Ectopic ACTH production with autoantibody formation in a patient with acute myeloblastic leukemia

Effects of leukemia inhibitory receptor gene mutations on human hypothalamo-pituitary-adrenal function

BACKGROUND

Stuve-Wiedemann syndrome (STWS) (MIM #601559) is a rare autosomal recessive disorder caused by mutations in the leukemia inhibitory factor receptor (LIFR) gene. STWS has a diverse range of clinical features involving hematopoietic, skeletal, neuronal and immune systems. STWS manifests a high mortality due to increased risk of sudden death. Heterodimerization of the LIFR mediates leukemia inhibitory factor (LIF) signalling through the intracellular Janus kinase (JAK)/STAT3 signalling cascade. The LIF/LIFR system is highly expressed in and regulates the hypothalamo-pituitary-adrenal (HPA) axis.

OBJECTIVES

HPA function was investigated in three STWS patients to characterise consequences of impaired LIF/LIFR signalling on adrenal function.

DESIGN

Six genetically proven STWS patients from four unrelated Turkish families were included in the study. Sudden death occurred in three before 2 years of age. Basal adrenal function tests were performed by measurement of early morning serum cortisol and plasma ACTH concentrations on at least two different occasions. Low dose synacthen stimulation test and glucagon stimulation tests were performed to explore adrenal function in three patients who survived.

RESULTS

All patients carried the same LIFR (p.Arg692X) mutation. Our oldest patient had attenuated morning serum cortisol and plasma ACTH levels at repeated measurements. Two of three patients had attenuated cortisol response (<18 μg/dl) to glucagon, one of whom also had borderline cortisol response to low dose (1 μg) ACTH stimulation consistent with central adrenal insufficiency.

CONCLUSIONS

STWS patients may develop central adrenal insufficiency due to impaired LIF/LIFR signalling. LIF/LIFR system plays a role in human HPA axis regulation.

Cushing's syndrome due to an ACTH-producing neuroendocrine tumour in the nasal roof

A patient with ectopic adrenocorticotrophic hormone (ACTH) production from a neuroendocrine tumour of the nasal roof is presented. By indirect immunoperoxidase techniques the tumour cells were shown to be distinctly positive for ACTH and beta-endorphin but negative for other peptides derived from pro-opiomelanocortin. Neither corticotropin releasing hormone (CRF) found in some tumours associated with ectopic Cushing's syndrome, nor gastrin immunoreactivity, which coexists with ACTH in normal rat pituitary and in rat and human gastrointestinal cells, were demonstrable in the tumour. A review of other, previously recognized locations of CRF/ACTH producing tumours is given to increase the awareness of the ectopic Cushing's syndrome, which may lack the classical features and is characterized by fulminant clinical course, extreme fatigue, weakness, pale facial swelling, oedema and hypokalaemic alkalosis.

Cushing's syndrome secondary to bronchopulmonary carcinoid tumor: report of two cases and literature review

Bronchopulmonary carcinoid tumors have been associated with a variety of endocrine disorders including Cushing's syndrome (CS), which is caused by ectopic adrenocorticotrophic hormone (ACTH) secretion. We report two cases of CS secondary to bronchopulmonary carcinoid tumors. The first patient, a 29-year-old woman, presented hypokalemia, high serum ACTH level and high free-urinary cortisol, raising suspicion of an ectopic ACTH syndrome. Chest computed tomography and Octreoscan showed a peripheral nodule in the left-superior lobe of the lung. After lobectomy, a typical bronchopulmonary carcinoid was diagnosed. The second patient, a 16-year-old boy, presented "moon face" and progressive asthenia, high serum ACTH level and high free-urinary cortisol, raising the same hypothesis. Chest computed tomography and Octreoscan showed a peripheral nodule in the middle lobe. After lobectomy, an atypical bronchopulmonary carcinoid was diagnosed. Both cases had IA stage (T1N0M0), positively immunostaining for chromogranin and ACTH. Neither of these patients had hypophysary microadenomas, adrenal adenomas or recurrence of CS after surgical treatment, demonstrating that CS was caused solely by the presence of the bronchopulmonary carcinoid tumors.

Ectopic pro-opiomelanocortin syndrome

Ectopic POMC syndrome remains one of the most challenging differential diagnoses in endocrinology. Recent progress in the understanding of the tissue specific regulation of POMC gene expression and new insights into the processing of the POMC peptide in nonpituitary tissues has helped elucidate some of the molecular events leading to ectopic expression and secretion of POMC peptides. Corticotropin and other POMC-derived peptides have diverse effects on adrenal steroidogenesis, growth, and extra-adrenal tissues. Differences in POMC gene regulation in the corticotrope versus ectopic POMC-producing tumors provides a scientific framework for the clinical distinction between eutopic and ectopic Cushing's syndrome. In an attempt to revisit recent basic and clinical advances in the diagnosis of ectopic POMC syndrome the authors undertook an extensive literature review of 530 cases in 197 published papers and provided a molecular biologic, demographic and diagnostic update. According to this review, the four most common causes of ectopic POMC syndrome are the small cell carcinoma of the lung (27%), bronchial carcinoids (21%), islet cell tumor of the pancreas (16%), and thymic carcinoids (10%). Although the clinical features of patients with ectopic POMC syndrome are similar to those with Cushing's disease, subgroup analysis reveals a broad spectrum of severity and progression of signs and symptoms of hypercortisolism. The endocrine workup of a patient with suspected ectopic POMC syndrome includes the establishment of pathologic hypercortisolism, diagnosis of corticotropin dependency, and the differential diagnosis of corticotropin-dependent Cushing's syndrome. The use of a variety of baseline endocrine values, dynamic endocrine testing, and invasive procedures leads to the correct diagnosis in the majority of patients with ectopic POMC syndrome. Diagnostic imaging, including conventional radiological techniques and somatostatin receptor scintigraphy, aids in the correct localization and eventual treatment of ectopic POMC production.

Cushing syndrome due to ectopic adrenocorticotropic hormone secretion

Cushing syndrome (CS) caused by ectopic adrenocorticotropic hormone (ACTH) production (EA) poses major challenges diagnostically by mimicking the pituitary-dependent form of CS and therapeutically by producing severe, life-threatening hypercortisolemia. This retrospective follow-up study describes the clinical characteristics and course of EA in a large referral center. Computer-based cross-index codes for EA, CS, and bilateral adrenalectomy were used to identify patients treated at the Mayo Clinic between 1956 and 1998. EA was confirmed in 106 patients. Gender distribution showed a slight female predominance (61:45). Bronchial carcinoid was the most frequent cause of EA (25%), followed by islet cell cancer (16%), small-cell lung carcinoma (11%), medullary thyroid cancer (8%), disseminated neuroendocrine tumor of unknown primary source (7%), thymic carcinoid (5%), pheochromocytoma (3%), disseminated gastrointestinal carcinoid (1%), and other tumors (8%). No tumor was found in 16% of patients. Altogether, 28 patients were managed medically, and the others underwent curative tumor resection (13 patients) or bilateral adrenalectomy (65 patients). Surgically treated patients had longer survival, but this was most likely affected by treatment bias. The diagnoses of CS and ACTH-secreting neoplasm were usually concurrent, although, there were remarkable cases in which the two conditions were diagnosed several years apart. Curative resection of the tumor producing EA was possible in a small proportion of patients (12%). When curative resection is not possible, patients who are reasonable surgical candidates are likely to benefit from adrenalectomy. Additional experience with bilateral laparoscopic adrenalectomy should increase the number of patients who benefit from adrenal-directed surgery.

Expression of pro-opiomelanocortin gene and quantification of adrenocorticotropic hormone-like immunoreactivity in human normal peripheral mononuclear cells and lymphoid and myeloid malignancies

Using Northern blotting with a human genomic DNA probe for the pro-opiomelanocortin (POMC) gene, we have shown specific mRNA in normal human peripheral mononuclear cells (PBMC); the presence of specific mRNA was also observed in a T lymphocyte cell line derived from a patient with lymphoma. We then demonstrated that PBMC translate the message into protein. Thus, using a radioimmunoassay with an antibody for ACTH, a median of 29 pg of ACTH-like immunoreactivity (ACTH-LIR) was found in 10(7) PBMC. ACTH-LIR was also detected in seven different cell lines derived from patients with lymphoid and myeloid malignancies, two of them JM and U937 showing the highest values 135 and 108 pg/10(7) cells, respectively. The chromatographic characterization of this ACTH-LIR showed, at least, three molecular forms of immunoreactive ACTH with molecular weights of the order of 31,000 POMC, 22,000 ACTH, and 4,500 ACTH, in addition to high-molecular-weight material (greater than 43,000). We conclude that PBMC produce ACTH-LIR which may act as a paracrine immunomodulator in a similar way to lymphokines and/or may signal the adrenal gland to secrete glucocorticoids.

Immunocytochemical and ultrastructural findings in a mature retroperitoneal teratoma

Report is made of a mature retroperitoneal teratoma in a 32-year-old man. Investigation of the tumor revealed cells immunoreactive for ACTH, Met-enkephalin, beta-LPH, serotonin, FSH, BPP, S100, Neuron-specific-enolase. These cells were mainly present in the glandular epithelium, lining the cysts of the tumor. Ultrastructurally, neuro-secretory granules were demonstrated in the cytoplasm of the tumoral endocrine cells. At no time did the patient display endocrine symptoms.

Cushing's syndrome

Cushing's syndrome remains one of the most challenging problems in clinical endocrinology. Cushing's disease is caused in the majority of cases by basophil pituitary microadenomas which may be successfully treated by trans-sphenoidal hypophysectomy. Treatment with metyrapone or o,p'-DDD can always induce a clinical remission but not a cure, and neurotransmitter therapy may be effective in a minority of cases. Pituitary irradiation cures about half of cases in the long-term and may be used for surgical failures. Tumours producing ectopic ACTH are frequently benign, small and occult and may produce a syndrome clinically indistinguishable from Cushing's disease. Biochemical investigations cannot absolutely distinguish pituitary from ectopic sources of ACTH and therefore body CT scanning and percatheter venous sampling are essential diagnostic investigations. Tumour localization may result in resection and complete cure, although even small tumours may have a malignant potential. Adrenal tumours are readily diagnosed by plasma ACTH measurement and adrenal CT scanning. Adrenal adenomas are cured by adrenalectomy. Carcinomas may be treated by a combination of adrenalectomy, radiotherapy and o,p'-DDD, but long-term prognosis is poor.

Tumor markers: value and limitations in the management of cancer patients

Sixteen tumor markers are reviewed, and measured to the ideal: produced by the tumor cell alone absent in health and in benign disease present in all patients with a given malignancy level in the blood representative of tumor mass detectable in occult disease. The only marker that approaches the ideal is human chorionic gonadotropin (HCG) in gestational trophoblastic tumors. In this malignancy, the HCG level suggests the diagnosis and stage, confirms response to therapy, and predicts relapse. The three most widely used and intensely studied tumor markers are carcinoembryonic antigen (CEA), alphafetoprotein (AFP), and HCG. CEA cannot be used in screening for cancer, but in carcinoma of the colon its elevation preoperatively increases the likelihood of advanced disease and postoperative recurrence. Postoperatively, elevated titers are often but not invariably associated with recurrent disease. AFP and HCG are useful in the management of nonseminomatous germ cell testicular tumors. Like CEA, they cannot be used for screening. They are more likely to be increased with advancing stage, and after therapy rising levels almost always mean recurrent disease. Some markers are valuable in specific circumstances, such as calcitonin in screening for familial medullary carcinoma of the thyroid. In multiple myeloma, immunoglobulins are useful in determining the tumor mass and response to therapy. In neuroblastoma, catecholamine metabolites are useful primarily in making the diagnosis. In some malignancies, the absence of effective therapy lowers the value of the marker, as for AFP in hepatoma. The remaining markers are too unreliable or too little studied to be useful in the management of an individual patient with cancer. The purpose of this paper is to provide the clinician with an understanding of the limitations of the present tumor markers that will lead to wiser use of the tests, and to provide standards to which future tumor markers should be measured.

Multiple endocrine neoplasia syndromes

The multiple endocrine neoplasia (MEN) syndromes are characterized by autosomal dominant inheritance with a high degree of penetrance but varying expression. This review gives a classification of these syndromes and a short summary of the historical background. The pathogenesis of the disease and its possible origin in the APUD cell system are discussed together with the mechanisms underlying normal and ectopic hormone production by MEN tumors on the basis of recent findings in molecular endocrinology. The natural history and the clinical manifestations of the different syndromes are described. The sensitivity and discriminative capacity of the tests used to detect the syndromes in an early stage are compared. The choice of therapy and criteria for the timing and extensiveness of treatment are also considered. Lastly, problems associated with the ethical and legal aspects of screening, central registration, and monitoring of relatives at risk are described.

Inadequacy of APUD concept in explaining production of peptide hormones by tumours

The amine precursor uptake and decarboxylation (APUD) system of cells has been claimed to derive from the embryological neural crest. This assertion has been uncritically accepted. There is much contradictory evidence, especially about the origin of the gastrointestinal and respiratory APUD cells. There is further evidence that the embryological derivation of a particular cell does not relate to the possibility of ectopic peptide hormone synthesis by malignant tumours arising from that cell type. There are many reports of APUD activity by endodermally and mesodermally derived tumours, and of "APUDomas" with endodermal microscopic features. It seems that the concept of dedifferentiation explains the observed data much more satisfactorily and that the presence of double minute chromosomes may denote gene amplification and cellular production of peptides.