Endocrine Abstracts

Introduction

Paragangliomas (PGLs) are neuroendocrine tumours that arise from neural crest-derived chromaffin cells. They can develop anywhere these cells exist from the base of the skull to the pelvis. All PGLs have neuro-secretory potential and can produce symptoms due to catecholamine excess. While the majority are benign they do have malignant potential. Mediastinal PGLs are rare and often have a strong genetic predisposition. A higher proportion of these tumours can be secretory when comparted to head and neck PGLs. Novel functional imaging modalities have increased tumour detection rates. Surgical resection is often challenging due to their proximity to vital structures. Here we present our experience of 8 patients with mediastinal PGLs with a median of 5.5 years follow up (range 2–16 years).

Case descriptions

We report 8 cases (3 female, 5 male) of mediastinal PGLs in patients aged 19–81 years (median age 58). 5 presented with a solitary mediastinal PGL, 2 with multiple lesions and 1 with metastatic spread. 4/8 were diagnosed as a result of cascade screening. These all had a heterozygous pathogenic SDHB variant and were asymptomatic. Genetic analysis of the remaining 4 patients revealed no genetic abnormality in 3/8 and an SDHA variant of uncertain significance in 1/8. 3/8 were diagnosed incidentally and the remaining 1 patient was diagnosed due to symptomatic catecholamine excess. Serum or urinary samples demonstrated catecholamine excess in 37.5% of cases. The functional imaging modalities utilised included FDG PET (2/8), DOTATATE PET (3/8) and MIBG scintigraphy (7/8). Gallium DOTATE and FDG PET CT demonstrated 100% sensitivity in identifying these tumours. MIBG scanning demonstrated 57% sensitivity. 6/8 underwent surgery. 2 patients were diagnosed with ischaemic heart disease pre-operatively and underwent a simultaneous coronary artery bypass graft. Post-operative follow up ranges from 1 to 16 years. No recurrent or metastatic disease has been identified in these 6 cases. 1/8 was managed conservatively. Peptide receptor radionuclide therapy was used to treat 1 patient with metastatic disease. Latest imaging demonstrates stable disease in these 2 cases

Conclusion

Mediastinal PGLs are rare but carry a strong genetic predisposition. More are being identified due to improved functional imaging techniques. Interpretation of these imaging modalities requires careful consideration. A high proportion of mediastinal PGLs can be secretory. Surgical intervention should be performed in a specialist cardiothoracic centre and a multidisciplinary approach is needed for risk stratification, pre- and post-operative management. With this approach excellent outcomes can be achieved.