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PubMed2005

Iodine 123 metaiodobenzylguanidine radio-guided navigation surgery for recurrent medullary thyroid carcinoma in a girl with multiple endocrine neoplasia type 2B.

Multiple endocrine neoplasia type 2B (MEN 2B) is an inherited cancerous syndrome characterized by medullary thyroid carcinoma (MTC), adrenal pheochromocytoma, marfanoid habitus, and enteric ganglioneuromatosis. In this syndrome, a high frequency of persistent elevation of the serum calcitonin level, a sensitive marker for MTC, after total thyroidectomy has been reported, and the prognosis of such patients depends upon complete resection of recurrent MTC by repeated surgery. The authors performed iodine 123 metaiodobenzylguanidine ((123)I-MIBG) radio-guided navigation surgery for recurrent MTC in a 14-year-old girl with MEN 2B. She had undergone 4 neck operations, including total thyroidectomy at the age of 7 years. An intravenous injection of 100 MBq (123)I-MIBG was followed by the fifth surgery. At surgery, the cervical and upper mediastinal areas were filled with adhesional scar tissue, in which a gamma-scintillation probe conducted hot spots of isotope uptake by cancerous cells. Histopathology of resected specimens showed scattered nests of MTC cells corresponding to gamma-scintillation counts. Intraoperative (123)I-MIBG scanning is of substantial benefit for children with MEN 2B undergoing surgery for recurrent MTC.

3-Iodobenzylguanidine↗

PubMed1994

Parent-of-origin effects in multiple endocrine neoplasia type 2B.

Multiple endocrine neoplasia type 2B (MEN 2B) is characterized by medullary thyroid carcinoma, pheochromocytomas, mucosal neuromas, ganglioneuromas, and skeletal and ophthalmic abnormalities. It is observed as both inherited and sporadic disease, with an estimated 50% of cases arising de novo. A single point mutation in the catalytic core region of the receptor tyrosine kinase, RET, has been observed in germ-line DNA of MEN 2B patients. We have analyzed 25 cases of de novo disease in order to determine the parental origin of the mutated RET allele. In all cases the new mutation was of paternal origin. We observe a distortion of the sex ratio in both de novo MEN 2B patients and the affected offspring of MEN 2B transmitting males. These results suggests a differential susceptibility of RET to mutation in paternally and maternally derived DNA and a possible role for imprinting of RET during development.

Chromosomes, Human, Pair 10↗

PubMed1995

No mutation at codon 918 of the RET gene in a family with multiple endocrine neoplasia type 2B.

Multiple endocrine neoplasia type 2B (MEN 2B) is a rare cancer syndrome which is inherited in an autosomal dominant manner. The molecular basis of this condition has recently been defined as a mutation of codon 918 of exon 16 of the RET proto-oncogene. The mutation in codon 918 has been described in 69 out of 72 families with MEN 2B. We have studied a brother and sister who undoubtedly have the features of MEN 2B as evidenced by medullary thyroid carcinoma, phaeochromocytoma, mucosal neuromas and skeletal abnormalities. Neither of these patients has the classic gene mutation at codon 918 of exon 16 of the RET proto-oncogene, and although exons 2-20 have also been sequenced, no abnormality has been found. DNA analysis is a sensitive method of screening families for the MEN 2 syndromes. The absence of the mutation at codon 918 in a phenotypically normal individual would refute the diagnosis of MEN 2B, but in an individual with some of the features of MEN 2B would make the clinician reconsider the diagnosis. This family demonstrates that, although it is rare, the absence of the mutation in codon 918 of exon 16 of the RET proto-oncogene does not always exclude the diagnosis of MEN 2B. In such families routine biochemical screening for medullary thyroid carcinoma and phaeochromocytoma must be maintained for all individuals at genetic risk.

Adolescent↗

PubMed1994

Single missense mutation in the tyrosine kinase catalytic domain of the RET protooncogene is associated with multiple endocrine neoplasia type 2B.

Multiple endocrine neoplasia type 2B (MEN 2B) is a human cancer syndrome characterized by medullary thyroid carcinoma (MTC), pheochromocytomas, mucosal neuromas, ganglioneuromas of the intestinal tract, and skeletal and ophthalmic abnormalities. It appears both as an inherited disorder and as de novo disease. Sequence analysis of germ-line DNA from MEN 2B patients revealed the existence of the same point mutation in the RET protooncogene in 34 unrelated individuals. This sequence difference was not observed in 93 unaffected individuals, including the normal parents of 14 de novo MEN 2B patients. The mutation (ATG-->ACG) results in the replacement of methionine with threonine within the catalytic core region of the tyrosine kinase domain. We propose that this amino acid replacement effects substrate interactions and results in dominant oncogenic activity by the RET protein. Missense mutations in the extracellular ligand-binding domain of the RET protooncogene previously have been associated with two other disorders [MEN 2A and familial MTC (FMTC)] in which MTC is observed. MEN 2B represents the third form of heritable MTC known to be an allele of RET. Alterations in two different functional domains of the putative receptor protein tyrosine kinase are implicated in development of MTC.

Alleles↗

PubMed1979

C-cell disease of the thyroid gland in multiple endocrine neoplasia, type 2b.

Multiple endocrine neoplasia, type 2b (MEN 2b) is a disorder characterized by C-cell disease of the thyroid gland (medullary carcinoma or C-cell hyperplasia, or both), pheochromocytoma, ganglioneuromatosis, and skeletal and connective tissue abnormalities. The medullary thyroid carcinoma (MTC) is bilateral and multicentric; it metastasizes locally and distally, often before the disease is recognized. Histologically proven C-cell disease was present in 89 of the 107 patients (83%) reported with the condition, including 17 Mayo Clinic patients (average age at diagnosis, 19.2 years). Nineteen of the 107 patients (18%) died of MTC (average age at death, 25.3 years); 9 (8%) succumbed to pheochromocytoma, 7 of these also having metastatic MTC; 13 12%) died of other or unknown causes, but 2 of these had disseminated MTC as well; 29 (27%) survive with metastatic MTC; an additional 21 (20%) are alive, but concentrations of plasma immunoreactive calcitonin (iCT) have not been measured; 6 more (6%), 5 of whom had thyroidectomy before the age of 12 years, are alive with normal plasma concentrations of iCT; and the remaining 10 (9%) have been lost to follow-up. Survival of patients with MEN 2b after operation was reduced when compared with that of a control population -- 80% versus 99% at 5 years and 50% versus 98% at 10 years. The only effective treatment for MTC is total thyroidectomy before metastasis occurs. "Cure" of MTC in patients with MEN 2b has generally been obtained in those having total thyroidectomy before age 12. Therefore, in young patients suspected of having MEN 2b, we recommend prompt evaluation of C-cell function by measurement of stimulated concentrations of iCT and treatment by total thyroidectomy if results are abnormal.

Adolescent↗

PubMed1978

Multiple endocrine neoplasia, type 2b.

Multiple endocrine neoplasia, type 2b, is a disorder of unknown etiology with major involvement of the thyroid and adrenal glands, the autonomic nervous system, and connective tissue. It is transmissible with an autosomal dominant pattern of inheritance, but since most cases are not familial, they presumably represent mutations. The thyroid gland exhibits bilateral medullary carcinoma, which is a metastasizing lethal neoplasm in the syndrome requiring total thyroidectomy once abnormal basal or stimulated concentrations of plasma immunoreactive calcitonin have been demonstrated. The adrenal medullary tumors--pheochromocytomas--although rarely malignant, are potentially lethal because of their cardiovascular effects. Since the adrenal involvement is usually bilateral, total bilateral adrenalectomy with excision of any extraadrenal paraganglioma is the surgical treatment. Parathyroid hyperplasia occurs rarely in the syndrome. Treatment of it should be conservative, that is, limited to excision of enlarged parathyroid glands. Major portions of the autonomic nervous system, both sympathetic and parasympathetic, nerves and ganglia, exhibit hypertrophy, hyperplasia, and disorder of structure--a group of changes designated ganglioneuromatosis. This may be largely responsible for the striking eye and oral findings--the hallmarks of the syndrome--and also for some of the serious symptoms and complications of the syndrome, particularly those referable to the alimentary tract. Ganglioneuromatosis is also found in the salivary glands, pancreas, gallbladder, upper respiratory tract, and urinary bladder. The connective tissue abnormality is manifested by increased growth of long bones, ribs, and skull, resulting in a marfanoid habitus, and also by skeletal and joint abnormalities together with increased laxity of ligaments. Ninety cases of MEN 2b have been reported, and although follow-up information is incomplete, 27 patients (30 percent) are known to be dead because of the syndrome. The causes of death have been medullary thyroid carcinoma (15 deaths), pheochromocytoma (10 deaths), and alimentary tract complications (2 deaths). An additional 21 patients (22 percent) are known to have metastatic MTC. We are aware of only 2 patients who, 5 years after thyroidectomy, have apparently been cured of MTC, but both are still at risk for adrenal medullary disease. MEN 2b is, therefore, a very serious disorder that requires urgent treatment of the endocrine tumors. Fortunately, the majority of patients with the syndrome are easily recognized because of an abnormal phenotype typified by thick, bumpy lips and a marfanoid habitus. Since these findings signal high risk for the potentially lethal endocrine neoplasms, patients having the characteristic appearance need evaluation of thyroidal C-cell and adrenal medullary function.

Adrenal Gland Neoplasms↗

PubMed1981

Ocular histopathology in multiple endocrine neoplasia type 2b.

Multiple endocrine neoplasia type 2b is a syndrome, often familial, characterized by medullary carcinoma of the thyroid gland, pheochromocytoma, and many mucosal neuromas in patients who frequently have a marfanoid habitus. The ophthalmic findings are distinctive and include conjunctival and eyelid neuromas, keratoconjunctivitis sicca, and, most characteristically, greatly thickened corneal nerves. Ocular histopathologic study of a 30-year-old man demonstrated thickened nerves in the ciliary body, iris, and corneoscleral limbal regions. In these regions, the nerves were a mixture of myelinated and unmyelinated fibers. Sections through the thickened corneal nerves, 1.5 mm centrally from the corneoscleral limbus, showed only nonmyelinated nerves associated with Schwann cells. The many axons were normal in appearance but varied in diameter; some were between 0.1 and 0.2 ng and others between 1.0 and 1.4 ng. An unexpected finding was numerous ganglion cells in the ciliary body. The subconjunctival tissue showed neuromas with a minimum of fibrous structure. Sections of the lacrimal gland showed normal glandular tissue.

Adult↗

PubMed1976

Mucosal ganglioneuromatosis, medullary thyroid carcinoma, and pheochromocytoma: multiple endocrine neoplasia, type 2b.

Multiple endocrine neoplasia, type 2b, is a designation that has been proposed for the combination of medullary thyroid carcinoma, pheochromocytoma, mucosal neuromas, and somatic abnormalities. The neural lesions produce a characteristic diffuse or nodular enlargement of lips, tongue, and buccal mucosa. Microscopically, the lesions are composed of unencapsulated masses of hypertrophied and elongated nerves in which are found rare ganglion cells. The histologic similarity between the oral mucosal lesions and the alimentary tract ganglioneuromatosis in the syndrome suggests that the term ganglioneuromatosis is the most appropriate designation for the oral lesions. The oral lesions signal high risk for two potentially lethal neoplasms--medullary thyroid carcinoma and pheochromocytoma. Thus, patients having the characteristic findings are in urgent need of repeated evaluation of thyroidal C-cell and adrenal medullary function.

Adolescent↗

PubMed1992

Genetics of the multiple endocrine neoplasia type 2B syndrome.

Multiple endocrine neoplasia type 2B (MEN 2B) is similar to MEN 2A in that both autosomal dominant syndromes include medullary thyroid cancers and pheochromocytomas. It is distinct in that MEN 2B patients have much earlier age of onset with more aggressive tumors and mucosal neuromas of the lips and tongue. The neuromas allow ascertainment generally before age 5. Studies of two and three generations of 14 MEN 2B families disclosed close linkage of the MEN 2B gene to DNA markers to which MEN2A had been linked. Multipoint analysis utilizing additional results in three generations of a 15th family have disclosed a peak total lod score of 8.89 at the midpoint between the centromere markers D10Z1 and RBP3 on the long arm (band q11). One recombinant was observed between D10Z1 and MEN2B, but this individual was not recombinant with D10S94. These studies suggest physical proximity of MEN2A and MEN2B but do not establish allelism for the gene(s).

Adult↗

PubMed2000

C-cell hyperplasia, pheochromocytoma and sympathoadrenal malformation in a mouse model of multiple endocrine neoplasia type 2B.

Dominantly inherited multiple endocrine neoplasia type 2B (MEN2B) is characterized by tumors of the thyroid C-cells and adrenal chromaffin cells, together with ganglioneuromas of the gastrointestinal tract and other developmental abnormalities. Most cases are caused by substitution of threonine for Met918 in the RET receptor tyrosine kinase, which is believed to convert the RET gene to an oncogene by altering the enzyme's substrate specificity. We report the production of a mouse model of MEN2B by introduction of the corresponding mutation into the ret gene. Mutant mice displayed C-cell hyperplasia and chromaffin cell hyperplasia progressing to pheochromocytoma. Homozygotes did not develop gastrointestinal ganglioneuromas, but displayed ganglioneuromas of the adrenal medulla, enlargement of the associated sympathetic ganglia and a male reproductive defect. Surprisingly, homozygotes did not display any developmental defects attributable to a loss-of-function mutation. Thus, while our results support the conclusion that the Met918Thr substitution is responsible for MEN2B, they suggest that the substrate specificity of the RET kinase does not interfere with its normal role in the development of the kidneys and enteric nervous system.

Adrenal Gland Neoplasms↗

PubMed2001

Typical ocular findings in a patient with multiple endocrine neoplasia type 2b syndrome.

BACKGROUND: Multiple endocrine neoplasia (MEN) type 2b syndrome is accompanied by typical ocular findings; however, the disease is often only diagnosed at an advanced stage by symptoms of C-cell carcinoma or pheochromocytoma and is then fatal in most cases. Therefore, the importance of ophthalmic assessment in making the diagnosis has to be stressed. METHODS: The history and ocular findings of a patient with MEN 2b syndrome are described, and a brief overview of the syndrome is given. RESULTS: Slit-lamp examination showed extremely thickened corneal nerves as well as multiple small plexiform and nodular subconjunctival tumors. Both eyes also displayed thickened upper and lower eyelids. A molecular genetic study of the RET proto-oncogene showed a heterozygous ATG to ACG mutation in codon 918 of exon 16. CONCLUSION: Greatly thickened corneal nerves and subconjunctival tumors may be the first hint of MEN 2b. Whenever greatly thickened corneal nerves are detected, MEN 2b must be ruled out.

Adrenal Gland Neoplasms↗

PubMed1999

Colonic manifestations of multiple endocrine neoplasia type 2B: report of four cases.

Multiple endocrine neoplasia type 2B is best known for its endocrine manifestations and typical phenotype. The gastrointestinal manifestations, however, are also an important and commonly unrecognized component of the syndrome. We present four cases that demonstrate the varied presentation of patients with colonic manifestations of multiple endocrine neoplasia type 2B. We discuss the cause, diagnostic significance, and management of the colonic disease that is a component of multiple endocrine neoplasia type 2B.

Adolescent↗

PubMed1997

A case of multiple endocrine neoplasia type 2B.

A sporadic case of multiple endocrine neoplasia type 2B in a twenty-six year old man who manifested medullary thyroid carcinoma, multiple mucosal neuromas of the tongue and a marfanoid habitus is reported. At the time of diagnosis, he also had multiple liver and lung metastases. Genetic analysis of his lymphocytes revealed a point mutation in exon 16 of the RET proto-oncogene. Since multiple endocrine neoplasia type 2B has a relatively poor prognosis because of the occasional aggressive behavior of medullary thyroid carcinoma, the necessity of the genetic diagnosis of multiple endocrine neoplasia in the early stage is suggested.

Adult↗

PubMed1998

Absence of rectoanal inhibitory reflex in a child with multiple endocrine neoplasia type 2B.

BACKGROUND: Patients with multiple endocrine neoplasia (MEN) type 2B inherently present with gastrointestinal motility disorders as well as medullary thyroid carcinoma, adrenal pheochromocytoma, and Marfanoid habitus. METHODS: The authors examined gut motility function in a 7-year-old girl with MEN type 2B who had suffered from chronic constipation and recurrent acalculous cholecystitis since infancy. RESULTS: Results of total gastrointestinal barium meal and enema studies showed marked hypoperistalsis of the gut and entire colonic dilatation. Histopathologic study results of the gut wall from the stomach, duodenum, and rectum showed hyperplasia of the submucosal and intramuscular neural plexuses in all specimens. Anorectal manometry demonstrated disarrangement of the internal sphincter rhythmic wave and a complete absence of the rectoanal inhibitory reflex. CONCLUSION: These data suggest that gut motility disorders in MEN type 2B are caused by inadequately organized autonomic nervous system activity that originates from hyperplasia of the enteric nervous system.

Adrenal Gland Neoplasms↗

PubMed2000

A two-hit model for development of multiple endocrine neoplasia type 2B by RET mutations.

Multiple endocrine neoplasia (MEN) type 2B mutations have been reported at methionine 918 or alanine 883 in the tyrosine kinase domain of the RET proto-oncogene. Recently, a new combination of two germline missense mutations at valine 804 and tyrosine 806 was identified in a patient with MEN 2B-like clinical phenotypes including medullary thyroid carcinoma, mucosal neuroma, and marfanoid habitus. In this case, valine 804 and tyrosine 806 were replaced with methionine and cysteine, respectively. In the present study, biological activities of RET with these new mutations were compared with those with known MEN 2A or MEN 2B mutations. The transforming activity of RET with the V804M/Y806C mutation was about 8- to 13-fold higher than that of RET with a single V804M or Y806C mutation. Like RET with the M918T or A883F MEN 2B mutation, the transforming activity of RET with the V804M/Y806C mutation was not affected by substitution of phenylalanine for tyrosine 905 that abolished the activity of RET with the MEN 2A mutation. On the other hand, substitution of phenylalanine for tyrosines 864 and 952 drastically diminished the activity of RET with the V804M/Y806C, M918T or A883F mutation, suggesting that these three mutant proteins have similar biological properties.

3T3 Cells↗

PubMed2004

Multiple endocrine neoplasia type 2B in a Chinese patient.

Multiple endocrine neoplasia type 2B syndrome is rarely reported in Chinese patients. A 25-year-old Chinese male presented with full-blown clinical features of this syndrome, including bilateral phaeochromocytomas, medullary thyroid carcinoma, and characteristic phenotypic features. One-stage surgical treatment was performed and subsequent genetic analysis confirmed a point mutation at codon 918 in exon 16 of the RET proto-oncogene. The mutation was arising de novo as there was no corresponding mutation found in both his parents or younger sister. Data published to date suggest there is no difference in the genetic and pathophysiologic basis, nor clinical characteristics of multiple endocrine neoplasia type 2B in Chinese patients. As the disease can be lethal, early diagnosis by prompt recognition of the characteristic phenotypic features followed by surgical treatment should improve the outcome. Family screening is essential to identify at-risk family members for prophylactic treatment.

Adrenalectomy↗

PubMed1995

Germ line mutation in the RET proto-oncogene associated with familial multiple endocrine neoplasia type 2B: a case report.

Multiple endocrine neoplasia type 2 (MEN 2) is a dominantly inherited cancer syndrome. MEN 2B is characterized by the combined occurrence of medullary thyroid carcinoma (MTC), pheochromocytoma, mucosal neuroma and Marfanoid habitus. Recently, a missense mutation in codon 918 of the proto-RET has been reported in the germ line of apparently distinct families with MEN 2B. In the present paper we first show a familial case of MEN 2B in Japan also to be associated with a germ line mutation in codon 918 of the proto-RET. The mutation was the substitution of a threonine for a methionine in the tyrosine kinase domain of the protein. The germ-like mutations of the proto-RET in MEN 2A and MEN 2B are the first examples of a dominantly acting oncogenic point mutation initiating human hereditary neoplasia.

Adrenal Gland Neoplasms↗

PubMed1998

Presence of the 918 mutation in the RET proto-oncogene in a Mexican patient with multiple endocrine neoplasia type 2B.

The dominantly inherited Multiple Endocrine Neoplasia cancer syndrome type 2B (MEN2B) is characterized by the presence of medullary thyroid carcinoma (MTC), phaechromocytoma (PHAEO), mucosal neuromas, ganglioneuromas of the intestinal tract, skeletal and ophthalmic abnormalities. MEN2B has been associated with a specific point mutation in the tyrosine kinase domain of the RET proto-oncogene (918RET mutation). We investigated a Mexican patient MEN2B for the presence of the 918RET mutation using the polymerase chain reaction followed by restriction endonuclease digestion. We have detected this mutation in DNA from the patient's MTC, PHAEO, and peripheral blood cells, but not in DNA from the patient's mother, suggesting that this mutation arose de novo. Our results are in agreement with the suggestion that the 918RET mutation is present in a vast majority of MEN2B cases around the world.

Adult↗