Plasma glucagon levels suppressed by a glucose load in a man with incidental pancreatic glucagonoma.

OBJECTIVE: To describe a patient with a histologically proven pancreatic glucagonoma, noted incidentally during a follow-up visit for high aminotransferase levels, and to evaluate its autonomy with a standard 75-g oral glucose tolerance test. METHODS: We present the results of a 2-hour oral glucose tolerance test, with plasma glucagon and blood glucose levels measured every 30 minutes after an oral glucose load. In addition, we provide a brief review of the literature on the diagnosis and management of glucagonomas and the importance of long-term surveillance. RESULTS: In our patient, who had a 1-year history of impaired fasting glucose, plasma glucagon levels were persistently suppressed to within the normal range after oral glucose challenge. Octreotide scintigraphy revealed abnormal uptake in the pancreatic tail, and a 2.8-cm mass was removed at laparoscopic distal pancreatectomy. Immunohistochemical staining of the tumor tissue showed intense reactivity for glucagon. Plasma glucagon levels were reduced to <50 pg/mL postoperatively, and scintigraphic study at 4-month follow-up showed no residual uptake at the previous tumor site or elsewhere. CONCLUSION: Glucagon-secreting pancreatic tumors are extremely rare. A substantially elevated plasma level of glucagon is usually seen in patients with metastatic tumors. In the early stage of a glucagonoma, however, the plasma glucagon level may be only modestly elevated and may still be susceptible to normal negative feedback inhibition. We demonstrated plasma glucagon complete suppressibility after oral glucose challenge in a patient with a glucagonoma, the first such report in the literature.

Littoral cell angioma presenting as metastatic thyroid carcinoma to the spleen.

Papillary thyroid carcinoma (PTC) commonly metastasizes to cervical lymph nodes. Distant metastases are unusual with the lungs most frequently involved. Well-differentiated thyroid carcinoma very rarely presents with metastases to the spleen. This is the case of a 25-year-old man with a history of PTC (1.4 cm primary; no capsular invasion and negative lymph node metastases). One year after initial surgery, recurrent disease was found in multiple neck nodes by central neck dissection. Whole body scan (WBS) following a therapeutic ablation dose of 150 mCi I(131) revealed mediastinal metastases. Computerized axial tomography (CT) of the chest one year later showed no gross mediastinal or pulmonary disease. However, multiple large splenic lesions were incidentally noted. Evaluation by ultrasound (US) showed lesions to be solid echogenic masses without remarkable Doppler characteristics to suggest vascular tumors. US-guided percutaneous fine-needle aspiration biopsy (FNAB) of one lesion was nondiagnostic. After withdrawal from Levothyroxine, serum TSH was >100 mU/L with a thyroglobulin of 9.4 ng/mL and negative anti-thyroglobulin antibodies. Diagnostic WBS revealed faint splenic uptake but was otherwise unremarkable. Following treatment with 192 mCi I(131), WBS demonstrated increased activity in the mediastinum as well as in the spleen suggesting mediastinal and splenic metastases. Contrast CT of the abdomen showed multiple low-attenuated heterogeneously enhancing splenic masses, normal liver and no intra-abdominal lymphadenopathy. The largest mass (4.5 x 3.5 cm) was exophytic and in close proximity to the splenic capsule. Despite the serum thyroglobulin of only 9.4 ng/mL, the finding of I(131) accumulation within solid splenic masses led to a preoperative diagnosis of thyroid carcinoma metastases. To establish the diagnosis and to remove the risk for splenic rupture, a laparoscopic splenectomy was performed. Histopathologic analysis showed large littoral cell angiomas (LCA). False-positive radioiodine scintigraphy in the setting of PTC involving a vertebral hemangioma has been reported. To our knowledge, this is the first case that describes multiple angiomas mimicking metastatic thyroid carcinoma to the spleen. In one-third of all cases reported, LCA co-exists with various visceral organ cancers or malignant lymphoma. This is the first report of an association between LCA and thyroid carcinoma.