Durable and deep response to CVD chemotherapy in SDHB-mutated metastatic paraganglioma: case report

Abstract

Introduction: Succinate dehydrogenase subunit B (SDHB)-mutated paragangliomas (PGLs) are rare neuroendocrine tumors characterized by increased malignancy, readily metastasizing, and poorer prognosis. Here we report a case of SDHB-mutated metastatic PGL, wherein the patient showed significant tumor shrinkage and complete symptom remission following chemotherapy. We aim to contribute additional evidence to the existing knowledge associated with SDHB-mutated PGLs.

Case report: A 40-year-old male patient presented with recurrent hypoglycemia and hypertension crisis. Imaging revealed a huge left retroperitoneal tumor and multiple diffuse metastases in lungs. Catecholamine was also elevated, aligning with a diagnosis of metastatic PGL. Pathology also confirmed this diagnosis. Additionally, the immunohistochemistry indicated negative expression of SDHB and gene test showed somatic SDHB mutation. Given the SDHB mutation, cyclophosphamide-vincristine-dacarbazine (CVD) chemotherapy was initiated in critical conditions. Subsequently, a significant tumor shrinkage and complete biochemical response were observed after two treatment cycles. In September 2024, CT scan revealed new pulmonary lesions. The progression-free survival (PFS) with CVD chemotherapy was 24 months.

Conclusion: This report reviews the distinct clinical and biochemical characteristics and treatment approaches of SDHB-mutated paragangliomas, emphasizing that the significance of incorporating both genetic testing and immunohistochemical analysis in clinical practice.

Keywords: CVD chemotherapy; SDHB-mutation; case report; hypoglycemia; metastatic paraganglioma.

Figure 1

(A, D, G, J) Prior to CVD chemotherapy, CT revealed retroperitoneal lesions around the pancreas, liver, kidney and multiple diffuse lesions in both lungs. (B, E, H, K) After 2 cycles of CVD chemotherapy, CT revealed that retroperitoneal lesions around the pancreas, liver, kidney and multiple diffuse lesions in both lungs reduced in size. (C, F, I, L) After 20 cycles of CVD chemotherapy, CT revealed retroperitoneal lesions further reduced in size. Although a small amount of lung lesions enlarged and new lesions appeared, the majority of lung lesions reduced in number and size. [Red arrows indicate shrinking lesions, yellow arrows indicate enlarged lesions, and green arrows indicate new lesions.].

Figure 2

Pathological findings of the retroperitoneal lesion. (A) Haematoxylin and eosin staining. (B) Ki67 positive rate was 60%. (C) The expression of SDHB was negative.

Figure 3

(A–F) Prior to CVD chemotherapy, 18F-FDG positron emission tomography (PET-CT) revealed increased uptake of 18F-FDG in the left retroperitoneal mass, lung masses and humeral head. The maximum cross-sectional area of the left retroperitoneal mass was approximately 166 × 99mm, with maximum SUV sizes of 21.49. (G–L) Prior to CVD chemotherapy, 68Ga-DOTATATE PET-CT revealed increase uptake of 68Ga-DOTATATE in the left retroperitoneal mass, lung masses and humeral head. The maximum SUV sizes of the left retroperitoneal mass was 36. 94.