Calcitonin- and ACTH-producing cells in a case of medullary carcinoma of the thyroid. Immunofluorescence investigations

Medullary Thyroid Cancer with Ectopic Cushing's Syndrome: A Case Report and Systematic Review of Detailed Cases from the Literature

Background: Medullary thyroid cancer (MTC) is a neuroendocrine tumor arising from parafollicular C-cells of the thyroid gland that, in rare cases, can cause a paraneoplastic ectopic Cushing's syndrome (ECS). The development of Cushing's syndrome (CS) in MTC patients is generally associated with advanced disease and poor prognosis. Summary: We described a case of severe CS due to MTC in a young male. We performed a systematic review to identify cases of ECS due to MTC. We searched PubMed, Scopus, and Web of Science for publications between database inception and February 2022 and we collected the patient characteristics, disease presentation, employed treatment strategies, and disease outcomes. In addition to our patient, we identified 96 cases of ECS due to MTC reported in literature. Mean age at diagnosis was 44.4 years (range 10-84), and there was a male predominance (male:female [M:F] = 1.8:1). Most patients (51%) presented with metastatic disease at diagnosis and showed severe hypercortisolism. Seventeen patients developed distant metastasis and hypercortisolism during follow-up. Interestingly, in 48% of patients, the diagnosis of CS followed the diagnosis of MTC with a median time of 48 months but, among patients in whom the diagnosis was concomitant (38%), symptoms due to hypercortisolism were frequently the reason for seeking medical advice. Pathology results showed evidence of adrenocorticotropic hormone (ACTH) or corticotropin releasing hormone (CRH) positive cells in 76% of patients in whom they were tested. The management of hypercortisolism was challenging in most patients with 48% requiring, eventually, definitive treatment with bilateral adrenalectomy (BLA). Recently, some limited evidence has emerged regarding tyrosine kinase inhibitors (TKIs) treatment for hypercortisolism in patients with ECS due to MTC. Despite limited information on survival, prognosis was generally poor and the main causes of death were either complications of CS or disease progression. Conclusions: Despite its rarity, MTC should be considered in the differential diagnosis of ECS. Management of hypercortisolism is a key factor to improve the patient's symptoms but it is often challenging and BLA is frequently required. Further studies are needed for investigating the role of TKIs in patients with MTC with ECS.

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.

The Pathology of Medullary Carcinoma of the Thyroid: Review of the Literature and Personal Experience on 62 Cases

The aim of the present review is to analyze the numerous pathological patterns of medullary carcinoma of the thyroid (MCT) and discuss the problems of differential diagnosis with other thyroid and nonthyroid tumors. In addition, morphological parameters and phenotypic features were related to the clinical outcome. The recent literature was reviewed and compared with the features of 62 MCTs observed at our institution. The most common patterns of growth are trabecular, alveolar and spindle cells, but MCT can mimic virtually all other primary thyroid tumors and some nonthyroid neoplasms. This heterogeneity has no proven implications for prognosis, but is of relevance for diagnostic purposes, as the differential diagnosis of MCT can be difficult in nonclassical cases. In agreement also with the literature data, no relationship between histopathological parameters and outcome was found in our series, although clinically aggressive tumors had a more advanced stage at presentation. Immunocytochemica demonstration of calcitonin is apparently the only valid criterion for a correct typing of MCT. Chromogranin A is an additional sensitive marker of MCT and parallels calcitonin expression in the majority of cases.

Diagnostic problems in medullary carcinoma of the thyroid

Medullary carcinoma of the thyroid (MCT), the tumor entity related to parafollicular C cells of the thyroid gland, is characterized by peculiar morphological, functional and behavioral features. Apart from the constant finding of calcitonin production by MCT, heterogeneous patterns of growth as well as different associations with other lesions in the setting of MEN II syndrome have been observed. This review addresses these points, as were discussed at the 1992 European School of Pathology courses. Heterogeneity of histological patterns of MCT suggests caution in the interpretation of any thyroid tumor. Immunohistochemical demonstration of calcitonin is apparently the only valid criterion for a differential diagnosis. A correct identification of MCT is important for the individual patient (to plan proper therapy) but also for patient's relatives to screen other familiar cases in the setting of MEN II syndromes.

Medullary carcinoma of the thyroid as a cause of Cushing's syndrome: a case with ectopic adrenocorticotropin secretion characterized by double enzyme immunostaining

A case of a medullary carcinoma of the thyroid gland that secreted both calcitonin and adrenocorticotropin (ACTH) is reported. The patient was a 32-year-old man who was referred to the Clinical Center of the National Institutes of Health with radiologic evidence of intrathoracic and hepatic masses accompanied by florid Cushing's syndrome. Serum levels of calcitonin and ACTH were elevated. The thoracic and hepatic masses were resected. The histologic findings were typical of medullary carcinoma of the thyroid with extensive metastases to the liver. The neoplasm had a predominantly solid pattern, and the neoplastic cells were either round or spindled, many with cytologic atypia. Immunohistochemical analysis of fixed, paraffin-embedded sections demonstrated chromogranin, calcitonin, and ACTH in the neoplastic cells. The immunostaining for chromogranin was intense in all of the cells, whereas weaker staining for calcitonin and ACTH was present in scattered cells. Electron microscopy revealed sparse secretory granules in the majority of tumor cells; a minority of neoplastic cells contained numerous granules. We further characterized this neoplasm by performing dual immunohistochemical analysis. This technique clearly demonstrated the presence of ACTH and calcitonin within the same neoplastic cells. Thus, the medullary carcinoma of the thyroid in this patient was the source of ectopic ACTH secretion causing Cushing's syndrome. In addition, this report highlights the value of using double immunostaining to localize both the ACTH and calcitonin within the same cells.

The utility of some modern techniques in understanding thyroid pathology

A number of evaluating techniques have moved from the research laboratory into the purview of the diagnostic pathologist and have been applied to the analysis of thyroid lesions. Some of these have already proved diagnostically and prognostically useful, whereas some have produced insights into pathogenesis of specific thyroid lesions and disorders. Rapid proliferation and application of these techniques should allow for increased understanding of human thyroid disease in the near future.

C cell carcinoma of the thyroid. Follicular variant

A case of C cell carcinoma of the thyroid with an unusual follicular growth pattern of the cancerous C cells is described. The primary tumor consisted of a mixture of medullary and follicular features while the metastatic foci in the lymph nodes and liver displayed only a medullary arrangement. Histochemical study disclosed numerous argyrophilic cells in both the follicular and medullary parts. These cells were immunohistochemically positive for calcitonin, calcitonin gene-related peptide (CGRP) and other peptides as well as carcinoembryonic antigen (CEA), but negative for thyroglobulin. Radioimmunoassay done on the tissue extract revealed a high content of calcitonin. Electron microscopy showed small intracytoplasmic secretory granules and, in the follicular lining cells, formation of microvilli. A minor component consisting of glandular structures has been reported in medullary carcinoma of the thyroid, suggesting a potentiality for glandular differentiation of the C cells. In equivocal cases, immunohistochemical examination for calcitonin and thyroglobulin is essential for accurate diagnosis of thyroid carcinoma.

Mucosubstances in medullary carcinoma of the thyroid

We have studied mucosubstances in 12 cases of medullary carcinoma of the thyroid using histochemical techniques and a number of different lectins. Immunohistochemical staining for calcitonin and carcinoembryonic antigen was also performed. We have found that the presence of mucosubstances is a constant finding in medullary carcinomas; they were present extracellularly in 100% of cases and intracellularly in 53.3%. In both these compartments there was a predominance of neutral over acid mucosubstances. Receptors for UEA-I, Con A, RCA-I, Succ-WGA and SBA were found in many cells in the majority of cases, but there were differences in the affinity from one case to another. Because of this lack of specificity lectin histochemistry is not of diagnostic value in medullary carcinomas of the thyroid. The possible relationships of the lectin-binding results to glycosylated hormone precursors and carcinoembryonic antigen are discussed.

Epithelial markers in thyroid carcinoma: an immunoperoxidase study

Ten cases each of papillary, follicular, anaplastic and medullary carcinoma of the thyroid were stained for thyroglobulin, calcitonin, epithelial membrane antigen (EMA), carcinoembryonic antigen (CEA) and cytokeratin (CAM 5.2). Monoclonal or affinity purified polyclonal antibodies, and an indirect immunoperoxidase technique were used. All the papillary and follicular tumours, 5/10 anaplastic and 3/10 medullary carcinomas contained thyroglobulin. Only the 10 medullary carcinomas stained positively for calcitonin. Three out of 10 papillary, 1/10 follicular, 0/10 anaplastic and 10/10 medullary carcinomas were positive for CEA. Nine out of ten papillary, 7/10 follicular, 2/10 anaplastic and 3/10 medullary carcinomas were positive for EMA. Ten out of 10 papillary, 10/10 follicular, 5/10 anaplastic and 10/10 medullary carcinomas were positive for cytokeratin. The presence of calcitonin and CEA is of value in the diagnosis of medullary carcinoma, and enable its distinction from anaplastic thyroid carcinoma. Thyroglobulin is a useful marker in thyroid carcinomas.

The value of immunohistochemistry in medullary thyroid carcinoma: a systematic study of 30 cases

Thirty cases of medullary thyroid carcinoma were investigated by immunoperoxidase staining techniques to evaluate the diagnostic significance of neuron-specific enolase (NSE), carcinoembryonic antigen (CEA), somatostatin (SOM), a-subunit of human chorionic gonadotrophin (a-hCG), serotonin (5-HT) and adrenocorticotropic hormone (ACTH) immunoreactivity as diagnostic markers in comparison to different calcitonin (CT) staining patterns. Twenty three cases exhibited a strong (group I) or moderate (group II) staining intensity for CT and did not need further immunocytochemical proof for classifying them as medullary carcinoma. From seven cases which showed only a weak or borderline CT-immunoreactivity (group III), six stained positively for NSE and four positively for CEA. SOM-positive cells were identified in six cases and a-hCG or 5-HT-positive cells respectively in three cases of group III. Twenty follicular and 20 papillary carcinomas also included in this study did not react with any of the above mentioned antibodies. Therefore, NSE and CEA represent useful additional diagnostic markers particularly for the identification of medullary carcinoma with weak or borderline CT-immunoreactivity. The identification of other peptides may also be helpful in demarcating it from thyroid tumours of follicular cell origin.

Medullary carcinoma of the thyroid gland: an immunocytochemical study

Twenty-seven cases of medullary carcinoma of the thyroid gland (MCT) were studied by light microscopy, immunocytochemistry, and electron microscopy. Immunoreactivity for neuron-specific enolase (NSE) and calcitonin was present in all tumors. The numbers of peptides and serotonin demonstrated in each case varied from one to eight. Bombesin was present in 18 of the 27 cases, serotonin in 15, leu-enkephalin in 8, somatostatin in 8, gastrin in 3, substance P in 1, vasoactive intestinal peptide (VIP) in 1, and ACTH in 1. Insulin and glucagon were not encountered in any of the tumors. Immunoreactivity for thyroglobulin was seen in five primary tumors as well as in one lymph node metastasis. The finding of concurrent production of calcitonin and thyroglobulin within the same tumor is enough to question the dogma of the separate origin of follicular cells and C-cells. We were unable to attach any clinical importance to the production of multiple peptides and/or amines.

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.

Plasma calcitonin and ACTH responses to lysine vasopressin, calcium and pentagastrin in a patient with medullary thyroid carcinoma associated with Cushing's syndrome

In a case study of medullary thyroid carcinoma (MTC) associated with Cushing's syndrome, elevated levels of urinary 17-hydroxycorticosteroids, plasma ACTH, cortisol, calcitonin (CT) and somatostatin (GHRIH) were documented. Lysine vasopressin administration further increased the levels of plasma ACTH, cortisol and CT, whereas the administration of calcium and pentagastrin increased only the level of plasma CT. Immunoreactive ACTH, CT and GHRIH were highly concentrated in the tumour tissues. Basal plasma ACTH levels were more progressively increased than plasma CT during the postoperative course when the patient was treated with o,p'-DDD, since the tumour was not completely resected. These findings suggest that the secretion of ACTH and CT from MTC were regulated in a different manner.

Production of gastrin releasing peptide by medullary carcinoma of the thyroid. An immunohistochemical study

Forty medullary carcinomas of the thyroid (MCT) with documented calcitonin (CT) production were studied immunohistochemically for the production of gastrin releasing peptide (GRP), a mammalian counterpart of amphibian bombesin. GRP-positive cells, revealed by an unlabelled peroxidase-antiperoxidase immunoenzyme histochemistry were found in 81% (34/40) of the MCTs. Variable numbers of tumor cells in positive MCTs were immunostained for GRP. In 3 cases with Sipple's syndrome, cells in scattered microscopic MCT nodules and hyperplastic intrafollicular C cells of the thyroid were frequently positive for GRP as well as for CT. Non-neoplastic C cells (or CT-positive cells) of the human thyroids were also positive for GRP. In the neoplastic and non-neoplastic C cell system, some cells were confirmed to be immunoreactive with both anti-GRP and anti-CT. All these findings indicate that GRP and CT are closely associated peptide hormones produced by the C cell system.

Calcitonin, somatostatin and ACTH immunoreactive cells in a case of familial bilateral thyroid medullary carcinoma

Bilateral medullary carcinoma of the thyroid (MCT) was discovered in a symptomless patient of a high-risk MCT family. Raised serum calcitonin responding abnormally to pentagastrin led to a thyroidectomy. Grossly, the thyroid showed one nodule in the upper third of each lobe. Light microscopy revealed typical MCT with amyloid deposits. Nontumoral thyroid tissue showed C cell parafollicular hyperplasia. Electron microscopy detected intracellular secretory granules (mean diameter, 150 nm) and typical amyloid fibrills. Immunochemistry revealed numerous calcitonin immunoreactive cells in the nodules, in normal para and intrafollicular C-cells and hyperplastic C-cells. Somatostatin and ACTH were detected in certain tumor cells, but not in normal and hyperplastic C-cells. MCT hormonal production potential is discussed.

Medullary carcinoma of the thyroid with ectopic ACTH syndrome

An autopsied patient with medullary carcinoma of the thyroid and ectopic ACTH syndrome is reported. A microadenoma of pancreatic islet coexisted in this case, which is assumed to be of D cell origin. Immunohistochemical study revealed decreased number of pituitary ACTH cells. Some of them showed Crooke's degeneration. Hormone assay study of tumor tissue and plasma disclosed abnormal ACTH, beta-MSH as well as calcitonin. Somatostatin and Substance P were also demonstrated in tissue. Histologically the tumor showed solid alveolar pattern with a minor part consisting of small cell variant and this histologic variation is discussed.

ACTH-secreting medullary carcinoma of the thyroid: monitoring of clinical course with calcitonin and cortisol assays and immunohistochemical studies

The clinical course of a patient with Cushing's syndrome secondary to metastatic medullary carcinoma of the thyroid was documented with serial calcitonin and cortisol assays and tumor immunohistochemistry studies. Cortisol levels were originally markedly elevated but returned to normal after total thyroidectomy. These levels rose again when the patient developed liver metastases but normalized during chemotherapy, never to rise again despite the appearance of cervical lymph node metastasis. Calcitonin levels remained elevated throughout the course. The original tumor was composed of two cell lines: one containing both calcitonin and ACTH and another containing only calcitonin-reacting cells. However, the cervical metastasis showed a marked decrease in both cell lines with fever than 1% of cells reacting to ACTH, and only 25% to calcitonin. The almost total disappearance of ACTH-reacting cells may have been therapeutically induced or may represent a consequence of tumor progression.

Relationship of metastatic medullary thyroid carcinoma to calcitonin content of pheochromocytomas: an immunohistochemical study

Immunoperoxidase studies have been utilized to investigate further the previously reported presence of immunoassayable calcitonin in pheochromocytoma tissue from some patients with MEN II syndromes. We have been able to demonstrate calcitonin in pheochromocytoma tissue only in two patients with MEN II syndromes in whom the pheochromocytomas contained metastatic medullary thyroid carcinoma. In both cases, the calcitonin was present only in the medullary carcinoma. We have not been able to demonstrate immunoreactive calcitonin in normal adrenal glands or in pheochromocytomas of other patients with and without MEN syndromes. Adrenal medullary cells and thyroid C cells are both of neural crest origin and both possess APUD characteristics. The presence of calcitonin in medullary thyroid carcinoma cells and not in pheochromocytes has important implications with regard to cellular differentiation and peptide hormone production.

Electron and immunoelectron microscopic study of thyroidal medullary carcinoma

A correlated light, immunofluorescent, electron and immunoelectron microscopic study on the histogenesis and immunochemical nature of the tumor amyloid in medullary carcinoma of thyroid (MCT) was performed. The light microscopic finding of cytoplasmic inclusions in tumor cells was related ultrastructurally to a unique form of cellular degeneration composed of particulate and fibrillar matters, which could be the precursor of amyloid deposits. The immunofluorescent staining revealed calcitonin in tumor cells and in portions of amyloid. Ultrastructurally, the storage granules were morphologically heterogeneous and contained variable amount of immunoreactive calcitonin. Immunoelectron microscopy demonstrated disintegration of the granules with apparent discharge of calcitonin into the matrix of the above-mentioned particulate and fibrillary mass. Immunoreactive calcitonin was not shown on the mature amyloid fibrils nor in most of the granular matters closely associated with the amyloid. The results indicate that the amyloid in MCT, though related to the secretory products of the tumor cells, may not represent the hormonally active calcitonin molecule.

Demonstration of argyrophil granules in small cell carcinoma of the lung

The Grimelius silver nitrate stain has enabled us to demonstrate the presence of tumor cells with argyrophil granules (argyrophil cells) in small cell carcinoma of the lung. Of the 22 tumors, 11 showed varying numbers of argyrophil cells. The occurrence of the cells differed in frequency among the subtypes of small cell carcinoma. The fusiform cell type showed the cells more frequently than the other types. Both tumors with numerous argyrophil cells belonged to the fusiform cell type. The number of positive cells seen under the light microscope did not correlate with the number of cells containing neurosecretory granules under the electron microscope, nor with the amount of either ACTH or serotonin in the tumor extracts. The demonstration of these cells in a pulmonary carcinoma may be of help in making correct histological diagnosis.

Production of several substances by medullary carcinoma of the thyroid

Two patients with the typical morphology of medullary carcinoma of the thyroid are reported. Biochemical analysis of the tumor tissue demonstrated the presence of calcitonin, ACTH and MSH, although symptoms referable to these hormones were hardly manifested. Serum CEA levels were elevated and CEA immunofluorescences in the tumor cells were positive. Moreover, in one patient, serotonin concentration was raised in the tumor tissue, and gastrin level was also elevated in the peripheral blood. These results suggest that the tumors may produce several substances.

Multiple endocrine cell types in thyroid medullary carcinoma. Evidence for calcitonin, somatostatin, ACTH, 5HT and small granule cells

10 cases of thyroid medullary carcinoma (TMC) have been studied ultrastructurally and histochemically. Well differentiated calcitonin-producing C cells were present in all tumours, being prevalent in 9 cases. 5-Hydroxytryptamine (5HT) storing cells were found in two cases, somatostatin immunoreactive cells in at least 5 cases and ACTH-immunoreactive cells in 4 cases. Ultrastructurally, at least 3 types of apparently non-C cells were observed. Type 1 cells with large, poorly osmiophilic granules resembling those of gastroenteropancreatic D cells, were present in 6 cases; they appeared to correlate well with somatostatin immunoreactive cells. Type 2 cells with large osmiophilic granules were found in 5 cases; they resembled ACTH-MSH cells of the human pituitary and may correspond to the ACTH-immunoreactive cells of light microscopy. Type 3 cells with small granules and an unknown function were found in 6 cases, always in scarce number. It is concluded that TMC, although mainly made up of C cells, usually contains large proportions of other endocrine cell types.

Immunohistological study on the ACTH producing islet cell carcinoma of the pancreas

ACTH producing cells in islet cell carcinoma associated with Cushing's syndrome were studied by an improved immunoperoxidase as well as immunofluorescence technique. The cells which contained ACTH antigen were distributed throughout the tumor tissue of both primary and metastatic lesions in rather small numbers. In the small cancer nests they were present in an irregular or mosaic pattern and, on the contrary, they tend to line along the margin in the larger nests. The intracytoplasmic localization of the ACTH antigen was characteristically demonstrated in the infranuclear area of the tumor cells, closely simulating that of the argentaffin granules of the enterochromaffin cells. The electron microscopic observation identified membrane enclosed, cored granules, 200-300 nm in diameter, present in clusters in the infranuclear area of some tumor cells, which were considered corresponding well to the ACTH positive cells in immune staining.

Medullary carcinoma of the thyroid. Diagnostic problems

Light microscopy is usually considered sufficient for the diagnosis of medullary carcinoma of the thyroid (MCT). As stromal amyloid is not always present and the tumor may exhibit great variation in growth pattern, light microscopy alone, however, may lead to misinterpretations. Of 1670 thyroid carcinomas registered durging a 15-year period in Norway, 42 were originally interpreted as MCT. The slides were reviewed and the diagnosis maintained in 33 cases only. Twenty-four additional cases were found by reviewing histopathologic slides from neoplasms originally registered as other types of thyroid tumors. Of 57 cases of MCT, stromal amyloid was demonstrated in 43. Calcitonin measurements and electron microscopy, even on formalin-fixed material, were valuable aids in establishing the correct diagnosis, though none of these methods are unequivocal. Different aspects of the problems concerning the diagnosis of MCT are discussed through the detailed presentation of five patients.