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PubMed2000

Tissue-specific carcinogenesis in transgenic mice expressing the RET proto-oncogene with a multiple endocrine neoplasia type 2A mutation.

Germ line mutations of the RET proto-oncogene are responsible for the development of multiple endocrine neoplasia type 2A (MEN 2A), an inherited cancer syndrome characterized by medullary thyroid carcinoma, pheochromocytoma, and parathyroid hyperplasia. To study the mechanism of tissue-specific tumor development by RET with a MEN2A (cysteine 634-->arginine) mutation, we generated transgenic mice by introducing the RET-MEN2A gene fused to Moloney murine leukemia virus long terminal repeat. Expression of the transgene and its product was detected at variable levels in a variety of tissues including thyroid, heart, liver, colon, parotid gland, and brain. All of 29 mice analyzed developed thyroid C-cell hyperplasia or medullary carcinoma, accompanying high levels of serum calcitonin. In addition, development of mammary or parotid gland adenocarcinoma was observed in one-half of the transgenic mice. RET dimerization and its complex formation with Shc and Grb2 adaptor proteins were detected in tumor tissues. Unexpectedly, no tumor formation was found in other tissues despite RET-MEN2A expression where RET dimerization was undetectable. Because these tissues but not tumors expressed glial cell line-derived neurotrophic factor family receptor alpha (GFR alpha) at high levels, this suggested that GFR alpha expression may interfere in the dimerization of the RET-MEN2A mutant proteins, leading to tissue-specific tumor development in vivo.

3T3 Cells↗

PubMed2006

Cellular effects of imatinib on medullary thyroid cancer cells harboring multiple endocrine neoplasia Type 2A and 2B associated RET mutations.

BACKGROUND: Activating mutations in the RET gene, which encodes a tyrosine kinase receptor, often cause medullary thyroid carcinoma (MTC). Surgical resection is the only curative treatment; no effective systemic treatment is available. We evaluated imatinib, a tyrosine kinase inhibitor currently used to treat chronic myelogenous leukemia and gastrointestinal stromal tumors, as a potential drug for systemic treatment of MTC, in 2 MTC-derived cell lines expressing multiple endocrine neoplasia-associated mutant RET receptors. METHODS: We determined RET expression and Y1062 phosphorylation using Western blot analysis and quantitative polymerase chain reaction. We determined the effects on cell proliferation by a 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide assay, and we used fluorescence-activated cell sorter analysis with annexin V/propidium iodide staining to study imatinib-induced cell-cycle arrest, apoptosis, and cell death. RESULTS: Imatinib inhibited RET Y1062 phosphorylation in a dose-dependent manner after 1.5 hours of exposure. After 16 hours both RET Y1062 phosphorylation and protein expression levels were affected. Dose-dependent decreases in cell proliferation of both cell lines after exposure to imatinib with inhibitory concentration of 50% levels of 23 +/- 2 micromol/L and 25 +/- 4 micromol/L were seen. These values are high, compared with those for chronic myelogenous leukemia and gastrointestinal stromal tumors. We further could show that imatinib induced cell-cycle arrest, and apoptotic and nonapoptotic cell death. CONCLUSIONS: Imatinib inhibits RET-mediated MTC cell growth affecting RET protein levels in vitro in a dose-dependent manner. The concentration of imatinib necessary to inhibit RET in vitro, however, makes it impossible to conclude that imatinib monotherapy will be a good option for systemic therapy of MTC.

Apoptosis↗

PubMed1991

Incidence of prominent corneal nerves in multiple endocrine neoplasia type 2A.

We studied the increased visibility of corneal nerves inside an 8-mm diameter central corneal area in 14 patients with multiple endocrine neoplasia type 2A, one patient with multiple endocrine neoplasia type 2B, five patients with nonhereditary medullary thyroid carcinoma, ten patients with anterior keratoconus, and ten normal subjects. We used a grading system (grade 0 through grade 4) for nerve visibility based on slit-lamp biomicroscopic examination and photographic documentation. All 20 normal eyes showed either grade 0 or grade 1, which indicated no pathologic thickening of corneal nerves. Sixteen of the 28 eyes (57%) with multiple endocrine neoplasia type 2A, however, were evaluated as grade 2 or higher, which indicated thickened corneal nerves. The incidence of high nerve visibility in eyes with multiple endocrine neoplasia type 2A was significantly greater compared to normal eyes (P less than .0001), anterior keratoconus (P less than .0001), and nonhereditary medullary thyroid carcinoma (P = .0012). Furthermore, eight of the 28 eyes (29%) with multiple endocrine neoplasia type 2A showed markedly prominent corneal nerves (grade 3 and 4), a prominence similar to those seen in eyes with multiple endocrine neoplasia type 2B. There was no definite relationship among prominent nerve, age of the patient, and occurrence of pheochromocytoma. These findings suggest that over half of all patients with multiple endocrine neoplasia type 2A show corneal nerves pathologically thickened to different degrees.

Adult↗

PubMed1995

Primary hyperparathyroidism in multiple endocrine neoplasia type 2A.

The rarity of primary hyperparathyroidism (PHPT) in multiple endocrine neoplasia type 2A (MEN 2A) led us to study clinical findings, surgical therapy and outcome in 67 patients in order to evaluate our therapeutic strategy. The retrospective study was based on cases registered by the EUROMEN study group (nine participating centres) from 1972 to 1993. Characteristics of PHPT in 67 patients (41 females, 26 males) with MEN 2A were reviewed. All patients underwent exploratory neck surgery; PHPT was confirmed histologically and/or biochemically. The median age at diagnosis of PHPT was 38 years. In 75% of the patients, PHPT and medullary thyroid carcinoma were diagnosed synchronously, while in 4%. PHT was diagnosed earlier. In 18% of the patients, PHPT was diagnosed after thyroidectomy, and in 3%, after discovery of pheochromocytoma. Primary hyperparathyroidism was asymptomatic in 84% of the patients; 15% suffered from renal stones. Serum calcium was slightly elevated in 69% (2.9 +/- 0.2 mmol-1) and normal in 16% of subjects. A single adenomectomy was performed in 42% of the patients, subtotal parathyroidectomy in 31% and total parathyroidectomy with autotransplantation in 16%. Independent from the extent of resection, cure was achieved in 94% of the patients, including 13% with hypoparathyroidism; hypercalcaemia persisted in 3% and no information was available in 3%. In an 8-year follow-up, hypercalcaemia recurred in 12% of the patients, although half had undergone parathyroidectomy totally or subtotally. CONCLUSION. MEN 2A-related PHPT is characterized by a mild hypercalcemia which is mostly asymptomatic and can be cured by simple resection of an enlarged parathyroid gland in most cases.

Adolescent↗

PubMed1996

Medullary thyroid carcinoma in children with multiple endocrine neoplasia types 2A and 2B.

Recently it has become possible to identify persons who have multiple endocrine neoplasia (MEN) syndrome types 2A and 2B based on the presence of missense mutations in the RET protooncogene. Kindred members who have inherited these syndromes can be identified before clinical or biochemical evidence of medullary thyroid carcinoma (MTC) develops, the malignancy that occurs in all affected patients. It is not known whether prophylactic removal of the thyroid gland early in childhood, based on a positive genetic test result, has a better clinical outcome than that associated with thyroidectomy after MTC is diagnosed clinically or biochemically. The authors' goal was to determine the long-term outcome for patients with MEN 2A and 2B who had thyroidectomy for MTC during childhood. These results were compared with those of patients who had prophylactic removal of the thyroid gland after the genetic diagnosis of MEN 2A was established. The hospital records of 49 children with MEN 2A or 2B were reviewed. Each patient had thyroidectomy for MTC before 16 years of age. The mean age at the time of operation was 10 years, and the mean follow-up period for those who had surgery before the availability of direct DNA genetic testing was 9.8 years. The indications for surgery included an elevated basal or stimulated plasma calcitonin level, a positive genetic test result, a thyroid mass, family history of MTC, or a phenotype diagnostic of MEN 2B. All children for whom the diagnosis of MEN 2A was established by direct genetic testing had thyroidectomy within the last 2 years. Of the 11 patients with MEN 2B who underwent thyroidectomy during childhood, 10 had MTC, and only 3 (27%) remain free of disease after the mean follow-up period of 11 years. One patient died, and seven are alive with persistent MTC. Among the 24 patients with MEN 2A who had their thyroid glands removed because of a family history of MTC or because of biochemical evidence of the disease, 5 (21%) have persistent or recurrent MTC after the mean follow-up period of 9.3 years. In four of these, the MTC was confined to the thyroid gland at the time of thyroidectomy. Of the 14 children who had thyroidectomy based on direct DNA testing, MTC was present in 11. Only four had elevated levels of stimulated plasma calcitonin before surgery. None had lymph node metastasis or surgical complications. The authors conclude that a significant number of patients with MEN 2A or 2B who undergo thyroidectomy in childhood for MTC have persistent or recurrent disease long-term. The genetic diagnosis of patients with these syndromes may allow for prophylactic surgery before the development of biochemical or clinical evidence of MTC. This approach is safe, but longer clinical follow-up will be necessary to confirm that MTC has been cured.

Adolescent↗

PubMed1995

Medullary thyroid carcinoma: recent advances and management update.

Medullary thyroid carcinoma (MTC) is a malignancy of the thyroid C-cells that comprises 5-10% of all thyroid cancers. MTC occurs in both sporadic and familial forms, the latter making up 25% of all MTCs and being comprised of three distinct syndromes--multiple endocrine neoplasia type 2A (MEN 2A), multiple endocrine neoplasia type 2B (MEN 2B), and familial medullary thyroid carcinoma (FMTC). To date, screening for MTC has been performed using the pentagastrin stimulation test, which is a provocative test for calcitonin release. Germline mutations in the RET protooncogene have been identified in families manifesting these syndromes and genetic screening of individuals at risk of one of these syndromes has become integral to their clinical management. The majority of the mutations associated with MEN 2A and FMTC are tightly clustered in a cysteine-rich region of the RET receptor. A single mutation associated with MEN 2B is in the the tyrosine kinase domain of the RET receptor. Somatic mutations have been identified in the tumor tissue of individuals with sporadic MTC and may prove to be helpful markers in discerning the hereditary or sporadic nature of the MTC. There is general agreement that the primary operation for MTC should include total thyroidectomy and central neck lymph node clearance. The role of microdissection for recurrent disease awaits longitudinal evaluation. External radiotherapy, radionuclide therapy, and chemotherapy may have a role in palliation, but have not been proven to have a curative value. Prognostic factors are discussed.

Animals↗

PubMed1984

Chromosome 20 deletion in human multiple endocrine neoplasia types 2A and 2B: a double-blind study.

Multiple endocrine neoplasia type 2A and 2B (MEN-2A and MEN-2B) are autosomal dominantly inherited syndromes in which medullary thyroid cancers are associated with adrenal pheochromocytomas. A double-blind analysis of high-resolution G-banded chromosomes was performed on blood specimens from patients in four MEN-2A families and five MEN-2B (mucosal neuroma phenotype) families and from control subjects. Excluding studies on duplicate blood specimens, 9 of 11 control subjects were scored as having normal chromosomes 20, and 11 of 14 MEN-2 patients were scored as having chromosomal deletion: del(20)(p12.2p12.2) (phi 2 = 9.00; P less than 0.001). Two new mutant MEN-2B patients had apparently normal chromosomes 20. These findings demonstrate that the dominant mutation in most MEN-2A and MEN-2B families is a visible chromosome deletion within band 20p12.2.

Adrenal Gland Neoplasms↗

PubMed1998

A new hot spot for mutations in the ret protooncogene causing familial medullary thyroid carcinoma and multiple endocrine neoplasia type 2A.

One hundred and eighty-one families with multiple endocrine neoplasia type 2A (MEN-2A) or familial medullary thyroid carcinoma (FMTC) have been investigated for mutations in the ret protooncogene in Germany. In 8 families with FMTC or MEN-2A, no mutation could be detected in the cysteine-rich domain encoded in exons 10 and 11 of the ret protooncogene. DNA sequencing of additional exons (no. 13-15) revealed rare noncysteine mutations in 3 families (codons 631, 768, and 844). In contrast to these rare events, heterozygous missense mutations in exon 13, codons 790 and 791, were found in 5 families (4 with MTC only; 1 family with MTC and pheochromocytoma) and 11 patients with apparently sporadic tumors. Two different mutations in codon 790 (TTG-->TTT, TTG-->TTC; Leu790Phe) and one mutation in codon 791 (TAT-->TTT; Tyr791Phe) created a phenylalanine residue. We conclude that codons 790 and 791 of the ret protooncogene represent a new hot spot for FMTC/MEN-2A causing mutations. With the discovery of these considerably common mutations in codons 790 and 791 and the identification of some rare mutations, 100% of the German FMTC/MEN-2A families could be characterized by a mutation in the ret protooncogene.

Adult↗

PubMed1992

Long-term follow-up of a large North American kindred with multiple endocrine neoplasia type 2A.

BACKGROUND: Sixty-one patients with multiple endocrine neoplasia (MEN) type 2A (27 men; 34 women; mean age, 39 years) from a single kindred (76 affected, 49 at risk) were followed 1 month to 33 years (median, 14 years) after diagnosis for disease expression. METHODS: Peripheral basal and pentagastrin-stimulated calcitonin, parathyroid hormone, and calcium levels were measured in 60 patients, 58 of whom had undergone previous thyroidectomy; the calcitonin concentration in four patients was concomitantly determined in the hepatic and internal jugular veins. Biochemical or radiographic screening for pheochromocytoma was performed in 58 patients. RESULTS: Recurrence of medullary thyroid carcinoma (MTC) developed in nineteen (33%) of 58 patients after they underwent thyroidectomies. In 14 of 19 patients regional metastases were inapparent at initial operation, and lymphadenectomy was not undertaken. Three patients underwent neck reexploration with removal of micrometastases after selective venous studies were performed. One patient, 33 years of age, died of MTC, and two patients who refused thyroidectomy are alive at 76 and 83 years of age. Fifteen patients are alive with disease 8 to 33 years after they underwent thyroidectomies. All patients identified by prospective screening remain pentagastrin negative. Pheochromocytoma developed in six patients (10%), and four patients have Hirschsprung's disease. Hyperparathyroidism was present in seven patients and did not occur in those with minimal MTC. CONCLUSIONS: These observations suggest that (1) the course of MTC in MEN 2A is highly variable, (2) early treatment of C-cell disease can be curative, (3) routine lymphadenectomy for occult micrometastases may be necessary for cure of MTC, and (4) the hyperparathyroidism of MEN 2A may not be a primary genetic event.

Adolescent↗

PubMed1994

Medullary thyroid carcinoma in multiple endocrine neoplasia types 2A and 2B.

BACKGROUND: Considerable emphasis has been placed on early diagnosis and surgery for multiple endocrine neoplasia (MEN)-related medullary thyroid carcinoma (MTC) during the past two decades. Genetic screening now promises earlier and more accurate diagnosis. We examine our experience with MTC in MEN 2A and MEN 2B and assess the benefits of biochemical screening during the past 20 years. PATIENTS AND METHODS: Seventy-seven patients undergoing 63 primary total thyroidectomies and 14 reoperative procedures for MEN-related invasive MTC and/or preinvasive C-cell hyperplasia are reported. Fifty-eight patients had MEN 2A and 19 had MEN 2B; 79% of patients had a family history of MTC; 27% had pheochromocytoma, and 25% had hyperparathyroidism. RESULTS: Patients with MEN 2B had more advanced disease than those with MEN 2A, in spite of presentation at a younger age (15 years versus 24 years). Every patient with MEN 2B had invasive carcinoma, whereas 14% of patients with MEN 2A had C-cell hyperplasia without invasive disease. Nodal metastases were found less frequently in MEN 2A (14%) than MEN 2B (38%), and biochemical cure was achieved in 56% of patients with MEN 2A compared with none in patients with MEN 2B. Among patients with MEN 2A the occurrence of invasive carcinoma increased with age (p = 0.0003); 40% of patients for less than 5 years had invasive MTC compared with 100% at more than 20 years. Cause-specific mortality among patients with MEN and invasive tumors at 6, 12, and 18 years was 2%, 4%, and 7%, respectively, lower than that of patients with sporadic MTC (12%, 17%, and 23%, respectively) treated during the same time period (p = 0.028). CONCLUSIONS: Intensive biochemical screening of MEN 2 kindreds for MTC can result in detection of early disease and a significant prospect of surgical cure. Genetic testing promises additional benefits through more reliable detection of preinvasive disease, allowing prophylactic thyroidectomy in infancy. In MEN 2B, MTC is considerably more aggressive than in MEN 2A. A policy of routine thyroidectomy in infants with MEN 2B, regardless of serum calcitonin levels, is justified.

Adolescent↗

PubMed1996

C618R mutation in exon 10 of the RET proto-oncogene in a kindred with multiple endocrine neoplasia type 2A and Hirschsprung's disease.

The cosegregation of multiple endocrine neoplasia (MEN) type 2A with Hirschsprung's disease (HSCR), two diseases associated with mutation of the RET proto-oncogene, is infrequent. A 30-yr-old man was referred for screening of MEN 2A. Surgery for HSCR was performed at 4 yr of age. Basal and pentagastrin-stimulated calcitonin levels were abnormal. Histological examination of the thyroid confirmed bilateral medullary thyroid carcinoma. Screening of family members revealed six subjects with medullary thyroid carcinoma or abnormal pentagastrin-stimulated calcitonin test; one had an unilateral pheochromocytoma and two were affected with HSCR. DNA sequence analysis showed a heterozygote C618R mutation in exon 10 of the RET proto-oncogene in the proband and his mother, as well as in second-degree relatives with MEN 2A phenotype or HSCR. In this study, we report on a novel kindred with MEN 2A and HSCR phenotype associated with a point mutation (C618R) in one of the cysteine codons at the extracellular domain of the RET proto-oncogene.

Adult↗

PubMed1993

Prevalence of pheochromocytoma and hyperparathyroidism in multiple endocrine neoplasia type 2A: results of long-term follow-up.

BACKGROUND: Multiple endocrine neoplasia type 2A (MEN 2A) is an autosomal dominant condition in which virtually all affected kindred members have medullary thyroid carcinoma (MTC). However, the penetrance of pheochromocytoma and hyperparathyroidism in affected kindred members is variable, and the true prevalence of these neoplasms is unclear from previous studies. METHODS: Members of MEN 2A kindreds with more than 10 years of follow-up screening for MTC, pheochromocytoma, or hyperparathyroidism were studied. The diagnosis of pheochromocytoma was based on histologic examination and hyperparathyroidism on both parathyroid hyperplasia plus preoperative elevation of serum calcium levels. RESULTS: Eighty-six patients operated on for MTC from 12 different MEN 2A kindreds were studied, with a mean follow-up of 12.9 years of screening for pheochromocytoma (79 patients) and 15.0 years for hyperparathyroidism (78 patients). Pheochromocytomas developed in 42% of patients with MTC, with a range of 6% to 100% in different kindreds. The prevalence of hyperparathyroidism was 35%, ranging from 0% to 53% between kindreds. The average age at diagnosis of MTC, pheochromocytoma, and hyperparathyroidism was 29, 37, and 36 years, respectively. CONCLUSIONS: We conclude that the penetrance of pheochromocytoma and hyperparathyroidism is variable in different kindreds with MEN 2A but that the overall prevalence of pheochromocytoma approximates 40% and that of hyperparathyroidism 35%.

Adolescent↗

PubMed1989

Pre- and peroperative diagnosis of metastatic pheochromocytoma in multiple endocrine neoplasia type 2a.

A 37-year-old woman with a multiple endocrine neoplasia type 2a underwent bilateral adrenalectomy and total thyroidectomy with parathyroidectomy in 1977. The left-sided pheochromocytoma was considered to be malignant. Seven yr after the initial operation, an enhanced urinary excretion-ratio of N-methyladrenaline/adrenalin suggested the possible presence of either persistent or metastatic pheochromocytoma Iodine-123-labeled metaiodobenzylguanidine scintigraphy (I-123 MIBG) showed a hot spot in the right lung. However, repeated chest-X-rays and computed tomographic scanning of the thorax remained negative. Anatomical localization of the lesion was finally obtained with magnetic resonance imaging. The surgical removal of the small pheochromocytoma was guided by the gamma-ray emission of I-123 MIBG administered iv before the operation. This case report illustrates the usefulness of new analytical methods and of new imaging techniques in the diagnosis and management of metastatic pheochromocytoma.

Adult↗

PubMed1990

The genetic defect in multiple endocrine neoplasia type 2A maps next to the centromere of chromosome 10.

Multiple endocrine neoplasia type 2A (MEN2A) is a rare cancer syndrome that is inherited in an apparently autosomal dominant fashion. Previous linkage studies had assigned the MEN2A locus to chromosome 10 in the pericentromeric region. We recently have described several new easily scorable RFLPs for the chromosome 10-specific alpha satellite DNA (the D10Z1) locus that is known, on the basis of previous in situ hybridization experiments, to lie at the centromere. We report here tight linkage between MEN2A and D10Z1, as demonstrated by a maximum lod score of 12.02 at the recombination frequency of zero (1-lod-unit support interval 0-4 cM), indicating that the genetic defect in MEN2A lies in the immediate vicinity of the centromere. By means of a set of ordered polymorphic DNA markers from the pericentromeric region, multipoint as well as pairwise linkage analyses place the MEN2A locus at the middle of a small region (approximately 11 cM) bracketing the centromere with FNRB (at 10p11.2) and RBP3 (at 10q11.2) on either side, providing further support for the centromeric location of the MEN2A locus. Marked sex difference in recombination frequencies exists in this pericentromeric region: significantly (P less than .01) more female than male crossovers were observed across all of the adjacent intervals D10S24-FNRB, FNRB-D10Z1, and D10Z1-RBP3. However, a sex difference was not seen in the 7-cM interval from RBP3 to D10S5, suggesting that large variation in the sex difference in recombination can occur over small chromosomal regions.(ABSTRACT TRUNCATED AT 250 WORDS)

Centromere↗

PubMed1996

Surgical management of hyperparathyroidism in patients with multiple endocrine neoplasia type 2A.

BACKGROUND: The surgical management of hyperparathyroidism in patients with multiple endocrine neoplasia type 2A (MEN 2A) is controversial. We report the long-term follow-up, mutational analysis, and surgical outcome in a large group of patients with MEN 2A and hyperparathyroidism. METHODS: Clinical and genetic data for MEN 2A patients with biochemically and pathologically confirmed hyperparathyroidism and a minimum of 5 years of follow-up were analyzed retrospectively, and outcomes after surgical management were compared. RESULTS: Thirty-five (29%) of 119 patients from 14 MEN 2A kindreds had biochemical and pathologic evidence of hyperparathyroidism, with a mean follow-up of 14.7 years. The phenotypic expression of hyperparathyroidism was associated with germline mutations of the RET protooncogene at codons 634 and 618. At initial operation, 21 (62%) patients had a selective resection, eight (24%) had a subtotal resection, five (14%) had total parathyroidectomy with autotransplantation, and one had an inadvertent total parathyroidectomy. Twenty-seven (77%) patients were cured by the first operation. Persistent hyperparathyroidism occurred in three (8.6%) patients, and recurrent hyperparathyroidism occurred in five (14.3%) patients; both occurred only in patients treated with selective or subtotal resection. Permanent postoperative hypoparathyroidism occurred in six (21%) of 29 patients after selective or subtotal resection, in the one patient with inadvertent total parathyroidectomy, and in one (20%) of 5 patients treated with total parathyroidectomy and autotransplantation. CONCLUSIONS: Recurrent or persistent hyperparathyroidism occurs after selective or subtotal parathyroidectomy, as a result of either missed glands or interval development of neoplasia in previously normal parathyroid glands left in situ. Therefore we advocate total parathyroidectomy and heterotopic autotransplantation for patients with hyperparathyroidism and MEN 2A.

Adolescent↗

PubMed2000

Simultaneously occurring liver metastases of pheochromocytoma and medullary thyroid carcinoma--a diagnostic pitfall with clinical implications for patients with multiple endocrine neoplasia type 2a.

Malignant pheochromocytoma is an exceptional complication in patients with Multiple Endocrine Neoplasia Type 2a (MEN2a). In this paper, we report on a 53-year-old male patient with an evident RET gene germline mutation, who simultaneously developed hepatic metastases of medullary thyroid carcinoma (MTC) and pheochromocytoma. Comprehensive immunohistochemical investigations were performed to elaborate markers which could be useful for differentiating between MTC metastases and pheochromocytoma, respectively. Calcitonin and CEA, in particular cytokeratins and trefoil factor family 1 (TFF1), were detectable exclusively in MTC, whereas all the other markers revealed a comparable expression in both MTC and pheochromocytoma. The only clues that could indicate a potential malignant course were size, a lack of sustentacular cells and hyaline globules, and a focal spindle cell pattern in pheochromocytoma. Owing to a wide agreement in cellular differentiation and a lack of specific, routinely applicable markers for pheochromocytomas, a comprehensive and goal-directed immunohistochemistry is required to rule out pheochromocytoma metastasis in patients with MEN2a. A misinterpretation could lead to harmful clinical complications, as shown in the present case.

Adrenal Gland Neoplasms↗

PubMed2004

Phenotypic expression of a family with multiple endocrine neoplasia type 2A due to a RET mutation at codon 618.

BACKGROUND: Multiple endocrine neoplasia type 2A (MEN2A) is caused by missense mutations in the RET proto-oncogene on chromosome 10. This paper reports the phenotypic expression of a family with MEN2A, in which serine substitutes for cysteine at codon 618 in exon 10 of the RET gene. It was first claimed that medullary thyroid cancer (MTC) with this rare mutation led to mild disease; this has recently been updated to intermediate-high risk, based on stratified genetic information. METHODS: The family was mapped over six generations. In 1971 family members were invited to join a screening programme. Genetic testing was started in 1994. RESULTS: Twenty-two individuals with MTC were identified, 16 by the screening programme. One screened patient had a phaeochromocytoma and four had hyperparathyroidism. At surgery for MTC 12 patients had local tumour metastases and two young patients also had liver metastases. No screened patient died from MTC during a mean observation time of 19 years. Six other family members were diagnosed with MTC by signs and symptoms, five of whom died from MTC. CONCLUSION: Because of the great interindividual differences in tumour aggressiveness within the family it is impossible to predict whether an individual gene carrier will have an aggressive MTC or not. This unpredictability is an additional argument, besides those obtained in stratified genetic studies, for operating on gene carriers at young age.

Adolescent↗

PubMed1997

Multiple endocrine neoplasia type 2A in a black South African family.

The genetic abnormality of multiple endocrine neoplasia type 2A (MEN 2A) has recently been elucidated. Over 95% of families with MEN 2A have an identifiable mutation of the RET proto-oncogene on chromosome 10. This report describes a black South African woman with MEN 2A in whom a mutation of the RET proto-oncogene was identified. Current genetic knowledge and recent changes in clinical practice are presented, with specific reference to the other family members found to be carrying the mutant RET gene.

Adult↗