Mutations seen among patients with pheochromocytoma and paraganglioma at a referral center from India

Characteristics and genetic testing outcomes of patients with clinically suspected paraganglioma/pheochromocytoma (PGL/PCC) syndrome in Singapore

BACKGROUND

Hereditary paraganglioma (PGL) and pheochromocytoma (PCC) syndromes are rare conditions, with limited data on spectrum of causative gene variants of these syndromes in Asian patients.

METHODS

We describe the clinical characteristics and genetic testing outcomes of patients with suspected hereditary PGL/PCC who were referred to a tertiary cancer genetics clinic in Singapore.

RESULTS

Among 2196 patients with suspected hereditary cancer syndrome evaluated at the cancer genetics clinic from 2000 to 2019, 13/2196 (0.6%) patients fulfilled clinical suspicion for hereditary PGL/PCC syndrome. After genetic counselling, 10 patients underwent multi-gene next generation sequencing and deletion/duplication analysis, including SDHAF2, SDHA, SDHB, SDHC, SDHD, VHL, NF1, RET, MAX, and TMEM127. Seven of 10 patients (70%) were identified to carry pathogenic variants, including 3 unrelated Chinese patients with head and neck PGL who carried the same SDHD: c.3G > C (p.Met1Ile) variant that was previously reported to be a possible founder variant in Chinese, and 3 patients with urogenital PGL and 1 patient with retroperitoneal PGL who carried different SDHB variants. Variant carriers were younger, more likely to present with multiple tumours, or have family history of paraganglioma or pheochromocytoma, than non- variant carriers.

CONCLUSION

Hereditary PGL/PCC accounts for only 0.6% of patients seen in an adult cancer genetics clinic in Asia. SDHD and SDHB genes remain the most important causative genes of hereditary PGL/PCC in Asia even when patients are tested with multi-gene NGS panel.

Case of functioning thoracic paraganglioma

Functioning thoracic paraganglioma (PGL) is rare in clinical practice. We present a 33-year-old man with this pathology, who came with right-sided chest pain and was found to have a right-sided paravertebral mass. Fine needle aspiration cytology revealed a PGL. Urine normetanephrine was elevated and meta- iodobenzylguanidine scan showed increased tracer uptake in the right hemithorax, suggestive of a functioning neuroendocrine tumour. The patient was subjected to right PGL excision by video-assisted thoracoscopic surgery, after adequate preoperative preparations. The perioperative period was uneventful, except for a transient rise in blood pressure during the surgery. His blood pressure continued to be normal in the postoperative period. In any patient with a paravertebral mass, the possibility of PGL should be kept in mind even if the patient is normotensive. Making a preoperative diagnosis is important, because excision of functioning PGL without adequate preoperative preparation may be detrimental.

Genetic Profile of Indian Pheochromocytoma and Paraganglioma Patients - A Single Institutional Study

BACKGROUND AND AIMS

Pheochromocytomas (PCCs) and Paragangliomas (PGL) are rare catecholamine producing tumors that may present in sporadic or familial settings. Despite vast strides in understanding of PCC/PGL genetics in the last two decades, there is a dearth of information from India. The aim here is to study the prevalence of genetic mutations in Indian PCC/PGL patients.

SETTINGS AND DESIGN

Tertiary care academic hospital; prospective study.

METHODS

50 histopathologically diagnosed PCC/PGL patients formed the study group. Clinical, biochemical, pathological attributes and outcomes were documented and the phenotype was compared to the genotype. Succinyl dehydrogenase (SDH), Re-Arranged during Transfection (RET), Von-Hippel-Lindau (VHL) and NeuroFibromatosis-1 (NF1) mutations were studied. Additionally, immunohistochemisty for SDHB was also done, and the results compared to mutational analysis of SDH by MLPA (Multiplex Ligation-dependent Probe Activation).

STATISTICAL ANALYSIS

Independent samples t-test and Fisher's exact test were used as appropriate. P values ≤0.05 were considered statistically significant.

RESULTS

The mean age was 34.3 years. Of the 50 patients, 27 were males and 23 females. 10 patients (20%) in all were detected to have a genetic mutation. 6 patients possessed a RET mutation, while two had VHL mutations. No patient presented with a NF1 mutation. 2 patients had a SDH mutation, and Immunohistochemistry for SDHB correlated with mutational analysis for these patients.

CONCLUSIONS

The proportion of patients with a familial variant of PCC/PGL is more than what the historic "Rule of Ten" suggests. Our study found that one in five patients have a genetic mutation. PCC/PGL patients with genetic mutations not only require more stringent follow-up, but also screening of family members.

Re-operative Surgery for Pheochromocytoma-Paraganglioma: Analysis of 13 Cases from a Single Institution

Re-operative adrenal surgery for recurrent pheochromocytoma/paraganglioma (PCC/PGL) is a therapeutic situation not commonly encountered. The recurrence rate of pheochromocytoma is estimated to be 6.1-16.5% of patients from published retrospective series; there are no reports from the Asian continent. A retrospective analysis of the departmental database was performed on patients who had undergone surgery for PCC/PGL from January 2004 to December 2014 at the Christian Medical College Hospital, Vellore, India. Among 99 patients identified during the study period, there were 14 recurrent tumours and 13 patients underwent re-operative surgery. We located eight recurrences on the right side, three on the left side and three in the midline. All 14 recurrences were functioning, and the biochemical analysis as well as imaging studies were positive in 13 of them. The mean duration to recurrence from the time of the primary surgery was 76.3 months (range 6-180 months). Of the 89 patients who underwent their first operation at our centre, 67.4% reported for follow-up for a mean period of 25 months (range 4-132 months). Four of these required re-operation with a recurrence rate of 4.5% (4/89). The open approach was used for all but one of the recurrent tumours. Recurrence following surgery for PCC/PGL is a rarely studied though significant problem. Right adrenal tumour recurrences were most common, and all these recurrences were in the retrocaval region; this typical phenomenon may be dubbed the 'right retrocaval trap'. The reason for this was presumably due to difficult access and inadequate exposure of this area in open and laparoscopic surgery, resulting in incomplete dissection.

Genotype-Phenotype Correlation in Indian Patients with MEN2-Associated Pheochromocytoma and Comparison of Clinico-Pathological Attributes with Apparently Sporadic Adrenal Pheochromocytoma

INTRODUCTION

Pheochromocytoma (PCC) manifests in up to 50% of MEN2 patients. We correlated the clinico-pathological features of MEN2-associated PCC (MEN-PCC) with RET mutations and compared them with non-MEN adrenal-PCCs.

METHODS

In this retrospective single institution study on a large PCC database (n = 208, 1997-2014) 24 MEN-PCC patients with known RET mutations were reviewed. Excluding 7 with incomplete data, the study cohort of 17 MEN-PCC patients from 11 kindreds (M:F::7:10) was identified. Clinical, biochemical, pathological attributes, and outcomes in the MEN-PCC group were correlated with the genotype, and further compared with non-MEN, apparently sporadic adrenal-PCCs (n = 132, excluding 37 extra-adrenal and 15 VHL/NF1/SDH-associated PCC).

RESULTS

Components of MEN2 encountered included MTC in 13(76.5%), Marfanoid habitus in 2, and PHPT, cutaneous lichen amyloidosis and mucosal neuromas in 1 patient each. In 11(64.7%), PCC was the first detected MEN2 component (Symptomatic:8, Incidentaloma:3). Four (23.5%) were normotensive; 8(47.1%) had bilateral PCC (7 synchronous, 1 metachronous). Surgery for PCC included laparoscopic adrenalectomy in 12; and cortical-sparing adrenalectomy in 2 of 8 bilateral PCC patients. Mean MEN-PCC tumor size was 6.9 ± 3.9 cm, and 6(35%) had additional adrenal medullary hyperplasia. Four different genotypes were encountered, commonest involving codon 634, others being 804 and 918. Mean age in MEN-PCC (27.7 ± 12.2 years) was lower than non-MEN PCC (39.4 ± 15.7, p = 0.018). Proportion of pediatric patients (35.3% in MEN-PCC vs. 12.9% in non-MEN-PCC, p = 0.007), bilateral tumors (47.1% in MEN-PCC, 4.5% in non-MEN-PCC, p < 0.001), and adrenal medullary hyperplasia (35.2% in MEN-PCC, 0.7% in non-MEN-PCC, p < 0.001) were different. Median 24-hour urinary metanephrines was significantly higher in index MEN-PCC patients, than non-MEN-PCC (634 vs. 214 mcg/24 h, p value = 0.006), but was non-significantly higher in non-index MEN-PCC patients. Mean tumor sizes were comparable in the two groups. None of MEN-PCC patients had malignant PCC, compared to 7(5.3%) in non-MEN-PCC.

CONCLUSIONS

In this cohort of MEN-PCC from India, the commonest causative RET mutations for MEN-PCC involved codon 634. MEN-PCC patients were younger, and more frequently had bilateral PCC than non-MEN disease. MEN-PCC patients in India are diagnosed with large tumors and extremely high catecholamine/metanephrine levels.