Calcitonin immunoreactivity in neoplastic and hyperplastic parathyroid glands: an immunohistochemical study

[Neuroendocrine markers in parathyroid tumors]

The parathyroid glands (PTGs) are a key regulator of calcium and phosphorus metabolism in the human body. In terms of their, morphological and immunophenotypic characteristics, PTGs are neuroendocrine organs, and their neoplasms are neuroendocrine tumors. These neoplasms include adenoma and cancer; in addition, glandular hyperplasia may develop, which is most characteristic of multiple endocrine neoplasia (MEN1, MEN2a, and MEN4) syndromes. The morphological characteristics of pathologically altered PTGs in MEN syndromes are variable. The analysis and generalization of knowledge about the features and expression of various immunohistochemical markers in PTG tissue in health and in diseases are useful in the practical work of not only pathologists, but also clinicians of various specialties.

Hereditary Parathyroid Disease: Sometimes Pathologists Do Not Know What They Are Missing

Parathyroid gland excision specimens are common and sometimes underestimated cases that many surgical pathologists encounter regularly. In the vast majority of cases, these will be spot diagnoses of sporadic primary parathyroid adenomas or, perhaps, hyperplasias commonly in the setting of renal failure. However, a small but significant number of parathyroid gland excisions may be due to heritable disease. In most cases, hereditary disease is suspected by the referring clinicians. Nevertheless, a subset of these are undetected which is significant, particularly in the setting of the multiple endocrine neoplasia (MEN), and the hyperparathyroidism jaw tumour (HPT-JT) syndromes. There have been recent advances in recognition of the morphological and immunohistochemical characteristics of these tumours and hyperplasias. While hereditary kindreds are over-represented at specialist referral centres, with awareness of the characteristic clinical and morphological features, the general surgical pathologist is frequently able to suggest the possibility of hereditary parathyroid disease. We therefore provide a succinct guide for pathologists to increase the recognition of hereditary parathyroid disease.

INSM1 is a Sensitive and Specific Marker of Neuroendocrine Differentiation in Head and Neck Tumors

The head and neck is the site of a wide and sometimes bewildering array of neuroendocrine (NE) tumors. Although recognition of NE differentiation may be necessary for appropriate tumor classification and treatment, traditional NE markers such as synaptophysin, chromogranin, and CD56 are not always sufficiently sensitive or specific to make this distinction. Insulinoma-associated protein 1 (INSM1) is a novel transcription factor that has recently demonstrated excellent sensitivity and specificity for NE differentiation in various anatomic sites, but has not yet been extensively evaluated in tumors of the head and neck. We performed INSM1 immunohistochemistry on NE tumors (n=97) and non-NE tumors (n=626) across all histologic grades and anatomic subsites of the head and neck. INSM1 was positive in all types of head and neck NE tumors evaluated here (99.0% sensitivity), including middle ear adenoma, pituitary adenoma, paraganglioma, medullary thyroid carcinoma, olfactory neuroblastoma, small cell carcinoma, large cell NE carcinoma, and sinonasal teratocarcinosarcoma. Notably, it was positive in the vast majority of high-grade NE malignancies (95.8% sensitivity). INSM1 also was negative in almost all non-NE tumors (97.6% specificity) with the highest rates of reactivity in alveolar rhabdomyosarcoma and SWI/SNF related, matrix associated, actin dependent regulator of chromatin, subfamily B, member 1 (SMARCB1)-deficient sinonasal carcinoma. These findings confirm that INSM1 may be used as a standalone first-line marker of NE differentiation for tumors of the head and neck.

Parathyroid: The Pathology of Hyperparathyroidism

This review focuses on the pathologic entities associated with hyperparathyroidism in humans. A discussion of the lesions, their embryology, and pathologic features is included. Immunohistology, cytopathology, and a brief overview of molecular aspects of the lesion are included.

Secretogranin III in human neuroendocrine tumours: a comparative immunohistochemical study with chromogranins A and B and secretogranin II

BACKGROUND

Different epitopes of the granin family of proteins, chromogranin (Cg) A, CgB and secretogranin (Sg) II, have been demonstrated in normal human pancreas, gastrointestinal tract, adrenal medulla and in several neuroendocrine tumours (NETs). SgIII has been recently reported in endocrine pancreas. The aim of the present study was to examine the expression of SgIII in different NETs and compare it with the expression of CgA, CgB and SgII epitopes.

MATERIAL AND METHODS

Tissue specimens from 47 NETs were analyzed. Antibodies to CgA 250-284, CgB 244-255, SgII 172-186 (C-terminal secretoneurin) and SgIII 348-361 were used for immunostaining.

RESULTS

SgIII was expressed in 41 of 47 NETs. The expression of SgIII agreed well with that of CgA, CgB and SgII, with exceptions of phaeochromocytomas, where more CgB and SgII immunoreactive cells were observed and parathyroid adenomas, which were only stained by CgA. In rectal NETs more cells expressed SgIII than CgA.

CONCLUSIONS

This is the first report on SgIII expression in various NETs. A majority of tumours studied displayed SgIII immunostaining, which indicates a functional relationship with the other granins.

The biological characterization of neuroendocrine tumors: the role of neuroendocrine markers

Neuroendocrine tumors (NET) may originate in different organs, from cells embryologically different but expressing common phenotypic characteristics, such as: the immuno-reactivity for markers of neuroendocrine differentiation (defined as "pan-neuroendocrine"), the capacity to secrete specific or aspecific peptide and hormones and the expression of some receptors, that are at the basis of the current diagnostic and therapeutical approach, peculiar to these tumors. NET have been conventionally distinguished in functioning, when associated with a recognized clinical endocrine syndrome, and non-functioning. However, this terminology may be misleading, since the great majority of NET may secrete neuroendocrine peptides, which can be employed as clinical markers for both diagnosis and follow-up. On the other hand, tissue immuno-reactivity for specific hormones does not always reflect secretory activity of the tumor cells. Finally, receptors and genetic markers are acquiring a relevant role in the characterization of NET, both improving knowledge of biology and physiopathology of NET, as well as in developing specific strategies to establish an early diagnosis and targeted therapies, to adopt prophylactic strategies in familial forms, and to identify more efficacious targets for therapy in the future.

Expression of cortistatin and MrgX2, a specific cortistatin receptor, in human neuroendocrine tissues and related tumours

Cortistatin (CST), a novel hormone originally described in the rat, mouse, and human cerebral cortex, displays structural and functional similarities to somatostatin (SRIF). CST binds to all five somatostatin receptors and, differently from SRIF, also binds to MrgX2, which has recently been identified as its specific receptor. Little is known about the distribution of CST and MrgX2 in peripheral non-tumour and neoplastic tissues. The aim of the present study was therefore to determine by immunohistochemistry and mRNA analysis (RT-PCR) the distribution of CST and MrgX2 in 56 human non-tumour and 108 tumour tissues, with special reference to neuroendocrine tissue types. Despite the high level of CST mRNA expression in non-tumour and tumour (both neuroendocrine and non-neuroendocrine) tissues, the presence of immunoreactive CST was confirmed in a subset of gastroenteropancreatic, parathyroid, and pituitary non-tumour cells only, and showed a predominantly focal pattern in most neuroendocrine tumours. Co-localization experiments in the gastroenteropancreatic system demonstrated that the normal CST-producing cells are delta cells, while in the adenohypophysis no preferential co-localization of CST with any of the pituitary hormones was observed. MrgX2 mRNA was variably detected in the hypothalamus, pituitary, thyroid, lung, gastroenteropancreatic tract, testis, and ovary, and was negative in the cerebral cortex, parathyroid, and adrenal, as well as in a variety of tumour types. Conversely, immunolocalization of MrgX2 protein was restricted to neurohypophysis and testis, whilst all tumours analysed were negative. A possible explanation for the discrepancy between RT-PCR and immunohistochemistry is that MrgX2 protein was widely detected in blood vessels, scattered lymphocytes, and gastrointestinal ganglia in both normal and neoplastic samples. The findings demonstrate a selective distribution of CST in normal and neoplastic neuroendocrine tissues, suggesting that CST might have a broader functional role than previously assumed, whereas possible autocrine/paracrine actions via its recently described specific receptor MrgX2 are restricted to selected tissues.