Insulin-secreting bronchial carcinoid tumor with widespread metastases

Approach to the Patient: Insulinoma

Insulinomas are hormone-producing pancreatic neuroendocrine neoplasms with an estimated incidence of 1 to 4 cases per million per year. Extrapancreatic insulinomas are extremely rare. Most insulinomas present with the Whipple triad: (1) symptoms, signs, or both consistent with hypoglycemia; (2) a low plasma glucose measured at the time of the symptoms and signs; and (3) relief of symptoms and signs when the glucose is raised to normal. Nonmetastatic insulinomas are nowadays referred to as "indolent" and metastatic insulinomas as "aggressive." The 5-year survival of patients with an indolent insulinoma has been reported to be 94% to 100%; for patients with an aggressive insulinoma, this amounts to 24% to 67%. Five percent to 10% of insulinomas are associated with the multiple endocrine neoplasia type 1 syndrome. Localization of the insulinoma and exclusion or confirmation of metastatic disease by computed tomography is followed by endoscopic ultrasound or magnetic resonance imaging for indolent, localized insulinomas. Glucagon-like peptide 1 receptor positron emission tomography/computed tomography or positron emission tomography/magnetic resonance imaging is a highly sensitive localization technique for seemingly occult, indolent, localized insulinomas. Supportive measures and somatostatin receptor ligands can be used for to control hypoglycemia. For single solitary insulinomas, curative surgical excision remains the treatment of choice. In aggressive malignant cases, debulking procedures, somatostatin receptor ligands, peptide receptor radionuclide therapy, everolimus, sunitinib, and cytotoxic chemotherapy can be valuable options.

The Surgical Management of Lung Neuroendocrine Neoplasms

This review summarizes key recent developments relevant to the surgical management of lung neuroendocrine neoplasms (L-NENs), including typical and atypical carcinoids, large cell neuroendocrine carcinoma, and small cell lung carcinoma. This review includes recent insights into the classification, clinical presentation, diagnostic workup, treatment options, and follow-up. Highlighted topics include general principles of surgery in localized or locally advanced or metastatic L-NENs, lung-sparing surgery for small, peripheral typical carcinoids, adjuvant and systemic therapies for typical and atypical carcinoids, and surgery and adjuvant therapies for large cell neuroendocrine carcinoma and small cell lung carcinoma.

Solid pancreatic masses in children: A review of current evidence and clinical challenges

Pancreatic tumors in children are infrequently encountered in clinical practice. Their non-specific clinical presentation and overlapping imaging characteristics often make an accurate preoperative diagnosis difficult. Tumors are categorized as epithelial or non-epithelial, with epithelial tumors further classified as tumors of the exocrine or endocrine pancreas. Although both are tumors of the exocrine pancreas, solid pseudopapillary neoplasm is the most prevalent solid pancreatic tumor in children, while pancreatoblastoma is the most common malignant tumor. Insulinoma is the most common pediatric pancreatic tumor of the endocrine pancreas. Malignant tumors require a complete, often radical, surgical resection. However, pancreatic parenchyma-sparing surgical procedures are utilized for benign tumors and low-grade malignancy to preserve gland function. This review will discuss the epidemiology, pathophysiology, clinical and diagnostic characteristics, and management options associated with both common and rare solid pancreatic masses in children. We will also discuss current challenges encountered in their evaluation and treatment.

Phaeochromocytomas overexpress insulin transcript and produce insulin

INTRODUCTION

Phaeochromocytomas are tumours originating in the medulla of the adrenal gland. They produce catecholamines, and some tumours also produce ectopic hormones. Two types of glucose imbalances occur in phaeochromocytoma patients, hyperglycaemia and hypoglycaemic attacks. Therefore, we tested whether insulin transcript (INS), insulin, and a hybrid read-through transcript between exons from insulin and insulin-like growth factor 2 (INS-IGF2) were expressed in phaeochromocytomas.

METHODS

We measured the expression of insulin using immunohistochemistry. The expression of INS-IGF2 was determined by qRT-PCR in formalin-fixed and paraffin-embedded tissue from 20 phaeochromocytomas. The expression of INS and INS-IGF2 transcriptswas also analysed in 182 phaeochromocytomas and paragangliomas using publicly available datasets in The Cancer Genome Atlas (TCGA) Database.

RESULTS

Of 20 phaeochromocytomas, 16 stained positive for insulin. The distribution of positive cells was mostly scattered, with some focal expression indicating clonal expansion. Nineteen tumours expressed high levels of INS and INS-IGF2 transcripts. The expression of the two transcripts corresponded closely. In the TCGA dataset, phaeochromocytoma expresses higher levels of INS and INS-IGF2 transcripts compared to the normal non-tumour adrenal glands. Thus, the expression of INS and INS-IGF2 seems to be a general phenomenon in phaeochromocytoma.

CONCLUSION

Most phaeochromocytomas contain cells that overexpress INS and INS-IGF2 transcripts. Most tumours also display heterogeneous expression of polypeptides immunoreactive to monoclonal anti-insulin antibodies. Clinically this may relate to both hyperglycaemia and hypoglycaemic attacks seen in patients with phaeochromocytoma as well as autocrine tumour growth.

Primary Functioning Neuroendocrine Tumor of the Appendix with Hypoglycemia Syndrome: A Case Report and Review of Neuroendocrine Tumors

INTRODUCTION

Primary neuroendocrine tumors (NETs) of the appendix are uncommon, but when present are usually not hyperfunctioning. This case represents an extraordinarily rare primary hyperfunctioning NET of the appendix with a clinical presentation of symptomatic hypoglycemia in an otherwise healthy man.

CASE PRESENTATION

A previously healthy 34-year-old man was found to be symptomatically hypoglycemic in early 2018. After the workup, the apparent explanation was a tumor in his midappendix, for which he was referred to our surgical oncology service for resection. The patient's clinical course is described in detail, including imaging, as well as surgical and pathologic descriptions of the appendiceal NET.

DISCUSSION

A literature review demonstrates no other case series or reports of a primary hyperfunctioning NET of the appendix presenting with hypoglycemic crisis. The symptoms of tumor-induced hypoglycemia more typically arise with islet cell tumors, such as pancreatic NETs or insulinomas. We believe this case represents a nonislet cell tumor-induced hypoglycemia. This patient's elevated serum proinsulin level preoperatively implies secretion of proinsulin by the tumor. However, tumor-induced hypoglycemia caused by proinsulin has been described previously only in pancreatic tumors. This unique case adds knowledge to the possible glycemic endocrine effects of nonpancreatic NETs, specifically those that arise primarily in the appendix.

Paraneoplastic syndromes and other systemic disorders associated with neuroendocrine neoplasms

Neuroendocrine paraneoplastic syndromes (PNS) consist of metabolic disorders that accompany benign and malignant neoplasms but remain unrelated to mass effects or invasion by the primary tumor or its metastases. The underlying pathogenesis responsible for PNS usual clinical presentation relies on aberrant production of protein hormones, proteins and other substances by the tumor. Prompt recognition of characteristic signs and symptoms combined with serological identification of key substances may result in early diagnosis of PNS and its underlying malignancy. For these reasons, healthcare professionals should familiarize themselves with tumor-induced hypercalcemia, syndrome of inappropriate antidiuretic hormone, carcinoid syndrome, virilisation syndrome, gynecomastia, acromegaly, Cushing syndrome, osteogenic osteomalacia, tumor-induced hypoglycemia, necrolytic migratory erythema, and watery diarrhea, hypokalemia and achlorydria syndrome. Medical awareness for PNS can improve patient outcomes through earlier administration of cancer therapy and treatment, better symptomatic relief and prolong overall survival.

Hypoglycemia caused by co-secretion of insulin from lung tumor and cardia cancer: first case report

CONTEXT

Non-islet-cell-tumor-induced hypoglycemia (NICTH) is caused on rare occasions by secretion of insulin from tumor cells that are reported to have a single tissue origin.

CASE REPORT

A 67-year-old male patient had cardia adenocarcinoma and concomitant lung adenocarcinoma with extensive metastases and repeated episodes of intractable hypoglycemia. Immunohistochemical staining for insulin showed that lung adenocarcinoma stained positive and gastric cardia adenocarcinoma stained weakly positive. These results indicate that tumor cells of different tissue origins co-secreted insulin.

CONCLUSIONS

This is the first report on intractable hypoglycemia due to co-secretion of insulin from two kinds of primary tumor cells in a single patient.

Glutathione and Transsulfuration in Alcohol-Associated Tissue Injury and Carcinogenesis

Glutathione (GSH) is the most abundant non-protein thiol, attaining cellular concentrations in the millimolar range. GSH functions to protect cells against endogenous and exogenous electrophiles. In addition, GSH serves as a cofactor for the GSH peroxidase family of enzymes which metabolize H₂O₂ as well as lipid peroxides. Through the action of glutathione S-transferase family of enzymes, GSH is conjugated to a variety of electrophilic endogenous compounds and exogenous chemicals, and thereby facilitates their efficient and safe elimination. Through the transsulfuration pathway, GSH biosynthesis is metabolically linked with cellular methylation, which is pivotal for epigenetic gene regulation. Accumulating evidence suggests that the underlying mechanisms of alcohol-associated tissue injury and carcinogenesis involve: (i) generation of the electrophilic metabolite acetaldehyde, (ii) induction of CYP2E1 leading to the formation of reactive oxygen species and pro-carcinogen activation, and (iii) nutritional deficiencies, such as methyl groups, resulting in enhanced susceptibility to cancer development. In this context, clinical and experimental investigations suggest an intimate involvement of GSH and related enzymes in the development of alcohol-induced pathological conditions. The aim of this review is to provide an overview of the GSH biosynthesis, cellular transsulfuration/transmethylation pathways, and their implications in the pathogenesis and treatment of alcohol-related disease and cancer.

Management of pulmonary neuroendocrine tumors

Neuroendocrine tumors (NETs) of the lung are divided into 4 major types: small cell lung cancer (SCLC), large cell neuroendocrine carcinoma (LCNEC), atypical carcinoid (AC) or typical carcinoid (TC). Each classification has distinctly different treatment paradigms, making an accurate initial diagnosis essential. The inconsistent clinical presentation of this disease, however, makes this difficult. The objective of this manuscript is to detail the diagnosis and management of the well differentiated pulmonary carcinoid (PC) tumors. A multidisciplinary approach to work up and treatment should be utilized for each patient. A multimodal radiological work-up is used for diagnosis, with contrast enhanced CT predominantly utilized and functional imaging techniques. A definitive diagnosis is based on tissue findings. Surgical management remains the mainstay of therapy and can be curative. In those with advanced disease, medical treatments consist of somatostatin analog (SSA) therapy, targeted therapy, chemotherapy or peptide receptor radionuclide therapy. SSAs are the standard of care in those with metastatic NETs, using either Octreotide long acting repeatable (LAR) or lanreotide as reasonable options, despite a scarcity of prospective data in PCs. Targeted therapies consist of everolimus which is approved for use in PCs, with various studies showing mixed results with other targeted agents. Additionally, radionuclide therapy may be used and has been shown to increase survival and to reduce symptoms in some studies. Prospective trials are needed to determine other strategies that may be beneficial in PCs as well as sequencing of therapy. Successful diagnosis and optimal treatment relies on a multidisciplinary approach in patients with lung NETs. Clinical trials should be used in appropriate patients.

Paraneoplastic syndromes associated with lung cancer

Paraneoplastic syndromes are signs or symptoms that occur as a result of organ or tissue damage at locations remote from the site of the primary tumor or metastases. Paraneoplastic syndromes associated with lung cancer can impair various organ functions and include neurologic, endocrine, dermatologic, rheumatologic, hematologic, and ophthalmological syndromes, as well as glomerulopathy and coagulopathy (Trousseau’s syndrome). The histological type of lung cancer is generally dependent on the associated syndrome, the two most common of which are humoral hypercalcemia of malignancy in squamous cell carcinoma and the syndrome of inappropriate antidiuretic hormone secretion in small cell lung cancer. The symptoms often precede the diagnosis of the associated lung cancer, especially when the symptoms are neurologic or dermatologic. The proposed mechanisms of paraneoplastic processes include the aberrant release of humoral mediators, such as hormones and hormone-like peptides, cytokines, and antibodies. Treating the underlying cancer is generally the most effective therapy for paraneoplastic syndromes, and treatment soon after symptom onset appears to offer the best potential for symptom improvement. In this article, we review the diagnosis, potential mechanisms, and treatments of a wide variety of paraneoplastic syndromes associated with lung cancer.

Ectopic insulin secreting neuroendocrine tumor of kidney with recurrent hypoglycemia: a diagnostic dilemma

BACKGROUND

Hypoglycemia secondary to ectopic insulin secretion of non-pancreatic tumors is rare.

CASE PRESENTATION

We describe a middle aged woman with recurrent hypoglycemia. On evaluation, she was detected to have hyperinsulinemic hypoglycemia and right sided renal mass lesion. 68Ga-Dotanoc and 99mTc-HYNICTOC scans confirmed the intrarenal mass to be of neuroendocrine origin. Right nephrectomy was done and it turned out to be an insulin secreting neuroendocrine tumour. Neuroendocrine nature of this tumour was further confirmed by ultra-structural examination. Her hypoglycemia did not recur after resection of this tumour.

CONCLUSION

Few cases of ectopic insulin secretion have been reported though some are not proven convincingly. This case addresses all the issues raised in previous case reports and proves by clinical, laboratory, functional imaging and immunohistochemical analysis that ectopic origin of insulin by non-pancreatic tumors does occur. To our knowledge, this is the first reported case of ectopic insulinoma arising from the kidney.

Management of endocrine disease: a clinical update on tumor-induced hypoglycemia

Tumor-induced hypoglycemia (TIH) is a rare clinical entity that may occur in patients with diverse kinds of tumor lineages and that may be caused by different mechanisms. These pathogenic mechanisms include the eutopic insulin secretion by a pancreatic islet β-cell tumor, and also the ectopic tumor insulin secretion by non-islet-cell tumor, such as bronchial carcinoids and gastrointestinal stromal tumors. Insulinoma is, by far, the most common tumor associated with clinical and biochemical hypoglycemia. Insulinomas are usually single, small, sporadic, and intrapancreatic benign tumors. Only 5-10% of insulinomas are malignant. Insulinoma may be associated with the multiple endocrine neoplasia type 1 in 4-6% of patients. Medical therapy with diazoxide or somatostatin analogs has been used to control hypoglycemic symptoms in patients with insulinoma, but only surgical excision by enucleation or partial pancreatectomy is curative. Other mechanisms that may, more uncommonly, account for tumor-associated hypoglycemia without excess insulin secretion are the tumor secretion of peptides capable of causing glucose consumption by different mechanisms. These are the cases of tumors producing IGF2 precursors, IGF1, somatostatin, and glucagon-like peptide 1. Tumor autoimmune hypoglycemia occurs due to the production of insulin by tumor cells or insulin receptor autoantibodies. Lastly, massive tumor burden with glucose consumption, massive tumor liver infiltration, and pituitary or adrenal glands destruction by tumor are other mechanisms for TIH in cases of large and aggressive neoplasias.

Bronchopulmonary neuroendocrine tumors

Bronchopulmonary neuroendocrine tumors (BP-NETs) comprise approximately 20% of all lung cancers and represent a spectrum of tumors arising from neuroendocrine cells of the BP-epithelium. Although they share structural, morphological, immunohistochemical, and ultrastructural features, they are separated into 4 subgroups: typical carcinoid tumor (TC), atypical carcinoid tumor (AC), large-cell neuroendocrine carcinoma (LCNEC), and small-cell lung carcinoma (SCLC), which exhibit considerably different biological characteristics. The clinical presentation includes cough, hemoptysis, and obstructive pneumonia but varies depending on site, size, and growth pattern. Less than 5% of BP-NETs exhibit hormonally related symptoms such as carcinoid syndrome, Cushing, acromegaly, and SIADH. SCLC is the most common BP-NET, while LCNEC is rare, approximately 10% and < or =1%, respectively, of all lung cancers. Both SCLC and LCNEC progress rapidly, are aggressively metastatic, and exhibit a poor prognosis. The incidence of BP-carcinoids (TC and AC) in the US was 1.57 of 100,000 in 2003 (an unexplained and substantial increase over the last 30 years, approximately 6% per year). No curative treatment except for radical surgery (almost never feasible) exists. The slow-growing TC exhibit a fairly good prognosis ( approximately 88%, 5-year survival), whereas AC demonstrate a 5-year survival of approximately 50%, and the highly malignant LCNEC and SCLC5-year survival of 15% to 57% and <5%, respectively. This review provides a broad overview on BP-NETs and focuses on the evolution of the disease, general features, and current diagnostic and therapeutic options.

Neuroendocrine tumors of the diffuse neuroendocrine system

PURPOSE OF REVIEW

Neuroendocrine tumors (previously referred to as carcinoids) are ill-understood, enigmatic malignancies that, although slow-growing compared with adenocarcinomas, can behave aggressively. In 2004, they comprised 1.25% of all malignancies; their incidence is increasing by approximately 6% per year. The present review provides an overview on neuroendocrine tumors and focuses on general features and current diagnostic and therapeutic options.

RECENT FINDINGS

Neuroendocrine tumors may present a considerable diagnostic and therapeutic challenge as their clinical presentation is nonspecific and usually late, when metastases are already evident. Topographic localization is by computed tomography, magnetic resonance imaging, somatostatin receptor scintigraphy, whole-body positron emission tomography or endoscopy/ultrasound. Bronchoscopy is useful to verify the diagnosis when lesions are located centrally in the bronchi. No curative treatment except for radical surgery (almost never feasible) exists. Palliative and symptomatic treatment is based on surgical debulking, tumor embolization, and biotherapy with somatostatin analogues. Chemotherapy and radiotherapy are usually ineffective, but novel drugs such as tyrosine kinase receptor inhibitors show promising results in phase II clinical studies.

SUMMARY

Tumors of the diffuse neuroendocrine system represent a significant and increasing clinical problem, and there is a need to develop both early diagnostic tests as well as to establish targeted therapeutic strategies.

Hypoglycemia due to paraneoplastic secretion of insulin-like growth factor-I in a patient with metastasizing large-cell carcinoma of the lung

CONTEXT

Nonpancreatic tumors may cause recurrent hypoglycemia known as nonislet cell tumor hypoglycemia. It is due to overproduction and secretion by the tumor of incompletely processed IGF-II, termed big IGF-II. We recently identified a patient with recurrent hypoglycemia and low insulin, but without elevated big IGF-II. Multiple small lung nodules were detected by computed tomography scan. An undifferentiated large-cell carcinoma was diagnosed from an axillary lymph node metastasis.

OBJECTIVE

The objective was to investigate whether the patient's hypoglycemia was due to excessive IGF-I production by the tumor.

METHODS

Serum IGF- I and IGF-II, insulin, and GH were measured by RIA; the distribution of IGFs between IGF binding protein complexes in serum was analyzed after neutral gel filtration. Tissue IGF-I was identified by immunohistochemistry and in situ hybridization, and by RT-PCR after RNA extraction.

RESULTS

Total and free serum IGF-I, but not total, free, and big IGF-II, was increased, and the IGF-I content of the two IGF binding protein complexes was elevated. Immunohistochemistry demonstrated IGF-I peptide in situ hybridization IGF-I mRNA in the lymph node metastasis. Combined GH/glucocorticoid treatment prevented hypoglycemia, but did not lower IGF-I. After chemotherapy with carboplatinum/etoposide, the lung nodules largely regressed, and serum IGF-I and the IGF-I content of the two binding protein complexes became normal. Hypoglycemia did not recur despite discontinuation of GH/glucocorticoid treatment.

CONCLUSION

Our findings are compatible with a new form of tumor hypoglycemia caused by circulating tumor-derived IGF-I.

Hypoglycemia due to ectopic release of insulin from a paraganglioma

Insulin-secreting pancreatic tumors and insulin-like growth hormone-secreting non-islet cell tumors can cause hypoglycemia. However, insulin-releasing paraganglioma or pheochromocytoma has almost never been reported. A 67-year-old female patient was admitted to our hospital because of headache, palpitation, perspiration, faintness, frequent sense of hunger and absent-mindedness. These intermittent symptoms had begun approximately a year before admission. On physical examination, she had high blood pressure of 150/90 mm Hg. Hormonal studies demonstrated increased urinary norepinephrine levels, and hyperinsulinemic hypoglycemia was confirmed while the patient was symptomatic. Abdominal MRI revealed a retroperitoneal mass measuring 4.5 cm in the pancreatic region. She was treated with an alpha-blocking agent to control blood pressure preceding the removal of the mass. Histopathological diagnosis was paraganglioma, and immunohistochemically insulin staining in the neoplastic cells was demonstrated. Her blood pressure normalized and hypoglycemia relieved after the operation. The patient did not have recurrence of hypoglycemia after a year of follow-up. Paraganglioma is a rare tumor of the neural crest, and co-secretion of insulin and catecholamines has been reported only by a single case report in the literature. The present patient is another case with this co-secretion.

Unusual primary lung neoplasms

Bronchial carcinoids and hamartomas are, respectively, the most common malignant and benign unusual primary lung neoplasms. These tumors are often asymptomatic but can cause central airway obstruction. Helical computed tomographic and radionuclide scintigraphic advances in their detection and evolution, together with newer interventional bronchoscopy techniques such as neodymium:yttrium-aluminum-garnet laser phototherapy and cryotherapy, represent important improvements in the diagnosis and management of patients with such tumors.

Insulin, chemotherapy, and the mechanisms of malignancy: the design and the demise of cancer

The endogenous molecular biology of cancer cells involves autocrine and paracrine secretion of insulin and insulin-like growth-factors I and II, which subserve energy production and growth stimulation, respectively, in these cells. These activities confer on cancer its malignant potential, working as they do autonomously, free from higher levels of integrated control. Taking advantage of cancer's mechanisms of malignancy by employing exogenous insulin as a biologic response modifier, it is possible to potentiate the cytotoxic effects of chemotherapeutic agents for improved treatment of cancer. A synergy between certain membrane and metabolic effects of insulin on cancer cell molecular biology increases anticancer drug efficacy, and it does so with reduced doses of the drugs, enhancing their safety. This treatment strategy has been applied abroad over the last five decades with very promising clinical results.

Aberrant insulinoma of the duodenal bulb

A rare insulin-immunoreactive neuroendocrine tumor of the duodenum in a 54 year old male is reported. The incidentally identified tumor was located on the anterior free wall of the duodenal bulb and measured approximately 6 mm in diameter. Uncomplicated endoscopic resection of the tumor was carried out. The lesion exhibited classic histologic features of insulinoma of the beta-islet cell type with stromal amyloid deposition. In addition to positive reactivities of chromogranin A, neuron-specific enolase, synaptophysin, Leu 7 (CD57), cystatin C, CA15-3 and cytokeratin, the non-argyrophilic tumor cells were strongly immunoreactive for insulin and C-peptide. The stromal amyloid was clearly labeled for amylin. A few cells were stained for somatostatin, whereas other hormones were negative. Interestingly, a few isolated insulin-positive cells were identified in the non-neoplastic duodenal mucosa in the proximity of the tumor. Immunoelectron microscopy using paraffin sections disclosed insulin-immunoreactive secretory granules in the cytoplasm. The patient exhibited no signs or symptoms of hypoglycemia. Serum insulin levels were not measured prior to resection. No tumors were demonstrated in the pancreas. Magnetic resonance imaging revealed a 1 cm asymptomatic pituitary mass, in association with moderately elevated serum prolactin levels. The patient is currently being followed up in the outpatient clinic.

Histopathology and prognostic factors in bronchial carcinoid tumours

Images

Exploration of the pulmonary circulation. Festschrift to Professor Donald Heath

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Insulin-cancer relationships: possible dietary implication

Insulin is a major anabolic hormone in mammals and its involvement in malignancies is well documented. An attempt is made to classify experimental and human cancers into four groups, according to the way the tumors are affected by, or interact with, insulin. Such an approach provides a better understanding of the dietary effects on tumorigenesis. Since human cancers are of the insulin-producing/secreting or insulin-dependent types, it is suggested that screening of individuals for blood insulin level and reducing the insulin status by dietary means may lead to a decreased risk of cancer. Anti-insulin drugs may be useful as supplements to therapeutic treatment.

New approaches to the delivery of drugs to the brain

The Human Immunodeficiency Virus (HIV) is the causative agent of AIDS and this has been found to be neurotropic. For this reason the development of an effective strategy for the delivery of antiviral drugs across the blood-brain barrier is of paramount importance in the treatment of HIV infection. There are insulin receptors on the capillary endothelial cells making up the blood-brain barrier (BBB) and it is proposed that these may play a role, along with exogenously administered insulin, in enhancing the transport of drug molecules across the BBB. Evidence is presented showing that insulin may be used as a pharmacologic adjunct in the therapy of HIV infection by allowing for higher concentrations of antiviral drugs to be obtained within the CNS using lower total doses of drug. This would enhance the drug's therapeutic effectiveness while simultaneously obviating potential dose-related side-effects.

Pancreatic endocrine tumors

In this review the current state of our understanding of endocrine tumors of the pancreas is considered. It is based on the experience with a series of 365 tumors. The first part of the article focuses on origin and classification, markers, frequency, criteria of malignancy as well as general structural features of the pancreatic endocrine tumors. In the second half of the article the functioning tumors, i.e. tumors that cause hormonal syndromes, and the nonfunctioning tumors as well as the endocrine tumors associated with multiple endocrine neoplasia type 1 are dealt with in detail. Special emphasis is put on the immunocytochemical profile and the biological features of the respective tumors.

Diagnosis of lung carcinoid with cutaneous hyperpigmentation eight years after bilateral adrenalectomy

A 26-yr-old male was submitted to bilateral adrenalectomy in 1977 for Cushing's syndrome. Some months later he developed intense skin hyperpigmentation together with increased ACTH levels (149 to 4000 ng/l). The sellar region was always normal in X-ray studies. In April 1985, when the patient complained of chest pain, a chest x-ray showed a polycyclic mass in the upper left lobe of the lung. ACTH ranged from 20,000 to 100,000 ng/l, with no response to CRF or cyproheptadine administration. Urinary 5-OH-indolacetic acid was negative. Thoracotomy was performed in July 1985 with resection of two intrapulmonary masses. Histologic study demonstrated a carcinoid tumor, with positive neuron-specific enolase and ACTH immunochemical stain. ACTH concentration in tumoral tissue was 91 pg/g tissue. After surgery ACTH fell dramatically to 37 ng/l, and has remained at this level since then, associated with resolution of the skin hyperpigmentation.

Insulin potentiation therapy: a new concept in the management of chronic degenerative disease

In insulin potentiation therapy the hormone insulin is used as an adjunct in the medical management of the chronic degenerative diseases including malignant neoplasia. In this, the recognized physiological action of insulin--that of increasing cell membrane permeability--is taken advantage of to potentiate the pharmacological actions of medications administered concurrently in the therapy. This potentiation occurs because of the heretofore unrecognized applicability of this membrane permeabilizing effect of insulin to a much wider range of tissues than is classicly accepted, and further the observed effect of this permeabilizing phenomenon as it relates to drug molecules, most importantly the antineoplastic agents. The historical context of insulin potentiation therapy is described, and scientific corroboration for its novel hypotheses is given. Insulin potentiation therapy represents a potentially revolutionary concept in the medical management of diseases and is, in the authors' opinion, deserving of intensive scientific investigation through in vitro and in vivo experimentation and properly conducted human clinical trials in a university teaching hospital setting.

Ectopic G-29 and G-37 glucagon secretion by hypercalcemic infantile renal tumors

Four hypercalcemic infantile renal tumors were shown to secrete glucagon-like peptides. These unusual tumors were histologically classified as rhabdoid tumors of the kidney (3 cases) and a cellular mesoblastic nephroma (1 case). Elevated G-29 and G-37 glucagon levels were detected in the plasma and tumor extracts as well as in the supernatants of cultured tumor explants. Three of these tumors were heterotransplanted into the nude mice and serially passaged from a mouse to another. The glucagon level decreased in the transplanted tumor extracts with the number of passage.

Endocrine carcinoma intermediate cell type of the uterine cervix

Nine cases of endocrine carcinoma, intermediate-cell type of the uterine cervix, were found in a study of 404 cases listed in the files of the University of Texas M. D. Anderson Hospital and Tumor Institute at Houston as adenocarcinoma of the cervix. Based on light microscopic patterns, these cases were divided into pure endocrine carcinoma (six cases), and endocrine carcinoma mixed with adenocarcinoma (three cases). All tumors were 3 cm or larger in at least one dimension. On light microscopic examination, the predominant pattern was trabecular; however, insular, glandular, and spindle patterns were also identified. Argyrophilic granules were demonstrated in all cases by Grimelius stain, and Fontana-Masson (argentaffin) stain was negative. Electron microscopic examination of three cases showed membrane-bound, dense-core granules of the neurosecretory type. Although no endocrine symptoms were found, immunoperoxidase studies demonstrated 5-hydroxytryptamine in seven cases, substance P in three, vasointestinal polypeptide in two, pancreatic polypeptide in one, and somatostatin in one. Clinical behavior of these tumors was extremely aggressive. Although five cases were Stage IB at presentation, two Stage IIB, one Stage IIIB, and one Stage IV, 87.5% of these patients died of their neoplasms within 3 years. This study emphasizes the importance of correctly diagnosing endocrine carcinoma, intermediate-cell type in the uterine cervix, because of the poor prognosis of this tumor when compared with adenocarcinoma of the cervix.

Serotonin-secreting and insulin-secreting ileal carcinoid tumor and the use of in vitro culture of tumoral cells

The authors report the case of a patient with a typical carcinoid syndrome and a severe hypoglycemia due to hyperinsulinism. He was found to have an ileal carcinoid tumor with hepatic metastasis and no evidence of pancreatic insulinoma at surgery and autopsy. By assaying serotonin and insulin in the tumor and in the supernatants of the culture derived from hepatic metastasis, the authors have been able to show that both hormones were produced by the carcinoid tissue. Cultured cells also synthesized minute amounts of gastrin and thyrocalcitonin.

Human mammary and bronchial carcinomas. In vivo and in vitro secretion of substances immunologically cross-reactive with insulin

In the blood of two patients suffering from mammary carcinoma and one from bronchial carcinoma, the levels of substances immunologically cross-reactive with insulin (SICRI) were high before surgery; after surgery normoinsulinemia was restored. Direct evidence of SICRI production by the cultured tumorous tissue is presented. Strong daily SICRI fluctuations were observed, and it is proposed that the fluctuations induce instantaneous hypoglycemias experienced by some tumorous patients.

Hypoglycemia associated with carcinoid tumors. A case report and review of the literature

The authors report a 73-year-old man with a jejunal carcinoid tumor and spontaneous hypoglycemia. Plasma insulin was suppressed (insulin/glucose ratio, 0.2), and nonsuppressible insulin-like proteins (NSILP) were elevated. Seven other patients with carcinoid or related tumors associated with hypoglycemia were found in the literature. Nonsuppressible insulin-like proteins were not measured in these patients.

Ectopic secretion of a growth hormone-releasing factor. Report of a case of acromegaly with bronchial carcinoid tumor

Rarely, acromegaly is produced by neuroendocrine neoplasms elaborating a substance similar to or identical with growth hormone-releasing factor. This report reviews the cases described to date and presents the clinicopathologic features of a patient with acromegaly, mild sellar enlargement, and elevated growth hormone levels associated with a large bronchial carcinoid tumor. Normalization of serum growth hormone levels and regression of acromegaly followed resection of the bronchial tumor, which was shown, by bioassay and immunocytochemistry, to contain a growth hormone-releasing factor.

Immunohistochemical and ultrastructural analysis of bronchopulmonary neuroendocrine neoplasms. I. Carcinoids

Twenty-five strictly defined bronchopulmonary carcinoids were studied by light microscopic immunohistochemistry by the peroxidase technique for NSE (neuron-specific enolase), serotonin, and a broad spectrum of neuropeptides. Eighteen cases were also studied by electron microscopy. Twenty-three of the twenty-five cases showed immunostaining for NSE; 24 cases displayed immunostaining for at least two of the hormones tested for; the single case that failed to show hormonal immuno-reactivity was however positive for NSE and had granules by electron microscopy. Serotonin was the most frequently demonstrated hormone followed by bombesin, vasoactive intestinal peptide, gastrin, leu-enkephalin , alpha-melanocyte stimulating hormone, somatostatin, substance P, and calcitonin. In several cases, adjacent-step sections stained for different hormones strongly indicated immunoreactivity for more than one hormone in single neoplastic cells. By electron microscopy, all 18 cases studied showed generally abundant neurosecretory granules, which, however, displayed considerable heterogeneity in their size, shape, and density. Twelve of these eighteen cases displayed evidence of squamous differentiation and 10 showed characteristic exocrine lumina. The capability of single neuroendocrine tumors and single neuroendocrine tumor cells to produce more than one immunoreactive hormone is hereby amply confirmed; these broad capabilities are certainly reflected in the heterogeneous granule populations seen by electron microscopy. The synchronous presence of squamous and exocrine features in broncho-pulmonary carcinoids indicates that they too are capable of multidirectional differentiation, which should not detract from their being regarded basically as well-differentiated neuroendocrine neoplasms. The clinical significance of strictly defining bronchial carcinoids is underscored by the fact that of 25 cases followed for 2-13 years, only one developed metastases 9 years postoperatively.

Non-endocrine carcinoid tumour of the uterine cervix: aspects of diagnosis and treatment. Case report

A case of primary well-differentiated carcinoid tumour of the uterine cervix in a Chinese woman of 62 years without endocrine symptoms is reported and its clinico-pathological features, ultrastructure and response to radiotherapy discussed. To our knowledge, it is the first of such cases seen in Hong Kong. Clinically, it presented as a polypoid lesion. The initial diagnosis was squamous carcinoma of cervix stage Ib and the patient was treated with radiotherapy. The tumour disappeared after application of first intracavitary irradiation of 4500 mg h. After completion of 9000 mg h, Wertheim hysterectomy followed and no residual tumour was found. Retrospective staining of the pre-irradiation cervical tumour by Grimelius method was positive for argyrophil granules and electron microscopic study demonstrated neurosecretory granules in the cytoplasm and established the diagnosis.

Insulin and glucagon secretion by renal adenocarcinoma

A patient with histologically verified renal adenocarcinoma had dramatic increases in glucagon and insulin levels in plasma and in tumor tissue.

The riddle of tumour hypoglycaemia revisited

In summary, hypoglycaemia due to non-pancreatic tumour is relatively common among the causes of fasting hypoglycaemia in the adult. Most of the neoplasms are large, and present as masses in the mediastinum or retroperitoneal space. Although therapy is difficult, successful palliation by surgery or radiotherapy has been achieved in a number of cases. Although many theories have been advanced to explain the hypoglycaemia, the best documented mechanism is production of an insulin-like substance by the tumour. Both low molecular weight (NSILA-s) and high molecular weight (SNILP) peptides have been reported to be elevated in some cases of tumour hypoglycaemia. Further study of this class of peptides will no doubt lead to assays that may facilitate diagnosis of tumour hypoglycaemia, as well as offer new approaches to the therapy of this disease.

Partial purification and characterization of a peptide with growth hormone-releasing activity from extrapituitary tumors in patients with acromegaly

Growth hormone (GH)-releasing activity has been detected in extracts of carcinoid and pancreatic islet tumors from three patients with GH-secreting pituitary tumors and acromegaly. Bioactivity was demonstrated in 2 N acetic acid extracts of the tumors using dispersed rat adenohypophyseal cells in primary monolayer culture and a rat anterior pituitary perifusion system. The GH-releasing effect was dose responsive and the greatest activity was present in the pancreatic islet tumor. Small amounts of activity were also found in two other tumors (carcinoid and small cell carcinoma of lung) unassociated with GH hypersecretion. Each of the tumors contained somatostatin-like immunoreactivity but the levels did not correlate with the net biologic expression of the tumor. Sephadex G-75 gel filtration indicated the GH-releasing activity to have an apparent molecular size of slightly greater than 6,000 daltons. The GH-releasing activity was adsorbed onto DEAE-cellulose at neutral pH and low ionic strength, from which it could be eluted by increasing ionic strength. The GH-releasing activity was further purified by high pressure liquid chromatography using an acetonitrile gradient on a cyanopropyl column to yield a preparation that was active at 40 ng protein/ml. Partially purified GH-releasing activity, from which most of the bioactive somatostatin had been removed, increased GH release by pituitary monolayer cultures to five times base line. Enzymatic hydrolysis studies revealed that the GH-releasing activity was resistant to carboxypeptidase, leucine-aminopeptidase, and pyroglutamate-amino-peptidase but was destroyed by trypsin and chymotrypsin, indicating that internal lysine and/or arginine and aromatic amino acid residues are required for biologic activity and that the NH2-terminus and CO9H-terminus are either blocked or not essential. The results provide an explanation for the presence of GH-secreting tumors in some patients with the multiple endocrine neoplasia syndrome, type I, and warrant the addition of GH-releasing activity to the growing list of hormones secreted by tumors of amine precursor uptake and decarboxylation cell types.

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.

Norepinephrine-producing tumors of bilateral breasts: a case report

There was a tumor in the left breast which was suspected to be carcinoid tumor at excisional biopsy. Autopsy revealed the same tumor in the right nipple. In the cells of the bilateral tumors a number of argylophil granules were diffusely demonstrated and the neurosecretory ones were verified electronmicroscopically. In the urine of the patient a moderate amount of norepinephrine was excreted. It was presumed that the norepinephrine might have been produced from the breasts. In the literature reviewed, the case of breast carcinoid has not been reported previously.

Carcinoid of the uterine cervix: additional observations on a new tumor entity

Twelve carcinoid tumors of the uterine cervix were studied. Based on the microscopic structure, they were divided into well-differentiated and poorly differentiated types. Both tumor varieties affected adult women. The clinical and gross features of these tumors were indistinguishable from those of invasive squamous cell carcinoma. Of the 12 patients, six died, four with poorly differentiated carcinoid and two with the well-differentiated type. Three patients are alive and symptom-free 9 months to 2 years after treatment; the remaining three were lost to follow-up. Microscopically, four well-differentiated carcinoids showed argyrophil cells, and ultrastructurally two had neurosecretory granules. One of the well-differentiated carcinoids resembled islet cell carcinoma and two had areas resembling medullary carcinoma of the thyroid. The poorly differentiated type of carcinoid had a histologic structure and a cell population very similar to that of the oat cell carcinoma of the lung. Of this group, four were argyrophilic, and by electron microscopy four contained pleomorphic secretory granules. It is considered that these tumors arise from the normal argyrophil cell of the cervix and are part of the group of neoplasms of the diffuse endocrine cell system (APUD).