Pituitary-adrenocortical studies in a patient with Cushing's syndrome induced by thymoma

Neuroendocrine carcinomas (carcinoid, atypical carcinoid, small cell carcinoma, and large cell neuroendocrine carcinoma): current concepts

Neuroendocrine carcinomas are ubiquitous neoplasms that may occur anywhere in the human body. A unifying concept regarding the classification of these tumors has been controversial. Although most neuroendocrine neoplasms occur in the gastrointestinal tract, current concepts regarding classification and nomenclature are being driven by studies of thoracic tumors. One issue that has been put forward to keep separate nomenclatures for these tumors in different organ systems is the different clinical behavior of these neoplasms in different systems. The most important aspect regarding this group of tumors is the fact that they should be considered neoplasms capable of local recurrence and distant metastasis. Close clinical correlation and appropriate treatment are important to improve the survival rate in this group of patients.

Primary neuroendocrine carcinomas of the mediastinum: review of current criteria for histopathologic diagnosis and classification

Primary neuroendocrine neoplasms occurring in the mediastinum are rare. The spectrum of such tumors can range from low- to high-grade neoplasms. The histogenesis of these tumors is varied, and some of them may originate from ectopic tissues in the mediastinum whereas others represent tumors native to the thymus. Primary thymic neuroendocrine carcinomas therefore need to be separated from other neuroendocrine neoplasms of the mediastinum, namely ectopic parathyroid tumors and paragangliomas. The histopathologic classification of primary neuroendocrine carcinomas of the mediastinum is still under debate and continues to be controversial, as is attested to by the different publications on the topic. Some authors continue to use old terms such as "carcinoid" and "atypical carcinoid" to designate these lesions, whereas others favor the use of a more unifying nomenclature that acknowledges the malignant nature of these lesions, namely that of neuroendocrine carcinoma. However, one aspect that all agree on is that, when they occur in the thymic region, these tumors should be considered as aggressive neoplasms capable of local recurrence and distant metastasis. This review will center on the morphologic spectrum of neuroendocrine carcinomas of the thymus, with special emphasis on diagnostic features and criteria for classification.

Primary neuroendocrine carcinoma (thymic carcinoid) of the thymus with prominent oncocytic features: a clinicopathologic study of 22 cases

Twenty-two cases of oncocytic thymic neuroendocrine carcinomas (carcinoid tumors) are presented. The patients were 17 men and 5 women between the ages of 26 and 84 years (median, 55 years). Nine were asymptomatic, and the tumor was found on routine examination; four patients presented with chest pain, two with weight loss, two with multiple endocrine neoplasia I syndrome, and one with Cushing's syndrome. Surgical resection of the mediastinal tumor was performed in all cases. The lesions were described as soft, light tan to brown, measuring from 3 to 20 cm in greatest diameter. On cut section, the tumors showed a homogeneous surface, soft consistency, and focal areas of hemorrhage. Microscopically, the lesions were characterized by nests or trabeculae of tumor cells that contained abundant granular to densely eosinophilic cytoplasm, with round to oval nuclei and in some areas prominent nucleoli. Mitotic figures ranged from 2 to 10 per 10 high-power fields; foci of comedonecrosis were seen in all cases. Immunohistochemical studies including broad spectrum keratin, CAM 5.2, chromogranin, synaptophysin, Leu-7, and p53 were performed in 12 cases. All of the tumors were strongly positive for CAM 5.2 low-molecular-weight cytokeratin, 11 showed strong positive reaction for Leu-7, 10 for broad-spectrum keratin, 8 for chromogranin, 7 for synaptophysin, and only 1 case showed focal positive staining of the tumor cells for p53. Clinical follow-up of 14 patients showed that 10 were alive between 2 and 11 years, and 4 patients had died of tumor from 4 to 11 years after diagnosis. Patients with good clinical outcome were those whose tumors showed low mitotic activity and minimal nuclear pleomorphism, whereas those who had died of their tumors were those whose tumors were characterized by marked nuclear atypia and higher mitotic rates. Oncocytic thymic carcinoids should be added to the differential diagnosis of anterior mediastinal neoplasms characterized by a monotonous population of tumor cells with prominent oncocytic features.

Thymic neuroendocrine carcinomas with combined features ranging from well-differentiated (carcinoid) to small cell carcinoma. A clinicopathologic and immunohistochemical study of 11 cases

We reviewed 11 cases of primary thymic neuroendocrine carcinomas with combined features ranging from well-differentiated to poorly differentiated neuroendocrine carcinoma. For 3 asymptomatic patients, tumors were discovered during routine examination. Presentation in the other patients was as follows: Cushing syndrome, 2 patients; chest pain, 3 patients; superior vena cava syndrome, 1 patient; and hypercalcemia and hypophosphatemia, 1 patient. No clinical data were available for the 11th patient. All tumors were located in the anterior mediastinum and treated by surgical excision. The lesions were large and well-circumscribed with areas of hemorrhage and necrosis. They were characterized by areas showing a proliferation of monotonous, round tumor cells adopting a prominent organoid pattern admixed with areas showing sheets of atypical cells with hyperchromatic nuclei, frequent mitoses, and extensive areas of hemorrhage and necrosis. Immunohistochemical studies performed in 6 cases showed strong CAM 5.2 low-molecular-weight cytokeratin positivity in all cases, chromogranin and synaptophysin positivity in 4, Leu-7 in 3, and focal positivity for p53 in 2. Follow-up information for 9 cases showed that all patients died of their tumors between 1 and 4 years after diagnosis. The present cases highlight the heterogeneity of neuroendocrine neoplasms and reinforce the notion that these tumors form part of a continuous spectrum of differentiation.

Angiomatoid neuroendocrine carcinoma of the thymus: report of a distinctive morphological variant of neuroendocrine tumor of the thymus resembling a vascular neoplasm

Three cases of primary thymic neuroendocrine tumors characterized by prominent angiomatoid features that resembled a vascular neoplasm are presented. The patients were all men between 52 and 59 years of age who presented with chest pain and shortness of breath attributable to a large anterior mediastinal mass. The lesions ranged in size from 6 cm to 15 cm in greatest diameter, and were grossly soft and well circumscribed, but not encapsulated. The cut surface was remarkable for multiple blood-filled cyst-like spaces admixed with focal solid, hemorrhagic areas. Histologically, the tumors contained multiple cystically dilated spaces filled with blood which imparted the lesion with a striking angiomatoid appearance. The walls of the cysts were lined by a monotonous proliferation of round to oval cells with distinct cell borders, round central nuclei, and abundant eosinophilic cytoplasm. Mitotic activity was present in all cases and varied from 3 to 8 mitoses per 10 high-power fields. Immunohistochemical studies performed in two cases showed positivity of the tumor cells for keratin, Leu 7, and synaptophysin, and focal chromogranin positivity in one. Follow-up information obtained in two patients showed that both had died of tumor 4 and 8 years after initial diagnosis. The present cases show an unusual morphological appearance of thymic neuroendocrine tumors that may be mistaken for a vascular neoplasm. Immunohistochemical stains may be of importance in such instances in arriving at the correct diagnosis.

Primary thymic carcinoid with Cushing's syndrome

In a 52-year-old Caucasian man osteopoikilosis had been misdiagnosed roentgenologically 2 years before his death. Gradually he developed Cushing's syndrome and ultimately superior vena caval obstruction. At autopsy a primary thymic carcinoid with extensive osteoblastic bone metastasis was found. Immunohistochemically the tumor was shown to be positive for adrenocorticotropic hormone (ACTH), cytokeratin (KL1), neuron-specific enolase, synaptophysin, chromogranin and glucagon. Remarkably the tumour was negative for serotonin despite high urinary hydroxyindolacetic acid levels. Bilateral hyperplasia of the adrenal cortex was found. The adenohypophysis showed a considerable reduction of ACTH-producing cells and numerous Crooke's cells with a characteristic immunohistochemical pattern.

Evidence for ectopic ACTH production years after bilateral adrenalectomy for Cushing's syndrome: in vivo and in vitro studies

Three patients presented with hyperpigmentation and high plasma levels of ACTH 4-5 years after bilateral adrenalectomy for Cushing's "disease". X-rays and ct-scan of the lungs showed a small pulmonary mass in all. ACTH levels (1100-2000 pg/ml) were not suppressible by high doses hydrocortisone. A carcinoid tumor was removed in two cases and a chemodectoma in the third. Evidence for ACTH secretion by these tumors was provided by both decrease of ACTH levels after surgery and/or in vitro studies. Both carcinoid cultures showed a basal ACTH production, which was clearly increased by LVP (10(-7) M) and CRF (10(-7) M). Our findings in vitro studies suggest the presence of specific receptor sites for physiological stimuli (LVP and CRF) in tumor cell membranes.

Presence of corticotropin-releasing factor-like immunoreactivity in human tumors

Corticotropin-releasing factor (CRF)-like immunoreactivity was measured by radioimmunoassay in human organs and tumors associated with and without ectopic adrenocorticotropic hormone (ACTH) syndrome. It was found to be distributed widely in the stomach, pancreas, adrenal gland, and various tumors (e.g., medullary thyroid carcinoma, small cell carcinoma of the lung, pheochromocytoma, and adenocarcinoma of the gastrointestinal tract and pancreas) in a concentration less than one tenth of that of the hypothalamus. Dilution curves of CRF-like immunoreactivity in tissue extracts paralleled that of synthetic rat (human) CRF. Sephadex G-50 gel filtration showed that a major CRF-like immunoreactivity in tissue extracts coeluted with synthetic rat (human) CRF. Results suggest that a material(s) closely related immunologically to CRF is present widely in normal and tumor tissues outside of the central nervous system.

Thymic hyperplasia and neoplasia: a review of current concepts

Although the term thymic hyperplasia is used most commonly to indicate the occurrence of germinal centers in the thymus, cognizance must be taken of the fact that such centers may occur in apparently normal thymuses in both children and adults. A concept of thymic compartmentalization is proposed with origin of germinal centers in the perivascular space (extraparenchymal compartment) of the thymus. These germinal centers contain a high percentage of B lymphocytes in contrast to the true thymic parenchyma. Although the significance of germinal centers in the thymus parenchyma. Although the significance of germinal centers in the thymus in myasthenia gravis remains controversial, removal of nonneoplastic thymus in this condition is of proven therapeutic value. A variety of neoplasms originating in the thymus have previously been lumped together under the single term "thymoma." It is apparent, however, that thymoma, thymic carcinoid, various lymphomas, and germ cell tumors that arise in the thymus differ not only pathologically but also in their clinical behavior. Thymoma is regarded as an epithelial neoplasm and ultrastucturally is characterized by many desmosomes and tonofilaments. The lymphocytes do not behave in a malignant manner, and lymphomas of the thymus should be sharply separated from true thymoma. Poorly differentiated thymic carcinoma and histiocytic lymphoma may be distinguishable only by the electron microscopic demonstration of desmosomes and filaments in the thymic carcinoma. The evidence that Hodgkin's disease of the thymus ("granulomatous thymoma") is not a variant of thymoma appears overwhelming. Lymphoblastic lymphoma of the thymus is a distinctive neoplasm that is especially prevalent in teenage males. High levels of terminal transferase characterize the lymphoblasts and there is a striking tendency for leukemia to occur. Thymic carcinoid is usually nonfunctional, although one-third of the reported cases are associated with Cushing's syndrome. On light microscopy a ribbon pattern and punctate necroses are characteristic of thymic carcinoids. Electron microscopic demonstration of many dense core granules is invaluable in establishing this diagnosis. An important clue to the diagnosis of thymic seminoma (a neoplasm that shows the same radiosensitivity as its testicular counterpart) is the frequent presence of epithelioid and giant cell granulomas and germinal centers. Separation of the various thymic neoplasms described not only is justifiable on pathologic grounds but is often essential for appropriate patient investigation and treatment.

Cushing's disease in a child with lymphosarcoma and acute leukemia

A 6-year-old girl with lymphosarcoma developed Cushing's syndrome. Suppression-stimulation studies verified adrenal hyperfunction secondary to bilateral adrenocortical hyperplasia, and the course suggested the possibility of "ectopic ACTH" production by the neoplasm as the etiology.

Carcinoid tumors of the thymus

Three patients with carcinoid tumors of the anterior mediastinum are described. Study of these patients and an analysis of previously reported cases indicates that the thymus is the primary site of these tumors, which are probably related to the presence of Kulchitsky cells in normal thymus. These neoplasms differ clinically and anatomically from conventional thymomas. They occur predominantly in men, are not associated with myasthenia gravis or red-cell hypoplasia, and are more aggressive tumors than thymomas. Histologically, they are similar to carcinoid tumors of other organs and differ from the variable combination of epithelial cells and lymphocytes of thymomas. Although they are usually locally invasive and frequently metastasize, the clinical course is usually protracted. It is probable that the reported examples of Cushing's syndrome related to thymomas were actually associated with thymic carcinoid tumors.

[Virilism due to an adrenal medullary tumor with ectopic ACTH syndrome (author's transl)]

The case of a 14-year-old girl with hirsutism and virilism due to the secretion of ectopic ACTH by an adrenal medullary tumor is described. At the age of 5 years changes in appearance had begun with masculinization. The effect of ACTH-like material, measured by radioimmunoassay in plasma and in tumor tissue, was compensated partially by the hypothalamo-pituitary-adrenal feedback mechanism. Increased concentrations of dehydroepiandrosterone, estrone and testosterone in plasma and of 17-ketosteroids and free cortisol in urine originated in the adrenals. After operation of the tumor menarche began spontaneously, hirsutism disappeared and testosterone plasma concentrations returned to normal. An adrenogenital syndrome was excluded.

Syndromes resulting from ectopic hormone-producing tumors

Among the malignant tumors of nonendocrine origin that are capable of producing polypeptide hormones and of manifesting as different endocrine syndromes discussed here are ectopic ACTH syndrome, SIADH, and ectopic gonadotropin-producing tumors.

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.