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S L Asa

Publications and source records attributed to S L Asa.

At least 91 records · Page 5Linked to original sources
PubMed1995

Are activating mutations of the adrenocorticotropin receptor involved in adrenal cortical neoplasia?

The objective of this study was to investigate the presence of activating mutations of the ACTH receptor gene in benign and malignant adrenocortical tumours. Genomic DNA was extracted from a variety of adrenocortical neoplasms from 16 patients and the entire ACTH receptor gene was then amplified by the polymerase chain reaction and sequenced. No mutations were detected within the coding region of the ACTH receptor gene in the 16 adrenocortical tumours studied. It is likely that mutations of the coding region of the ACTH receptor gene do not play a major role in adrenocortical tumourigenesis.

Adenoma↗
PubMed1995

Management considerations in Hürthle cell carcinoma.

BACKGROUND: Hürthle cell tumors still pose issues concerning diagnosis and management. METHODS: From 1984 to 1993 forty-seven patients underwent thyroidectomy, and they were diagnosed after operation to have presumptive Hürthle cell tumors. The surgical pathologic findings were reviewed. In the neoplastic group the chart was reviewed for clinical features and outcome. RESULTS: Thirty-one patients had nonneoplastic Hürthle cell nodules. Eleven (69%) of the 16 tumors were malignant affecting 11 women and five men ranging in age from 22 to 86 years. Two patients died of cancer for a 18% rate; one patient is alive with disease. Operations were uncomplicated. Factors for adverse outcome include tumor size greater than 4 cm, woman older than 60 years of age, and complete capsular invasion on surgical pathologic findings. CONCLUSIONS: Fine-needle aspiration biopsy demonstration of Hürthle cell lesion is an indication for operation, providing Hashimoto's thyroiditis is excluded. Our surgical practice (I.B.R.) is to perform total thyroidectomy for all Hürthle cell neoplasms, as well as jugular node sampling and adjuvant radioiodine for cancer. Stringent histologic interpretation is possible and necessary for true appreciation of Hürthle cell tumor incidence and behavior. Cancer mortality of 18% is greater than the rate (2%) of our well-differentiated thyroid cancer group.

Adenoma, Oxyphilic↗
PubMed1995

Gangliocytomas of the sellar region--a review.

Gangliocytomas are benign, slow growing neuronal tumors and are found for the most part in children and young adults. They are most often localized in either the spinal cord or the cerebral hemispheres. Gangliocytomas in the sellar region are extremely rare and only 43 such tumors (including 4 own cases) have ever been described in the literature. Although these tumors are genuine rarities without any epidemiological importance, they do provide some interesting information on tumorigenesis of pituitary adenomas: 65% of the sellar gangliocytomas are associated with a pituitary adenoma. 74% of patients with these tumors suffered hormonal oversecretion of at least one of the pituitary hormones (mostly growth hormone). With only one exception, the hypothalamic releasing hormone corresponding to the hormonal oversecretion syndrome could be demonstrated in the gangliocytoma immunohistochemically. Ultrastructural studies could demonstrate close cell to cell contacts between adenoma and gangliocytome cells. All these data support the hypothesis that chronic overstimulation by hypothalamic releasing hormones play a role in the development of hormone secreting pituitary adenomas. However, in contrast to sellar gangliocytemas, extrahypothalamic tumors secreting excessive hypothalamic hypophysiotropic hormones have never been associated with a pituitary adenoma. They have only been associated with pituitary cell hyperplasia. Therefore, the hypothesis can be made that hypothalamic releasing hormones only promote but do not initiate tumorigenesis of pituitary adenomas.

Adult↗
PubMed1995

Expression of growth factors and growth factor receptors in normal and tumorous human thyroid tissues.

A number of growth factors have been implicated as stimuli of thyroid cell proliferation; overexpression of these growth factors and/or their receptors may play a role in the growth of thyroid tumors. To determine if immunohistochemical detection of growth factors and/or their receptors correlates with morphological alterations in proliferative lesions of thyroid, we examined the localization of epidermal growth factor (EGF), transforming growth factor-alpha (TGF-alpha) and their common receptor, EGF-receptor (EGF-R), insulin-like growth factor-1 (IGF-1), IGF-1-receptor (IGF-R) and IGF binding proteins (IGFBP)-1, -2, -3, and -4, nerve growth factor (NGF), and its receptor NGF-receptor (NGF-R), transforming growth factor-beta (TGF-beta), and basic fibroblast growth factor (bFGF), in normal thyroid tissue and various thyroid tumors. We applied the streptavidin-biotin technique to formalin-fixed, paraffin-embedded tissues. We studied 8-16 different cases of each of the following: normal human thyroid, multinodular hyperplasia, follicular adenoma, papillary carcinoma, follicular carcinoma, medullary carcinoma, and anaplastic carcinoma. EGF, TGF-alpha, and their receptor EGF-R were widely expressed in normal thyroid and in all the thyroid lesions examined. IGF-1 and IGFBP-1 were diffusely present in all different thyroid tissues as well. There was no difference in staining intensity or distribution that correlated with the pathological process. IGFBP-4 seemed to have a variable expression. IGFBP-2 and -3 were detected only in medullary carcinomas.(ABSTRACT TRUNCATED AT 250 WORDS)

Carrier Proteins↗
PubMed1995

Clonality of thyroid nodules in sporadic goiter.

Clonality studies have suggested that neoplasms are monoclonal and hyperplasias are polyclonal. To investigate this question in thyroid, we analyzed the clonality of 26 morphologically characterized hyperplastic nodules from 19 patients with sporadic goiters. For comparison we studied six thyroid carcinomas. We used the highly informative M27 beta probe that maps to the X-chromosome DXS255 locus (X cen-p11.22). Material was obtained from 52 nodules; tissue from nine nodules was rejected because of contamination with normal elements, five patients (eight nodules) were homozygous at Pst I sites in nonnodular thyroid tissue, and three nodules were excluded for technical reasons. Methylation patterns after Hpa II digestion confirmed polyclonality in all nontumorous thyroids of informative patients. Seven hyperplastic nodules were polyclonal, and 18 were monoclonal; one showed loss of heterozygosity. One nodule exhibited aberrant methylation. Multiple nodules were obtained from four patients; in three, all were monoclonal with activation of the same allele. Three papillary carcinomas were monoclonal; two exhibited aberrant methylation. One follicular carcinoma showed loss of heterozygosity. Our data indicate that morphologically indistinguishable hyperplastic thyroid nodules may be monoclonal or polyclonal. These findings suggest that variable molecular mechanisms are involved in the pathogenesis of nodules in sporadic goiter. Future studies will need to explore the biological significance of nodules of variable clonal origin.

Adult↗
PubMed1995

Mammosomatotroph adenoma causing gigantism in an 8-year old boy: a possible pathogenetic mechanism.

The pathophysiology of mammosomatotroph adenomas remains unclear. We studied a mammosomatotroph adenoma removed from an 8-year old boy with a 5-year history of growth acceleration and acromegalic gigantism at presentation. Elevated basal GH (mean 28 micrograms/l) and PRL (mean 120 micrograms/l) plasma levels were observed, as well as paradoxical responses of GH to L-dopa, TRH and oral glucose administration; PRL was reduced by L-dopa and slightly increased by TRH; GHRH stimulated release of both GH and PRL. Two operations were required to remove the very large tumour and the patient was treated with bromocriptine before the second. Hormonal secretion by tumour explants in culture was evaluated under basal conditions and after stimulation or inhibition. High levels of GH and PRL were secreted for up to 24 days. Furthermore, GHRH and TRH caused a dose-related stimulation of both hormones, while somatostatin and dopamine were effective in suppressing either basal or stimulated hormone release only at very high (microM) concentrations. Intracellular events were studied by determination of the guanosine triphosphate binding (G) protein levels and adenylate cyclase (AC) activity in the tumour tissue. Before bromocriptine treatment, AC activity was very high in the tumour and could be further stimulated by various agents; very high levels of the AC-stimulatory G protein alpha subunit Gs alpha and very low amounts of the AC-inhibiting G protein alpha subunit Gi3 alpha and of the phospholipase C-stimulating G protein alpha subunit Gq alpha were found in the tumour. After bromocriptine, baseline AC activity was normalized and could no longer be stimulated; Gs alpha and Gi3 alpha levels were unchanged while those of Gq alpha were normalized. Screening of tumour DNA after amplification by polymerase chain reaction followed by single-strand conformational polymorphism analysis did not reveal any mutations in the hot spots of G protein alpha subunits (alpha s, alpha i2, alpha o2 and alpha 11) genes or in the H-ras and p53 genes. Gs alpha and GH transcription factor-1 (pit-1) expression were evaluated by amplification of cDNA. While the mRNA expression of pit-1 decreased after bromocriptine treatment, that of Gs alpha increased. These data suggest the possibility of an oncogenic process involving overexpression of Gs alpha, resulting in chronic activation of adenylate cyclase. Furthermore, our results suggest that the anti-secretory and anti-proliferative effects of bromocriptine may be mediated through a decrease in Pit-1 secondary to the inhibition of adenylate cyclase activity.

Adenoma↗
PubMed1995

Targeting of transforming growth factor-alpha expression to pituitary lactotrophs in transgenic mice results in selective lactotroph proliferation and adenomas.

The PRL-secreting cells of the pituitary gland normally express transforming growth factor-alpha (TGF alpha). To determine the effect of increasing TGF alpha expression in the pituitary, a transgenic mouse model was created in which overexpression of human TGF alpha was directed to the pituitary lactotrophs using the rat PRL promoter. Of the four gene-positive mouse lines, two expressed the messenger RNA corresponding to the transgenic in the pituitary glands. However, in both these lines, expression could only be detected in the female animals. Expression of the transgenic could be detected as early as 1 month of age, but no pathology or developmental abnormalities were detected until the animals reached 6 months, at which time, hyperplasia of the lactotrophs. By the age of 12 months, all of the homozygous transgenic females had developed pituitary adenomas that were immunopositive for PRL. The other hormone-producing cells of the pituitary showed no obvious pathology. The male transgenics developed neither hyperplasia nor adenomas, nor did the gene-positive transgenic lines that did not express the transgene. In no case was an aggressive pituitary tumor seen. This transgenic mouse model indicates that TGF alpha overexpression by lactotrophs stimulates the growth of these pituitary cells. Furthermore, TGF alpha has a highly localized action in the pituitary gland, resulting only in lactotroph hyperplasia and prolactinomas. These observations suggest that TGF alpha might play a role in the development of prolactinomas.

Animals↗
PubMed1995

Cell-specific expression of estrogen receptor in the human pituitary and its adenomas.

Estrogen affects the synthesis and release of several pituitary hormones. The estrogen receptor (ER), a member of the steroid hormone receptor family, is thought to mediate transcriptional effects in a cell-specific fashion. We investigated whether ER is expressed in specific hormone-producing cell types in the human pituitary and its adenomas. Pituitary adenomas (n = 34) were collected at the time of surgery, and normal glands were obtained from autopsy. Expression of ER messenger ribonucleic acid (mRNA) was determined by reverse transcription-polymerase chain reaction (RT-PCR) and in situ hybridization. ER was also localized with immunohistochemistry and protein extraction. By RT-PCR, ER mRNA was found in the nontumorous pituitary and in pituitary adenomas expressing only PRL, in those producing GH and PRL, and in adenomas expressing the gonadotropic hormones. No ER mRNA was detected in adenomas expressing only GH without PRL or gonadotropins, nor in tumors producing ACTH without PRL or gonadotropins. In situ hybridization was not as sensitive or specific as RT-PCR. Biochemical analysis performed on seven tumors that were positive for ER mRNA by RT-PCR detected ER protein in only one PRL adenoma and one oncocytoma and yielded negative or equivocal results in one PRL adenoma, three GH-PRL adenomas, and one null cell adenoma. ER protein was localized by immunohistochemistry in scattered cells of the nontumorous adenohypophysis and in a few PRL and gonadotroph adenomas. We conclude that ER expression, as determined by RT-PCR, correlates with the expression of PRL or gonadotropins; in contrast, ER mRNA was not detected in adenomas that express only GH or ACTH. These findings implicate ER as a cell-specific transcription factor that may regulate cytodifferentiation in the pituitary.

Adenoma↗
PubMed1995

Membrane-anchored expression of transforming growth factor-alpha in human pituitary adenoma cells.

Growth factors induce cell proliferation and are implicated in the multistep process of tumorigenesis. Transforming growth factor-alpha (TGF alpha), a peptide that binds to the epidermal growth factor receptor, is expressed by carcinomas and normal tissues. To investigate the possible role of TGF alpha in adenohypophysial tumorigenesis, we studied its expression in nontumorous human pituitary and different clinically and morphologically characterized human pituitary adenomas. Ribonucleic acid was reverse transcribed and amplified by polymerase chain reaction; transcript signals were identified with marked variation in 14 of 15 adenomas, and a weak signal was detected in nontumorous pituitary. Immunohistochemical positivity was found with variable intensity in all adenoma types, but not all tumors. Ultrastructural immunogold localized TGF alpha in endoplasmic reticulum, in Golgi apparatus, and on cell membranes; surface localization was confirmed by immunofluorescence. To assess possible secretion, the reverse hemolytic plaque assay was performed; small plaques were identified using an antibody that recognizes the extracellular domain of pro-TGF alpha; however, the plaques did not increase in size with time, suggesting that they detected membrane-anchored TGF alpha. Moreover, TGF alpha was undetectable by enzyme-linked immunosorbent assay in pituitary tumor-conditioned culture media. The marked variable expression of TGF alpha, the absence of secretion in measurable quantities, and the preferential membrane localization suggest a specific juxtacrine mechanism for TGF alpha in pituitary tumorigenesis.

Adenoma↗
PubMed1995

Gonadotroph adenoma in a premenopausal woman secreting follicle-stimulating hormone and causing ovarian hyperstimulation.

The clinical manifestations of gonadotroph adenomas are almost always neurological, consequences of their large size, and are rarely endocrinological. We report an exception, a 39-yr-old woman whose gonadotroph adenoma caused supranormal serum concentrations of FSH, which resulted in the development of multiple ovarian cysts, persistent elevation of her serum estradiol concentration, and endometrial hyperplasia. She initially presented because of amenorrhea at age 30 yr and was treated for an intrasellar mass by transsphenoidal surgery at age 31 yr and again at age 36 yr. Before and after the second operation she had persistently supranormal plasma estradiol concentrations (> 1840 pmol/L) and endometrial hyperplasia. When she was evaluated at age 39 yr, transvaginal ultrasound showed multiple ovarian cysts and endometrial thickening. Her plasma estradiol level was markedly supranormal (2160 pmol/L), FSH was mildly supranormal (17.8 IU/L), and alpha-subunit was markedly supranormal (23.3 micrograms/L). Characteristic of gonadotroph adenomas, her LH beta level increased by 69% in response to TRH. Neither FSH nor alpha-subunit decreased in response to administration of the GnRH antagonist, Nal-Glu-GnRH (5 mg/12 h for 4 weeks). Excised adenoma tissue exhibited morphological features of a gonadotroph adenoma. This patient appears to be unique, in that her gonadotroph adenoma caused slightly, but persistently, supranormal concentrations of FSH, which caused ovarian stimulation, including supranormal plasma estradiol concentrations, multiple ovarian cysts, and endometrial hyperplasia. We propose that gonadotroph adenomas be considered in the differential diagnosis of patients who have this constellation of abnormalities.

Adenoma↗
PubMed1995

Heterogenous in vivo and in vitro expression of basic fibroblast growth factor by human pituitary adenomas.

Basic fibroblast growth factor (bFGF) is a potent mitogenic and angiogenic factor that is known to regulate GH, PRL, and TSH secretion. Sequences within a bFGF gene family member have been detected in transforming DNA samples derived from human PRL-secreting tumors. Furthermore, elevated serum concentrations of bFGF have been noted in patients with multiple endocrine neoplasia-1. To further examine the significance of bFGF in sporadic human pituitary adenomas, we investigated the expression of bFGF by these tumors. Using an enzyme-linked immunoassay that recognizes all 16-24 kilodalton molecular mass forms of bFGF, we measured circulating serum concentrations in 21 patients with sporadic pituitary adenomas; they ranged from less than 0.5-84 pg/mL and declined following surgical adenomectomy. To confirm the pituitary source of this growth factor, we determined in vitro bFGF release from 43 adenomas (10 GH, 7 PRL, 10 ACTH, 14 gonadotrope adenomas/oncocytomas, and 2 silent subtype 3 adenomas). bFGF was present with wide variability (0.75-2100 pg/24 h.10(5) cells) in conditioned culture media of all adenomas examined. The adenohypophysial source of this growth factor was further demonstrated by the reverse hemolytic plaque assay. Variable bFGF messenger RNA expression was identified by the reverse-transcription polymerase chain reaction technique in 9 functional (2 PRL, 5 GH, 2 ACTH) and 7 nonfunctional (1 oncocytoma, 2 null cell, 2 gonadotrope, 2 Silent Subtype 3) adenomas examined. bFGF levels were unaltered in vitro following hypothalamic hormone stimulation/inhibition. The lack of a bFGF signal peptide sequence and hypothalamic hormone-independence suggest that secretion of this factor may be independent of pituitary hormone regulation. Immunocytochemistry failed to localize bFGF in tumors that released this factor in vitro, suggesting that storage of this peptide does not correlate with its synthesis and release. In conclusion, the heterogenous expression of bFGF suggests that it may play a specific and selective role in the tumorigenic process of some pituitary adenomas.

Adenoma↗
PubMed1995

Expression of pit-1 messenger ribonucleic acid and protein in the human placenta.

It is well established that the human placenta produces a wide range of hormones similar to those secreted by the pituitary and hypothalamus. However, the physiological role and regulation of placental hormone synthesis and release are still largely unknown. GH (GH-N) is expressed in the pituitary, where it requires the tissue-specific transcription factor Pit-1. Chorionic somatomammotropin A (CS-A) and CS-B as well as the placental GH variant (GH-V), which also belong to the GH gene family and are located in the same chromosomal cluster, are expressed in the placental syncytiotrophoblast. The presence of Pit-1-binding sites in the CS-A and GH-V promoter regions predicts that Pit-1 may be expressed in the placenta. However, this has not yet been demonstrated. To examine possible similarities in the regulation of these genes in the pituitary and placenta, we studied the expression of pit-1 messenger ribonucleic acid (mRNA) in the human placenta, transformed human placental cells, and the JEG-3 choriocarcinoma cell line. Polymerase chain reaction (PCR) products of the expected size were amplified from first and third trimester placentas, transformed placental cells, and JEG-3 complementary DNA by reverse transcription-PCR. The pit-1-specific sequence was confirmed by restriction endonuclease digestion, Southern hybridization, and DNA sequencing. Human pituitary tissue was used as a positive control; no PCR product was obtained from hippocampus (negative control). In situ hybridization of placental tissue sections revealed the presence of pit-1 mRNA in first and third trimester syncytiotrophoblast. Pit-1 protein was localized by immunohistochemistry with the same tissue distribution and a nuclear localization pattern. These data demonstrate expression of pit-1 mRNA and Pit-1 protein in the human placenta, thus questioning its role as a pituitary-specific regulator of GH-N gene transcription. The expression of Pit-1 in the placenta, together with its previously demonstrated capability to bind to and activate the CS-A and the GH-V promoters, suggests that it may play a role in the regulation of hormones belonging to the GH gene family in both pituitary and placenta.

Base Sequence↗
PubMed1995

Clinical case seminar: lymphocytic hypophysitis: clinicopathological findings.

This report describes the clinicopathological features of 16 patients with lymphocytic hypophysitis and compares the results with the published literature. There were 2 males and 14 females in this series. In 10 of the 14 females (71%), the presentation was associated with pregnancy. Nine patients (56%) presented with symptoms of an expanding pituitary sellar mass, 10 (63%) had anterior pituitary hypofunction, 3 had diabetes insipidus (19%). Progressive undiagnosed hypopituitarism led to the demise of 3 patients (19%). Hyperprolactinemia was encountered in 6 patients (38%), and elevated growth hormone levels (GH) resulted in IGF-1 excess in one patient. Computed tomography (CT) and magnetic resonance (MR) imaging revealed features of a pituitary mass mimicking an adenoma in 10 cases (83%). Four patients (25%) had associated autoimmune thyroiditis. Morphologic examination of the pituitary and immunohistochemistry showed a polyclonal lymphoplasmacytic infiltrate as well as occasional neutrophils, eosinophils, and macrophages; the chronic inflammatory process resulted in focal or diffuse adenohypophysial destruction of variable severity with associated fibrosis. The inflammatory infiltrate involved the neurohypophysis in 2 cases and one of these patients had diabetes insipidus; the posterior lobe of two other patients with diabetes insipidus was not examined morphologically. We conclude that lymphocytic hypophysitis should be considered in the differential diagnosis of females with pituitary enlargement presenting in the peripartum period as well as those patients in whom pituitary hormone deficiency and/or excess is noted in association with a co-existing autoimmune disorder. This clinical suspicion should probably also be extended to include patients presenting with rapidly growing pituitary masses associated with compressive symptoms with or without pituitary hormone dysfunction. Because of the transient endocrine and compressive features of this condition in many instances, conservative treatment on the basis of clinical suspicion alone may obviate the need for aggressive pituitary surgery.

Adult↗
PubMed1995

Papillary Hürthle cell carcinoma with lymphocytic stroma. "Warthin-like tumor" of the thyroid.

We report 13 cases of a peculiar thyroid tumor of follicular epithelial differentiation with distinctly papillary architecture, oxyphilic cytology, and lymphocytic infiltrates in papillary stalks. The majority of these tumors arose in glands with chronic lymphocytic thyroiditis. The combination of oxyphilic cells and lymphocytic stroma gives these tumors a startling resemblance to papillary cystadenoma lymphomatosum, or "Warthin's tumor" of the salivary gland. Twelve tumors occurred in women (age range: 26-66 years, mean 44 years). Two tumors were in the isthmus, six in the right lobe, and four in the left lobe. The only man, 34 years old, had multiple bilateral tumor nodules. The lesions ranged from 0.3 cm to 3.5 cm in maximum dimension. The largest lesion, in a 58-year-old woman, infiltrated skeletal muscle. Three other patients had lymph node metastases, while the nine remaining tumors were confined to the thyroid. Follow-up in these cases suggests that although the histological appearance of these neoplasms is unusual, they behave as typical papillary carcinomas. The striking lymphocytic infiltration and oxyphilic metaplasia in these tumors as well as the association with chronic lymphocytic thyroiditis suggest that as yet undefined immunological mechanisms may play a role in the pathogenesis of this disorder.

Adenocarcinoma, Papillary↗
PubMed1995

Brief report: detection of high-molecular-weight cytokeratins in neoplastic and non-neoplastic thyroid tumors using microwave antigen retrieval.

Previous studies have demonstrated the utility of immunohistochemical staining for high-molecular-weight cytokeratins in the distinction of papillary carcinoma from other neoplasms of the thyroid, however, this technique was reliable only when applied to frozen tissues. Our objective in this study was to evaluate the use of this antibody in diagnostic thyroid pathology using paraffin-embedded materials with microwave antigen retrieval. We studied 89 thyroid tumors including 45 papillary carcinomas, 28 nodular hyperplasias, 10 follicular adenomas, and 6 follicular carcinomas. Moderate-to-strong diffuse staining was confined to papillary carcinoma, whereas follicular neoplasms and hyperplastic nodules were either negative or showed focal staining. These results confirm the utility of high-molecular-weight cytokeratins immunostaining in diagnostic thyroid pathology, and obviate the need for frozen material to apply this method. As paraffin-embedded tissues are more readily available, we recommend the use of high-molecular-weight cytokeratins with microwave antigen retrieval in cases in which it is difficult to distinguish papillary carcinoma from other thyroid tumors.

Antigens↗
PubMed1994

Cerebral and cerebellar gangliocytomas: a morphological study of nine cases.

Hypothalamic gangliocytomas have been shown to contain immunoreactivity for hypophysiotropic peptides and some have been associated with endocrine dysfunction. Extrahypothalamic gangliocytomas are usually not associated with endocrine abnormalities. We studied nine cerebral or cerebellar gangliocytomas from six men and three women; none of the patients had detectable alterations of endocrine homeostasis. On histological examination, the tumor cells resembled hypothalamic neurons. Electron microscopy disclosed the presence of dense-core vesicles in neuronal cytoplasm and processes resembling Herring bodies, and there were synaptic contacts between tumor cells. All but two tumors contained immunocytochemical positivity for at least one peptide hormone or amine; these included somatostatin, corticotropin-releasing hormone, beta-endorphin, galanin, vasoactive intestinal peptide, calcitonin, serotonin, catecholamines or met-enkephalin. These tumors have been thought to represent neoplasms arising in ectopic autonomic neural tissue. Their morphological features, their similarity to hypothalamic gangliocytomas and the multiple immunoreactivities shown here suggest that they can be regarded as tumors of peptidergic neurons that are widely distributed throughout the central nervous system.

Adolescent↗
PubMed1994

Intrathyroidal lymphoepithelial cysts of probable branchial origin.

Lymphoepithelial cysts with histological features characteristic of branchial cleft cysts have been reported to occur rarely in the thyroid gland. To our knowledge only six cases of this lesion have been reported. Since these reports brought this entity to our attention, we have noted that intrathyroidal lymphoepithelial cysts are not rare lesions. We report six further cases; four were incidental histological findings, and two lesions were clinically detected masses. Each of the cysts had a squamous epithelial lining with abundant underlying lymphoid tissue, including lymphoid aggregates with large reactive germinal centers. All cases were associated with chronic lymphocytic thyroiditis. Because of the histological resemblance to branchial cleft cysts, it is postulated that these lymphoepithelial cysts are branchial in origin. The histogenesis of branchial cleft cysts is unknown; however, the ultimobranchial body, originating from branchial pouches four and/or five, contributes to the embryological development of the thyroid. Branchial cleft derivatives, such as thymus and parathyroid, develop in close association with the thyroid and may be found within the thyroid gland. These branchial cleft-like cysts also may arise from branchial cleft derivatives, and their enlargement may be related to the immunological mechanisms associated with autoimmune thyroiditis.

Adult↗