Cerebral Venous Sinus Thrombosis as a First Presentation of Glucagonoma

Abstract Background: Glucagonoma is a very rare type of pancreatic neuroendocrine tumor (pNET) which represent about 2% of all pNETs (Yao et al.). Although glucagonoma can occur in multiple endocrine tumor syndromes (e.g., MEN-1), most cases are non-hereditary (John & Schwartz). The typical 4Ds presentation are diabetes (DM), depression, dermatosis, & deep vein thrombosis (DVT) (Cunha-Silva et al.). About 50% of glucagonoma patients have DVT during their disease course (Feingold et al.). Most reported DVT cases in glucagonoma are either lower limb DVT or pulmonary embolism (Teixeira, Nico & Ghideti; Castro et al.). To our knowledge, there is no report of a cerebral venous sinus thrombosis (CVST) as the first presentation for glucagonoma. Clinical Case: A 67-year-old male with a history of psoriasis & benign prostatic hyperplasia presented to the emergency department with a diffuse headache. He was sent home with conservative management. Four days later, he developed acute left-sided weakness with numbness & facial droop. CT head with contrast revealed a superior sagittal sinus thrombosis extending into the right transverse & right sigmoid sinuses. Heparin infusion was initiated. Due to the extensive sinus vein thrombosis & lack predisposing conditions, a pan CT was done for possible malignancy. The scan showed a solid, well-defined, markedly enhancing lesion in the pancreatic tail, suggestive of a NET. At the same time, a new diagnosis of type 2 DM was made based on HbA1C of 11.8%. The patient denied any diarrhea, fever, abdominal pain or episodes suggestive of hypoglycemia. However, he endorsed night sweats with weight loss. His family history was significant for a brother who had a pNET that was resected. Endocrinology was consulted, & a workup for pNET was ordered. Chromogranin A (CgA) was elevated at 439.9 ng/ml (<=82), while on PPI. 24-hour urine cortisol was normal. PTH, serum calcium, & the pituitary hormonal panel were all normal. hCG & CEA were normal. Given the new onset DM & DVT plasma glucagon was requested & came back elevated at 202 pg/ml (reference range 80 pg/ml). MRI showed an hypervascular T2 isointense lesion at the pancreas’ tail measuring 10 x 11 x 10 mm. A Ga68-DOTATATE PET scan was ordered. With this constellation of findings, we initiated somatostatin analog therapy while surgical resection was planned. We referred the patient to medical genetics. Conclusion: DVT is a common presentation in glucagonoma & a major cause of mortality. The possible mechanism appears to be related to increased secretion of factor X by pancreatic alpha cells (Lobo et al.). Although DVT is not unusual, an extensive CVST as the first presentation in glucagonoma has not been reported. In this case, & in addition to unexplained DVT, the new diagnosis of DM in an elderly patient raised the suspicion of secondary causes. Such a presentation should encourage clinicians to broaden the differential diagnoses, including pNET.

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