Abstract
OBJECTIVE: Data on succinate dehydrogenase-related pheochromocytoma and paraganglioma (SDHx PPGL) in India are limited. We describe the clinical and genetic characteristics of SDHx PPGL from a single center in western India. DESIGN, PATIENTS, AND MEASUREMENTS: A retrospective review of SDHx PPGL patients was performed for clinical, imaging, genetic, and treatment details. RESULTS: Among 46 patients (39 probands, 24 males), the median age at diagnosis was 32.5 (IQR: 23-41) years. We report the youngest patient with SDHC (age 8 years). SDHB mutations were the most prevalent (24/39 probands), followed by SDHD, SDHC, SDHA, and SDHAF2. We report the first Indian family with the SDHAF2 c.232G>A mutation (paternal inheritance) and the index patient with metastasis. Paraganglioma (PGL) (single or multiple) was common (80%), followed by pheochromocytoma (11%) and multifocal PPGL (9%). sPGL predominated in the SDHB cohort (80.6%), whereas multiple/multifocal PPGLs were common in others. Biochemically silent tumors were noted in 26% patients. 68Ga-DOTATATE PET/CT was the most sensitive imaging modality. The prevalence of metastasis was high in patients with SDHB variants (51.7%) but was also substantial in those with other SDHx genes (29.4%). Most probands harbored unique variants, and we report ten novel SDHx gene mutations. Surgical treatment was performed in 67.3% cases, and systemic radiotherapy was utilized in advanced cases, achieving stable disease in most cases. CONCLUSION: In this largest Indian cohort of SDHx PPGL, a high metastatic burden, SDHB dominance, and novel gene variants were noted.