMR (RR, 11.7% vs. 28.6%; odds ratio, 0.33; 95% confidence interval, 0.08-1.40; P = .088); patients with probable Lynch-related mCRC presented higher RR than subjects with probable sporadic dMMR (22.2% vs. 0%). dMMR was associated with BRAF mutations and poor prognosis, particularly in the sporadic subgroup (median survival, 29.8 vs. 5.9 months; P = .025).

CONCLUSION

This study suggests that the dMMR phenotype is predictive of resistance to oxaliplatin-based chemotherapy. Apparently, such resistance is more pronounced in the sporadic dMMR phenotype, suggesting biological heterogeneity within the dMMR mCRC subgroup.

Pulmonary nodules: a challenging diagnosis during the follow up of cancer patients

Pulmonary nodules (PN), frequently found on imaging studies, represent a diagnostic challenge during the follow up of cancer patients. However, published data about investigation of PNs incidentally found on chest imaging is scarce. The PN may be present at the time of cancer diagnosis, or arise during the treatment or follow-up periods. In the context of the oncologic patient these lesions are quite invariably considered as metastases, what impacts directly on patients´ treatment and prognosis. The present study reports 2 cases of pulmonary nodules found in two patients already diagnosed with cancer. Case 1 referred to a woman with squamous cell carcinoma and two pulmonary nodules, and in case 2 the patient was diagnosed with duodenal adenocarcinoma. Both patients were submitted to pulmonary biopsies before the oncologic treatment. In both cases the nodules were of infectious origin, what changed significantly the neoplasia staging and the oncologic treatment intention. The authors performed a literature review as well as a discussion about the management of PN in cancer patients.

Dynamics of chromosomal evolution in the genus Hypsiboas (Anura: Hylidae)

Hylidae is one of the most species-rich families of anurans, and 40% of representatives in this group occur in Brazil. In spite of such remarkable diversity, little is known about this family and its taxonomical and systematic features. Most hylids have 2n = 24, even though most of the cytogenetic data are mainly obtained based on the conventional chromosomal staining and are available for only 16% of Hypsiboas species, a genus accounting for about 10% of the hylid diversity. In this study, cytogenetic data of distinct species and populations of Hypsiboas were analyzed, and the evolutionary dynamics of chromosomal macro- and microstructure of these amphibians were discussed. Contrary to the conservativeness of 2n = 24, this genus is characterized by a high variation of chromosomal morphology with as much as 8 karyotype patterns. Differences in the number and location of nucleolus organizer regions and C-bands allowed the identification of geographical variants within nominal species and cytotaxonomical chromosomal markers. Comparative analyses revealed a strong phylogeographic relationship between chromosomal patterns in this group.

Renal medullary carcinoma response to chemotherapy: a referral center experience in Brazil

Renal medullary carcinoma (RMC) is rare, accounting for less than 1% of all renal neoplasms. Case reports suggest RMC is highly aggressive, poorly responsive to chemotherapy, often metastatic at diagnosis, affects young men with sickle cell trait, and median overall survival (mOS) is less than 12 months. We report the epidemiological characteristics, treatments performed, response rate to each treatment and mOS of five patients with RMC. All patients had sickle cell trait, four were male, three had metastatic disease at diagnosis and mean age at diagnosis was 25 years. Non-metastatic patients were submitted to nephrectomy. Two patients had partial response to first line chemotherapy including cisplatin and gemcitabine. There was no response to sunitinib or second line chemo - therapy; mOS was 6 months. Due to its rarity, case series are the only evidence available to discuss the treatment for RMC. In our experience, only cisplatin and gemcitabine based regimen offered response.

Implementing human papillomavirus testing in a public health hospital: challenges and opportunities

OBJECTIVES

Robust evidence now supports human papillomavirus (HPV) testing as a more effective option to screening and as more sensitive than cytology in detecting high-grade cervical intraepithelial neoplasia . Our goal was to analyze the performance of the Hybrid Capture II (HC2) assay for high-risk HPV (hrHPV) in women undergoing gynecological examination at a public health hospital as part of the evaluation of HPV screening as an alternative or complement to cytology.

STUDY DESIGN

This analysis is a subset of a cross-sectional study carried out at a large public hospital serving a predominantly low-resource population. A total of 705 women were enrolled; the sensitivity and specificity of each test were estimated and compared.

RESULTS

The analysis identified 272 hrHPV-positive women (mean age 36.3 years) and 433 hrHPV-negative women (mean age 41.2 years). HPV testing showed a significantly increased sensitivity of the HC2 assay versus cytology (84.5 vs. 69.7%; p < 0.0001) but a lower specificity (49.90 vs. 88.78%; p < 0.0001).

CONCLUSION

The combination of both methods seems to be useful in improving detection of cervical lesions.

Indeterminate leprosy: histopathologic and histochemical predictive parameters involved in its possible change to paucibacillary or multibacillary leprosy

In an attempt to find clinical, bacteriological, histopathological, and immunohistochemical parameters to predict the progress of indeterminate leprosy patients to either paucibacillary (PB) or multibacillary (MB) leprosy, skin biopsies from 51 patients with indeterminate leprosy were retrieved from the files of the São Paulo Health Institute (Brazil). All of these patients had progressed to either PB or MB leprosy over a period of time which varied from 2 months to 24 years. Clinical records were examined, and new sections were cut from the paraffin blocks and stained by hematoxylin-eosin and Fite-Faraco stains; the avidin-biotin peroxidase technique was used with primary antibodies to detect bacillary antigens (anti-BCG serum) and nerve branches (anti-S-100 protein anti-serum). A moderate (++) or strongly positive ( ) Mitsuda skin test was observed in some patients progressing to PB leprosy. Noteworthy is that even patients initially Mitsuda negative may evolve to PB leprosy. a) A 2+ bacterial index and/or the presence of bacilli, even though few in number, in various dermal structures; b) multiple positive antigen sites as detected by anti-BCG anti-serum; and c) dermal nerve involvement, when evaluated as single parameters, correlated with a progression indeterminate to MB leprosy. An index resulting from the summation of the above three parameters identified 13 (72%) of 18 of these cases which progressed to MB leprosy.