INSULINLIKE ACTIVITY OF NONPANCREATIC TUMORS ASSOCIATED WITH HYPOGLYCEMIA

Case report: hypoglycemia secondary to a meningioma

Hypoglycemia secondary to a meningioma that has not metastasized to the liver has not been reported previously. A 41-year-old woman with a spinal cord meningioma first diagnosed 5 years previously with 3 recurrences in the spinal cord resulting in 4 neurosurgical procedures was admitted with a serum glucose of 23 mg/dL. Six months before the current admission, the patient was noted to have an abdominal mass of 10 cm not present on previous computed tomography. Three months later, the mass was 15.2 cm, and on the current admission, had increased to 23 cm and encased both the aorta and inferior vena cava. A needle biopsy of this mass before referral to the authors' hospital with hypoglycemia revealed that it was a meningioma. Evaluation of the etiology of the hypoglycemia, which required continuous intravenous glucose therapy, revealed that circulating insulin, C-peptide (i.e., connecting peptide), insulin-like growth factor-I (i.e., somatomedin-C) and insulin-like growth factor-II were all normal or low. Serum cortisol also was not low. Based on her endocrine evaluation, the hypoglycemia was secondary to the large mass of tumor cells, requiring a large glucose uptake to sustain its growth. After radiation therapy of 3,770 CGy to the meningioma, the patient became euglycemic without glucose supplementation.

Mesenchymal tumors associated with hypoglycemia: case report and review of the literature

Hypoglycemia secondary to malignant tumors is rare. Mesenchymal tumors of nonpancreatic origin are the most common tumors associated with the hypoglycemia syndrome, and the clinical features of 115 reported cases are reviewed. The major anatomic distributions of the tumors are thoracic (30%) abdominal (65%), and uncommon locations (less than 5%). Approximately 50% of the tumors were resectable (59 patients), and in 60% the surgical procedure was curative. In the remaining 40% local recurrence predominated related to site of tumor and presence of contiguous organ invasion. The application of multimodality adjuvant therapy for hypoglycemia associated mesenchymal tumors should be based on an understanding of the natural history of the tumor.

Ectopic insulin and Occam's razor: reappraisal of the riddle of tumour hypoglycaemia

The concept of ectopic insulin production is challenged on the basis of a review of 120 cases from the literature on extrapancreatic tumours associated with hypoglycaemia in which insulin or insulin-like activity were measured. No case met two or more of five criteria of ectopic hormone production. The evidence indicates that hypoglycaemia of extrapancreatic tumours cannot be attributed to insulin. In those rare cases in which plasma insulin was reported as high, pancreatic beta-cells could not be excluded as the source of insulin. Interestingly, many of these dubious cases had carcinoid histology. The review also points out a close association between some spindle-cell tumours and carcinoid tumours which may be relevant to discussion on the disputed origin of some "mesothelial" tumours. Nonsuppressible insulin-like activity (NSILA) consists of a number of factors mimicking insulin activity which compete with insulin or proinsulin for membrane receptors and may crossreact in bioassays, immunoassays, and receptor assays. The question of whether one or several of these substances may be responsible for extrapancreatic hypoglycaemia remains to be elucidated.

Aberrant hormone activity by tumors of gynecologic importance

Increasing numbers of endocrine active tumors are being reported. The production of hormonal substances not generally associated with the tissues involved may directly or indirectly concern the gynecologist. Identification of these occurrences may be important in the diagnosis of occult neoplasms or obscure tumor effects. In addition, observation of the level of aberrant hormone secretion may be important therapeutic and prognostic measure. Detection may result from the investigation of apparent inappropriate and endocrine syndromes or routine screening in cases of known tumors. Proof of the actual production of hormone by the tumors and complete identification of the material in question generally requires extensive biologic, chemical, physical, and immunologic investigation. The most likely mechanisms for aberrant hormone production by tumors are derepression of the genome or the occurrence of chance biosynthetic anomalies coincident with neoplastic nuclear alterations. Endocrine active substances of interest to the gynecologist produced under these circumstances include gonadotropin, lactogens, thyrotropins, and adrenocortico-tropin, as well as calcium-mobilizing and erythropoietic substances.