Hereditary localized pruritus in affected members of a kindred with multiple endocrine neoplasia type 2A (Sipple's syndrome)

Advances in the management of MEN2: from improved surgical and medical treatment to novel kinase inhibitors

Medullary thyroid carcinoma (MTC), a tumor derived from the neural crest, occurs either sporadically or as the dominant component of the type 2 multiple endocrine neoplasia (MEN) syndromes, MEN2A and MEN2B. The discovery that mutations in the RET protooncogene cause hereditary MTC was of great importance, since it led to the development of novel methods of diagnosis and treatment. For example, the detection of a mutated RET allele in family members at risk for inheriting MEN2A or MEN2B signaled that they would develop MTC, and possibly other components of the syndromes. Furthermore, the detection of a mutated allele created the opportunity, especially in young children, to remove the thyroid before MTC developed, or while it was confined to the gland. The discovery also led to the development of molecular targeted therapeutics (MTTs), mainly tyrosine kinase inhibitors, which were effective in the treatment of patients with locally advanced or metastatic MTC. While responses to MTTs are often dramatic, they are highly variable, and almost always transient, because the tumor cells become resistant to the drugs. Clinical investigators and the pharmaceutical industry are focusing on the development of the next generation of MTTs, which have minimal toxicity and greater specificity for mutated RET.

Notalgia Paresthetica and Multiple Endocrine Neoplasia Syndrome 2A: A Case Report

Notalgia paresthetica is characterized by a hyperpigmented macular pruritic skin lesion most commonly localized unilaterally in the middle and upper back region. This condition has been reported in association with multiple endocrine neoplasia syndrome type 2A (MEN 2A) in several families; it rarely affects children and it may serve as an early marker of MEN 2A. We report a 9-year-old girl diagnosed with MEN 2A and notalgia paresthetica.

Diagnóstico, tratamento e seguimento do carcinoma medular de tireoide: recomendações do Departamento de Tireoide da Sociedade Brasileira de Endocrinologia e Metabologia

Introdução O carcinoma medular de tireoide (CMT) origina-se das células parafoliculares da tireoide e corresponde a 3-4% das neoplasias malignas da glândula. Aproximadamente 25% dos casos de CMT são hereditários e decorrentes de mutações ativadoras no proto-oncogene RET (REarranged during Transfection). O CMT é uma neoplasia de curso indolente, com taxas de sobrevida dependentes do estádio tumoral ao diagnóstico. Este artigo descreve diretrizes baseadas em evidências clínicas para o diagnóstico, tratamento e seguimento do CMT. Objetivo O presente consenso, elaborado por especialistas brasileiros e patrocinado pelo Departamento de Tireoide da Sociedade Brasileira de Endocrinologia e Metabologia, visa abordar o diagnóstico, tratamento e seguimento dos pacientes com CMT, de acordo com as evidências mais recentes da literatura. Materiais e métodos: Após estruturação das questões clínicas, foi realizada busca das evidências disponíveis na literatura, inicialmente na base de dados do MedLine-PubMed e posteriormente nas bases Embase e SciELO – Lilacs. A força das evidências, avaliada pelo sistema de classificação de Oxford, foi estabelecida a partir do desenho de estudo utilizado, considerando-se a melhor evidência disponível para cada questão. Resultados Foram definidas 11 questões sobre o diagnóstico, 8 sobre o tratamento cirúrgico e 13 questões abordando o seguimento do CMT, totalizando 32 recomendações. Como um todo, o artigo aborda o diagnóstico clínico e molecular, o tratamento cirúrgico inicial, o manejo pós-operatório e as opções terapêuticas para a doença metastática. Conclusões O diagnóstico de CMT deve ser suspeitado na presença de nódulo tireoidiano e história familiar de CMT e/ou associação com feocromocitoma, hiperparatireoidismo e/ou fenótipo sindrômico característico, como ganglioneuromatose e habitus marfanoides. A punção aspirativa por agulha fina do nódulo, a dosagem de calcitonina sérica e o exame anatomopatológico podem contribuir na confirmação do diagnóstico. A cirurgia é o único tratamento que oferece a possibilidade de cura. As opções de tratamento da doença metastática ainda são limitadas e restritas ao controle da doença. Uma avaliação pós-cirúrgica criteriosa para a identificação de doença residual ou recorrente é fundamental para definir o seguimento e a conduta terapêutica subsequente.

Multiple endocrine neoplasia type 2 and familial medullary thyroid carcinoma: an update

CONTEXT

Over the last decade, our knowledge of the multiple endocrine neoplasia (MEN) type 2 syndromes MEN2A and MEN2B and familial medullary thyroid carcinoma (FMTC) has expanded greatly. In this manuscript, we summarize how recent discoveries have enhanced our understanding of the molecular basis of these diseases and led to improvements in the diagnosis and management of affected patients.

EVIDENCE ACQUISITION

We reviewed the English literature through PubMed from 2000 to the present, using the search terms medullary thyroid carcinoma, multiple endocrine neoplasia type 2, familial medullary thyroid carcinoma, RET proto-oncogene, and calcitonin.

EVIDENCE SYNTHESIS

Over 70 RET mutations are known to cause MEN2A, MEN2B, or FMTC, and recent findings from studies of large kindreds with these syndromes have clouded the relationship between genotype and phenotype, primarily because of the varied clinical presentation of different families with the same RET mutation. This clinical variability has also confounded decisions about the timing of prophylactic thyroidectomy for MTC, the dominant endocrinopathy associated with these syndromes. A distinct advance has been the demonstration through phase II and phase III clinical trials that molecular targeted therapeutics are effective in the treatment of patients with locally advanced or metastatic MTC.

CONCLUSIONS

The effective management of patients with MEN2A, MEN2A, and FMTC depends on an understanding of the variable behavior of disease expression in patients with a specific RET mutation. Information gained from molecular testing, biochemical analysis, and clinical evaluation is important in providing effective management of patients with either early or advanced-stage MTC.

RET proto-oncogene mutations are restricted to codon 618 in Cypriot families with multiple endocrine neoplasia 2

BACKGROUND

RET germline mutations predispose to the development of inherited cancer syndrome multiple endocrine neoplasia type 2 (MEN2). Several variants of the RET proto-oncogene including G691S and S904S have been suggested to act as genetic modifiers at the age of onset ofMEN2.

AIM

The aim of this study is to characterize clinically and molecularly 7 Cypriot patients with familial medullary thyroid carcinoma (FMTC) and 1 with MEN2A and also to determine the allelic frequencies of the RET variants G691S and S904S.

SUBJECTS AND METHODS

Seven probands from FMTC families and 1 from MEN2A were screened for the presence of RET mutations and the G691S and S904S variants. Additionally, 226 healthy Cypriots, who served as controls were analysed in an attempt to compare the frequencies of G691S and S904S RET variants to those observed in the 8 patients.

RESULTS

The clinical diagnosis of the probands was based on clinical presentation and supported with biochemical findings. The germline C618R mutation of exon 10 was identified in all 8 probands and in 15 relatives from 7 different families. No significant difference in the G691S/S904S variants allele frequencies between patients (4/16 or 25%) and controls (124/452 or 27.4%) was found.

CONCLUSIONS

Mutational screening of the RET gene identified a common mutation (C618R) in all 8 (7 FMTC and 1 MEN2A) unrelated Cypriot patients which may be explained by a founder effect. Additionally, no association of the G691S/S904S variants was linked with the disease.

Familial medullary thyroid carcinoma associated with cutaneous lichen amyloidosis

BACKGROUND

This is a report of a patient with a novel genotype-phenotype relationship of a c804 mutation of the RET proto-oncogene manifesting as medullary thyroid carcinoma (MTC) and cutaneous lichen amyloidosis (CLA).

SUMMARY

Clinical data were obtained for patient appearance and laboratory results. Analyzed were histopathology of the skin lesion and thyroid gland, genetic mutation, and family pedigree. Skin histology and histochemistry were consistent with CLA. Serum calcitonin levels were moderately elevated. Thyroid histology demonstrated a 4 mm focus of MTC. Measurements of serum parathormone, calcium, and plasma metanephrines were normal. DNA analysis demonstrated a mutation in codon 804 of the RET proto-oncogene resulting in a Valine to Methionine (V804M) substitution. Genetic testing in two siblings revealed the same mutation.

CONCLUSIONS

This is the first description of a patient with CLA not associated with a mutation in codon 634. The patient is one of the few with a V804M mutation in whom the clinical expression did not fully conform to the definition of familial MTC.

Medullary thyroid cancer: management guidelines of the American Thyroid Association

BACKGROUND

Inherited and sporadic medullary thyroid cancer (MTC) is an uncommon and challenging malignancy. The American Thyroid association (ATA) chose to create specific MTC Clinical Guidelines that would bring together and update the diverse MTC literature and combine it with evidence-based medicine and the knowledge and experience of a panel of expert clinicians.

METHODS

Relevant articles were identified using a systematic PubMed search and supplemented with additional published materials. Evidence-based recommendations were created and then categorized using criteria adapted from the United States Preventive Services Task Force, Agency for Healthcare Research and Quality.

RESULTS

Clinical topics addressed in this scholarly dialog included: initial diagnosis and therapy of preclinical disease (including RET oncogene testing and the timing of prophylactic thyroidectomy), initial diagnosis and therapy of clinically apparent disease (including preoperative testing and imaging, extent of surgery, and handling of devascularized parathyroid glands), initial evaluation and treatment of postoperative patients (including the role of completion thyroidectomy), management of persistent or recurrent MTC (including the role of tumor marker doubling times, and treatment of patients with distant metastases and hormonally active metastases), long-term follow-up and management (including the frequency of follow-up and imaging), and directions for future research.

CONCLUSIONS

One hundred twenty-two evidence-based recommendations were created to assist in the clinical care of MTC patients and to share what we believe is current, rational, and optimal medical practice.

Management of medullary thyroid carcinoma

Medullary thyroid carcinoma (MTC) is responsible for 13.4% of the total deaths attributable to thyroid cancer in human beings and research on MTC over the last 40 years has identified the RET proto-oncogene as a very relevant component of development of both sporadic and hereditary MTC. An activating germline RET proto-oncogene mutation responsible for a multiple endocrine neoplasia syndrome type 2 (MEN2) or a familial hereditary MTC syndrome is carried by 25% to 35% of patients with MTC. The recognition of RET proto-oncogene mutations by genetic sequencing has allowed us to differentiate hereditary from sporadic MTC, so that it is now possible to identify and treat children at risk for this disease before development of metastasis. Thanks to this discovery, we can now establish the association of MTC with other tumors in the context of MEN2 syndrome; determine adequate follow-up, prognosis, and treatment for patients with hereditary disease; and use this information to develop new therapies against both sporadic and hereditary MTCs.

The multiple endocrine neoplasia syndromes

Multiple endocrine neoplasia (MEN) type 1 and type 2 exhibit an autosomal dominant pattern of inheritance. In the past two decades the germline mutations that cause these inherited syndromes have been identified. The large majority of patients with MEN1 have mutations in the menin gene. Mutations in the REarranged during Transfection (RET) gene cause MEN2A, MEN2B, and familial medullary thyroid carcinoma (FMTC). Specific codon mutations within RET correlate with disease phenotype and severity. Also, children from families with MEN2A, MEN2B, or FMTC, who are found to have inherited a mutated RET allele, can be managed by prophylactic thyroidectomy, thus preventing the development of medullary thyroid carcinoma (MTC), the dominant endocrinopathy in patients with these hereditary syndromes. New insights into the molecular pathway of RET signal transduction are leading to novel targeted therapies in patients with locally advanced or metastatic hereditary MTC.

Multiple cutaneous neuromas and macular amyloidosis associated with medullary thyroid carcinoma

Multiple cutaneous neuromas are rarely seen in dermatology practice. We report a case of multiple cutaneous neuromas, macular amyloidosis (MA), and medullary thyroid carcinoma (MTC) and discuss the interrelationship of the associated conditions. Multiple endocrine neoplasia 2 (MEN 2) is a hereditary syndrome that comprises MEN 2A, MEN 2B, and familial MTC. Germline mutations in the RET proto-oncogene is the underlying cause of the syndrome. MEN 2A and MEN 2B show some common endocrine manifestations including MTC and pheochromocytoma. There are reports of families with MA and MEN 2A. Multiple mucosal neuromas occur in 100% of patients with MEN 2B syndrome. Cutaneous neuromas are infrequently reported in MEN 2B syndrome. Our patient was a heterozygote carrier of GAG-->GAC mutation (Glu 768 Asp) in exon 13, codon 768 of the RET proto-oncogene. We speculate that our patient may represent an unusual presentation of MEN 2B or an overlap of MEN 2A and MEN 2B syndromes or a sporadic MTC case with unusual associations.

Mutation analysis of the RET proto-oncogene and early thyroidectomy: results of a Portuguese cancer centre

BACKGROUND

Evidence that germline mutations in the RET proto-oncogene are the underlying cause of the familial form of medullary thyroid carcinoma (MTC) made it possible to identify gene carriers with a very high degree of accuracy. Aiming to define the mutational profile observed in our patients and to assess gene carriers' compliance with an early surgery, we reviewed results of molecular analysis of RET performed at our institution since 1994.

METHODS

One hundred fifty-eight individuals were screened for germline mutations of the RET proto-oncogene. Seventy-seven patients had apparently sporadic MTC; 8 patients had both MTC and pheochromocytoma or MTC and clinical features of multiple endocrine neoplasia type 2B despite a negative family history; 8 patients were known to belong to affected kindreds; and 65 individuals were at-risk individuals to develop MTC.

RESULTS

A germline mutation in RET was identified in 4% of apparently sporadic MTC patients, in 100% of patients with MTC and pheochromocytoma or MTC and clinical features of multiple endocrine neoplasia type 2B, and in 100% of probands of clinically established kindreds. The most affected codon was 634 (58%) followed by codon 804 (16%). Among at-risk individuals, 49% were identified as gene carriers. Seven individuals were submitted to prophylactic thyroidectomy (mean age, 17.7 +/- 12.5 years; range: 3-42 years), and all but 1 had MTC.

CONCLUSIONS

RET mutational spectrum observed in the present population disclosed a higher frequency of codon 804 mutations than expected. Compliance with an early prophylactic surgery seemed to be influenced not only by medical advice and cultural factors but also by the aggressiveness of disease in gene carriers' families.

Neoplasia endócrina múltipla tipo 2

O termo neoplasia endócrina múltipla tipo 2 (NEM 2) foi sugerido em 1968, por Steiner e cols., para diferenciar a síndrome clínica caracterizada pela presença de carcinoma medular de tireóide (CMT), feocromocitoma e hiperparatireoidismo, então denominada síndrome de Sipple, da síndrome de Wermer ou NEM tipo 1, que acomete as glândulas paratireóides, pâncreas e hipófise. Sizemore e cols. (1974) complementaram a diferenciação através da classificação da NEM 2 em 2 subgupos: pacientes com CMT, feocromocitoma, hiperparatireoidismo e aparência normal (NEM 2A) e pacientes sem acometimento das paratireóides e fenótipo caracterizado por ganglioneuromatose intestinal e hábitos marfanóides (NEM 2B). CMT é usualmente o primeiro tumor a ser diagnosticado. O diagnóstico do CMT determina que seja avaliada a extensão da doença e rastreamento do feocromocitoma e hiperparatireoidismo. O diagnóstico de CMT esporádico ou hereditário é realizado através da análise molecular do proto-oncogene RET. Neste artigo são discutidos os aspectos fisiopatológicos, as anormalidades genéticas e os aspectos clínicos da NEM 2. A abordagem diagnóstica e terapêutica nos indivíduos afetados, carreadores assintomáticos e familiares em risco também são discutidos. Os avanços relacionados ao rastreamento genético e intervenção precoce permitiram uma melhoria no prognóstico a longo prazo. No entanto, ainda não dispomos de tratamento eficaz para doença metastática.

Lessons from genes mutated in multiple endocrine neoplasia (MEN) syndromes

Multiple endocrine neoplasia (MEN) types 1 and 2 syndromes are rare hereditary cancer syndromes expressing a variety of endocrine and non-endocrine neoplasias and lesions. The improving of both molecular and clinical genetics knowledge helps health care providers in the whole spectrum of the clinical managements of MEN patients. The MEN1 gene, a tumour suppressor gene, is responsible of MEN1 syndrome, and is probably involved in the regulation of several cell functions, including DNA replication and repair and transcriptional machinery. RET proto-oncogene encodes for a receptor tyrosine kinase protein whose expression is fundamental for appropriate migration, development and differentiation of neuroendocrine cells originating from neural crest. Currently, DNA testing makes possible the early identification of germline mutation in asymptomatic mutant gene carriers in both MEN syndromes. Consequently, the combination of new genetic and diagnostic tools could permit a precocious detection of MEN-associated neoplasms, and in particular the identification of a strong genotype-phenotype correlations in MEN2 syndrome demonstrates an improving outcome and quality of life for affected subjects.

Multiple endocrine neoplasia type 2A/localized cutaneous lichen amyloidosis associated with malignant pheochromocytoma and ganglioneuroma

We hereby present a rare variant of multiple endocrine neoplasia type 2A (MEN2A) associated with a rare skin disease primary cutaneous lichen amyloidosis and discrete malignant pheochromocytoma in both adrenal glands and pancreatic tail, and interestingly accompanied ganglioneuroma located in retroperitoneum in a 34-yr-old female. The presence of composite tumor of pheochromocytoma and ganglioneuroma arising in the adrenal glands has been described previously in MEN2A and in sporadic cases. The patient displayed classical signs and symptoms of catecholamine excess. Biochemical screening proved pheochromocytoma. Computed tomography revealed multiple mass lesions in both adrenal glands. It also showed a large heterogeneous mass that clearly discriminated from right adrenal gland in retroperitoneal location. After surgical exploration, both adrenal glands and the suspicious mass in pancreatic tail were removed successfully together with subtotal resection of the retroperitoneal tumor. Histopathologic examinations confirmed the presence of pheochromocytoma in both adrenal glands as well as pancreatic lesion. A retroperitoneal ganglioneuroma was also present. Symptomatic and biochemical evidence of pheochromocytoma subsided after the operation. Further evaluation for medullary thyroid carcinoma and primary hyperparathyroidism confirmed MEN2A. Mutation analysis of the ret proto-oncogene revealed a missense point mutation at position 634 in exon 11, which gives rise to the substitution of a cysteine codon with a tyrosine residue.

Description of the first two seemingly unrelated Greek Cypriot families with a common C618R RET proto-oncogene mutation

Germ-line mutations of the RET proto-oncogene cause three different cancer syndromes: multiple endocrine neoplasia type 2A (MEN2A), multiple endocrine neoplasia type 2B, and familial medullary thyroid carcinoma (FMTC). The objective of the present study was the clinical and molecular characterization of the first two Greek Cypriot families diagnosed with MEN2A and FMTC. The clinical diagnosis of the probands was based on clinical presentation and supported with laboratory findings (calcitonin and carcinoembryonic antigen tumor marker levels). We screened the RET gene by direct DNA sequencing of exons 10, 11, and 16 using genomic DNA as templates. After identification of the mutation, we also developed the amplification refractory mutation system (ARMS) as an alternative method to direct sequencing for genetic diagnosis of 22 additional individuals from both families. We identified the germ-line missense mutation T --> C of codon 618 of exon 10 (C618R) in the probands of both families. By using ARMS, two members of the MEN2A family and five members of the FMTC family were also found positive for the C618R mutation. These are the first seemingly unrelated families in Cyprus investigated clinically and molecularly in detail and shown to transmit this common RET proto-oncogene mutation.

Hereditary cancer syndromes of the skin

Hereditary cancer syndromes are a group of disorders characterized by a genetic susceptibility to the development of malignant tumors. Multiple cancers in the family or an abnormally early onset for the given cancer may suggest an underlying inherited predisposition. Awareness of their associated dermatologic manifestations can facilitate early detection of risk for neoplasms. This article provides an update on the clinical features, diagnostic criteria, and the use of genetic analysis in the detection of causative mutations of those hereditary cancer syndromes with cutaneous manifestations.

Hyperparathyroidism and multiple endocrine neoplasia

Multiple endocrine neoplasia (MEN) syndromes comprise the group of heritable endocrinopathies, MEN 1, MEN 2A, and MEN 2B. Primary hyperparathyroidism caused by multiglandular involvement is usually the initial manifestation in MEN 1, occurring in more than 90% of patients. In patients with MEN 2A, hyperparathyroidism develops less commonly and is usually milder than in MEN 1. Advances in genetics and molecular biology aid in confirming the diagnosis and screening relatives who are carriers or at risk for the disease. Surgery plays an important role in the management of hyperparathyroidism in both MEN 1 and MEN 2A,although the timing and extent of surgery are areas of controversy.Long-term follow-up reveals a high rate of recurrent hyperparathyroidism in MEN 1 despite surgical intervention.

Multiple endocrine neoplasia type 2

Multiple endocrine neoplasia type 2 (MEN-2) is a hereditary syndrome that is transmitted in an autosomal dominant pattern. MEN-2A, MEN-2B, and familial medullary thyroid cancer (MTC) comprise the MEN-2 syndrome. A germline mutation in the RET proto-oncogene is responsible for the MEN-2 syndrome. Recent data indicate that in 99% of MEN-2 cases, a germline RET mutation can be identified by genetic testing. The phenotypic variation of MEN-2 is diverse and partly related to the codon and specific point mutation in the RET proto-oncogene. There are increasing data on the genotype-phenotype correlations in patients with MEN-2 and this information should be used for screening at-risk patients and treatment of RET mutation carriers. All patients (especially if young) with MTC or bilateral pheochromocytoma should have a careful family history taken and genetic screening for RET germline mutations. Patients who are RET germline mutation carriers but without clinical or biochemical evidence of MTC should have a prophylactic total thyroidectomy. The optimal age of thyroidectomy should be based on the RET genotype (eg, high-risk mutations within the first year of life, intermediate-risk mutations by 5 years of age, and low-risk mutations by 10 years of age). Patients who are diagnosed with clinical or biochemical evidence of MTC should have a total or a near total thyroidectomy and at least a central neck lymph node dissection. Patients who have pheochromocytoma and a unilateral adrenal tumor on a localizing study should have a unilateral laparoscopic adrenalectomy after preoperative alpha-blockade. However, patients with bilateral adrenal tumors on localizing studies should have bilateral laparoscopic adrenalectomy. A cortical-sparing (subtotal) adrenalectomy may be considered, if technically feasible, to avoid long-term steroid dependence and to reduce the risk of Addisonian crisis. Patients with biochemical evidence of primary hyperparathyroidism should have a bilateral neck exploration and total parathyroidectomy and autotransplantation (30-60 mg of the most normal parathyroid tissue) to the nondominant forearm if asymmetric parathyroid hyperplasia is present. Rarely, patients may have only single-gland disease and excision may be performed if the other parathyroid glands are not found with biopsy to be hyperplastic. All unresected parathyroid glands should be marked with a clip because patients with MEN-2A have a high risk of persistent and recurrent primary hyperparathyroidism. Patients with familial MTC may have not manifested the other features of MEN-2A, thus these patients should have continued follow-up for pheochromocytoma and primary hyperparathyroidism.

Genetic testing in endocrinology: lessons learned from experience with multiple endocrine neoplasia type 2 (MEN2)

Multiple endocrine neoplasia type 2 (MEN2) is a syndrome characterized by medullary thyroid carcinoma (MTC), unilateral or bilateral pheochromocytoma and hyperparathyroidism. Familial MTC (FMTC) is a subvariant of MEN2 in which affected individuals develop MTC without other manifestations of MEN2. The identification of RET proto-oncogene mutations in MEN2 and FMTC have provided a precise method for identifying gene carriers. This review provides a concise discussion of the use of genetic testing in the management of hereditary MTC, discussing the appropriate use of this new technology with an emphasis on early intervention to prevent death or serious morbidity from this disease.

Carcinoma medular de tireóide: aspectos moleculares, clínico-oncológicos e terapêuticos

O carcinoma medular de tireóide (CMT) pode ocorrer na forma esporádica ou familiar. O CMT hereditário é parte das síndromes de neoplasia endócrina múltipla (NEM) 2A e 2B, carcinoma medular de tireóide familiar (CMTF) ou outras formas. Mutações de linhagem germinativa do proto-oncogene RET causam a forma hereditária da neoplasia e os testes genéticos atualmente disponíveis formam a base para o manejo adequado da hereditariedade do tumor, visto que o diagnóstico precoce melhora significativamente o prognóstico no indivíduo afetado e nos carreadores. Nos últimos anos, vários estudos têm demonstrado uma correlação entre mutações codon-específica do RET e os diferentes fenótipos da NEM 2A, que pode, em parte, ser explicada por diferenças na intensidade da indução da dimerização do receptor. No presente artigo, revisamos os avanços nos mecanismos moleculares, diagnóstico e tratamento, bem como relatamos a nossa experiência no manejo dessa forma rara de neoplasia tireoidiana.

Frequent association between MEN 2A and cutaneous lichen amyloidosis

OBJECTIVE

Multiple endocrine neoplasia type 2A (MEN 2A) and familial medullary thyroid carcinoma (FMTC) are genetic diseases due to activating mutations of the RET proto-oncogene. Affected patients develop medullary thyroid carcinoma (100%), in an isolated form (FMTC) or in association with phaeochromocytoma (30-50%), and primary hyperparathyroidism (10-20%) (MEN 2A). The presence of cutaneous lichen amyloidosis (CLA) has been anecdotally described in few families harbouring RET proto-oncogene mutation in codon 634. The aim of the study was to evaluate the incidence of CLA in MEN 2A/FMTC families.

PATIENTS AND DESIGN

Ten MEN 2A/FMTC families were studied and RET gene mutations identified in all. Complete dermatological assessment was carried out in each family member. Skin biopsy for histological studies was performed in patients with CLA.

RESULTS

Among 10 MEN 2A/FMTC families, the presence of CLA was found only in patients belonging to the three families with MEN 2A and RET mutation in codon 634. Nine of 25 patients (36%) with codon 634 mutation presented CLA, though two of them did not show CLA skin lesions but the typical neurological pruritus in the upper back. In all patients, neurological pruritus was present since infancy as a precocious marker of the disorder. The dermatological study of patients with CLA skin lesions added further evidence that pruritus has a pivotal role in the development of CLA, the amyloid deposition being the consequence of repeated scratching. Light microscopy revealed orthokeratotic hyperkeratosis, with elongation of the rete ridges, rare intramalpighian apoptic keratinocytes and deposits of amorphous material in the superficial dermis. Examination under ultraviolet light showed thioflavin T-positive staining, confirming the presence of amyloid in the papillary dermis. The use of Capsaicin at the dilution of 0.025% had a mild efficacy on the cutaneous symptoms.

CONCLUSIONS

Among the members of the three families with MEN 2A and RET 634 mutation, the incidence of CLA was 36%, a figure similar to that reported in the literature for phaeochromocytoma (30-50%) and even higher than that for hyperparathyroidism (10-20%). The present data confirm that CLA is linked to codon 634 RET mutations and is a precocious marker of the disorder.

RET codon 634 mutations in multiple endocrine neoplasia type 2: variable clinical features and clinical outcome

Since the establishment of a protocol for molecular analysis of hereditary medullary thyroid carcinoma (MTC) in southern Brazil, in 1997, 17 independent families with RET germline mutation have been identified. Because neither molecular diagnosis nor the pentagastrin test were available before the establishment of this protocol, we had the opportunity to observe a large number of patients in whom the disease has evolved naturally without medical intervention, namely prophylactic thyroidectomy. We observed a wide spectrum in terms of clinical presentation and natural course of the disease even among genetically related individuals. Sixty-nine individuals from 12 different families presented a codon 634 mutation, the most prevailing missense mutation in our series. The specific mutations identified were C634Y (n = 49), C634R (n = 13), and C634W (n = 7). Individuals with the C634R mutation presented significantly more distant metastases at diagnosis than subjects with the C634Y or C634W mutations (54.5% vs. 19.4% vs. 14.3%, respectively, P = 0.03). Further analysis of the estimated cumulative frequency of lymph node and/or distant metastases by Kaplan-Meier curves showed that the appearance of lymph nodes and metastases occurred later in patients with C634Y than in those with C634R (P = 0.001). Our results suggest that specific nucleotide and amino acid exchanges at codon 634 might have a direct impact on tumor aggressiveness in MEN 2A syndrome.

Early onset of medullary thyroid carcinoma in a kindred with multiple endocrine neoplasia type iia associated with cutaneous lichen amyloidosis

OBJECTIVE

To describe the molecular characterization of a kindred affected by the rare variant of multiple endocrine neoplasia type IIA (MEN IIA) associated with cutaneous lichen amyloidosis and to discuss the clinical implications in the management of this syndrome.

METHODS

A kindred with four affected family members was identified, and DNA analysis was performed by sequencing exon 11 of the RET proto-oncogene. Presymptomatic genetic screening was offered to all first-degree relatives.

RESULTS

Sequencing analysis of the RET proto-oncogene revealed a Cys634Trp (TGC->TGG) mutation in all clinically affected family members and in an asymptomatic 5-year-old child who, after thyroidectomy, was found to have multicentric medullary thyroid carcinoma and C-cell hyperplasia. A Gly691Ser (GGT->AGT) polymorphism was also detected in this family but did not segregate with the disease.

CONCLUSION

To our knowledge, this is the earliest detection of medullary thyroid carcinoma reported thus far in a kindred with MEN IIA associated with cutaneous lichen amyloidosis, and this finding suggests that prophylactic thyroidectomy, in kindreds with this variant, should be performed before the age of 5 years.

Genetic markers in thyroid neoplasia

Cancer is a disease of genes. Detection of genetic abnormalities associated with cancers of various cell types can now be used for genetic counseling, diagnosis or treatment selection. In the case of thyroid cancer, genetic testing for mutations of the RET oncogene has had a profound effect on the management of medullary thyroid carcinomas. There is also considerable information on the genetic changes associated with development and progression of cancers of thyroid follicular cells, although these have not yet proven to be of practical value for clinical diagnosis or to guide prognosis and therapy.

Multiple endocrine neoplasias

The multiple endocrine neoplasia syndromes form a distinct group of genetic tumor syndromes. They include multiple endocrine neoplasia types 1 and 2, von Hippel Lindau syndrome, neurofibromatosis, and Carney complex. Research over the past decade has identified a molecular basis for each of these syndromes. This knowledge has revolutionized not only the clinical management but also has illuminated the field of human cancer research by the identification of new and important genes critical for regulation of cell growth, differentiation, and death. This review focuses on the structure, physiologic function, and molecular abnormalities of the genes involved in these syndromes.

A Cys634Gly substitution of the RET proto-oncogene in a family with recurrence of multiple endocrine neoplasia type 2A and cutaneous lichen amyloidosis

Germ-line mutations of the RET proto-oncogene, involving five cysteine residues at codons 609, 611, 618, 620 and 634, are associated with two variants of the inherited cancer syndrome multiple endocrine neoplasia type 2: type 2A and familial medullary thyroid carcinoma. The association of multiple endocrine neoplasia type 2A with the dermatological disorder cutaneous lichen amyloidosis has already been reported, and mutations in the Cys634 have been identified in different families. We describe here an additional pedigree in which multiple endocrine neoplasia type 2A and cutaneous lichen amyloidosis cosegregate. A Cys634Gly was identified by direct sequencing of the RET proto-oncogene exon 11 in the affected individuals. The mutation creates a new HaeIII site, and restriction analysis performed on all family members rules out the presence of the altered allele in two children and consequently the risk of developing thyroid tumors. These results emphasize the role of molecular analysis of the RET proto-oncogene in diagnosing presymptomatically those individuals at risk of inheriting the disease allele.

Multiple endocrine neoplasia type II and familial medullary thyroid carcinoma. Impact of genetic screening on management

The identification of ret protooncogene mutations in MEN-II and Hirschsprung disease has not only improved the clinical management of these genetic conditions but has also provided important information regarding mechanisms of transformation and neural crest development. An indication of how neural-crest cells migrate during embryonic life and the key processes involved in their differentiation now seems within reach. The continued pace of scientific discovery suggests that our understanding of and ability to prevent or treat hereditary and sporadic forms of MTC will continue to improve.

RET mutation screening in familial cutaneous lichen amyloidosis and in skin amyloidosis associated with multiple endocrine neoplasia

In several families, multiple endocrine neoplasia type 2A (MEN 2A) has been found in association with cutaneous lichen amyloidosis. It has been debated, however, whether the skin amyloidosis found in MEN 2A families, localized exclusively in the interscapular area, represents the same anomaly as that found in autosomal dominant familial cutaneous lichen amyloidosis, which is more generalized. We screened two MEN 2A families with associated skin amyloidosis for germline mutations in the RET gene responsible for the MEN 2A cancer syndrome, and found the same mutation characteristic of MEN 2A in both families. We also screened probands from three pedigrees with familial cutaneous lichen amyloidosis for RET mutations. In none of the RET coding and flanking intronic sequences was a mutation detected. This most probably indicates that skin amyloidosis found in some MEN 2A families and familial cutaneous lichen amyloidosis are different conditions. Consequently, patients with apparent familial cutaneous lichen amyloidosis do not appear to be at risk for MEN 2A.

Genetic heterogeneity of familial primary cutaneous amyloidosis: lack of evidence for linkage with the chromosome 10 pericentromeric region in Chinese families

Primary cutaneous amyloidosis is a relatively common skin disease in Southeast Asia, South America, and the Republic of China. Although most cases are sporadic, some patients have a family history, suggesting that genetic factors may play a role in its pathogenesis. Some patients with multiple endocrine neoplasia type 2A also have a clinical picture of primary cutaneous amyloidosis. It is thus suggested that the gene of familial primary cutaneous amyloidosis is linked to the pericentromeric region of chromosome 10, the location of the RET proto-oncogene. We have carried out linkage analysis in seven families with cutaneous amyloidosis using four dinucleotide repeat markers from the RET region. Negative lod scores at all recombination frequencies were obtained. We thus conclude that there is no evidence for linkage between Chinese families with primary cutaneous amyloidosis and the pericentromeric region of chromosome 10. The distinct genetic basis, plus their apparent phenotypic differences in sex ratio, age of onset, and sites of cutaneous lesions, suggests that familial primary cutaneous amyloidosis includes clinical subtypes attributable to genetic heterogeneity.

Application of genetic screening information to the management of medullary thyroid carcinoma and multiple endocrine neoplasia type 2

Application of RET proto-oncogene mutation analysis to the clinical management of MEN 2 and FMTC has simplified and enhanced the power of earlier used screening and treatment efforts for hereditary MTC. The approaches outlined herein are cost-effective, have improved diagnostic accuracy, and hold the promise of improved cure rates for this neoplasm. Further studies to elucidate the mechanism by which these activating mutations cause transformation may lead to other strategies for prevention or treatment of this neoplasm.

Putting the bits and pieces of the RET proto-oncogene puzzle together

The RET proto-oncogene has been implicated in the causation of papillary thyroid carcinoma, multiple endocrine neoplasia types 2A (MEN 2A) and 2B (MEN 2B), and Hirschsprung's disease. The mutations in these syndromes can be categorized into activating or inactivating mutations. Activating mutations of a cysteine-rich extracellular region cause enhanced dimerization of the RET tyrosine kinase receptor and autophosphorylation, and are causative for MEN 2A and familial medullary thyroid carcinoma (FMTC). An activating mutation of the tyrosine kinase domain causes increased autophosphorylation but does not affect the state of dimerization. A variety of inactivating mutations of the RET proto-oncogene, which result in defective protein formation, are causative for Hirschsprung's disease.

RET proto-oncogene mutations in multiple endocrine neoplasia type 2 and medullary thyroid carcinoma

The identification of RET proto-oncogene mutations in patients with MEN2 2 years ago was a watershed event in the management of this genetic cancer syndrome. The identification of a finite number of mutations that together causes more than 95% of hereditary and 15-25% of sporadic MTC has made it possible to develop simple and definitive tests to screen individuals at risk for this tumour syndrome. The impact of this technology is enormous. It is now possible to reassure 50% of family members at risk that they, and their children, do not have to worry about developing MTC. In the other 50% who are gene carriers, it is now possible to approach clinical management with greater certainty and plot strategies that are likely to result in a greater percentage of curative therapy. It seems likely that this technology will also have an impact on the management of sporadic MTC, although it is still too early to define a specific role for mutational analysis in these patients, except to exclude hereditary disease. The identification of specific mutations causative for MTC makes it possible to conceive future strategies for the treatment or prevention of MTC and to further extend the impact of these exciting findings.

Identification of the Cys634-->Tyr mutation of the RET proto-oncogene in a pedigree with multiple endocrine neoplasia type 2A and localized cutaneous lichen amyloidosis

Following the recent identification of specific germline mutations of the RET proto-oncogene in Multiple Endocrine Neoplasia type 2A (MEN2A) patients, we looked for mutations of this gene in a pedigree showing recurrence of MEN2A and localized Cutaneous Lichen Amyloidosis (CLA). Basal calcitonin and/or pentagastrin test performed in all the 10 available members of this pedigree confirmed the clinical diagnosis and allowed the presymptomatic identification of an additional carrier. A cys634-->tyr missense mutation, already reported as causative in MEN2A patients, was identified after SSCP analysis and direct sequencing of exon 11 of the RET protooncogene in one individual affected with both MEN2A and CLA, thus suggesting a common etiology for the two disorders. Taking advantage of the observation of an RsaI restriction site in the sequence surrounding the mutated codon, we could demonstrate that the same mutation is present in three other affected members, in the presymptomatic carrier and in one additional 25 years old healthy member who shows a mildly positive pentagastrin test.

Multiple endocrine neoplasia type 2A and cutaneous lichen amyloidosis: description of a new family

Multiple endocrine neoplasia (MEN) 2A associated to cutaneous lichen amyloidosis is a variant of MEN 2A recently reported in few families. We describe an additional family with this syndrome. The skin lesion is a pruritic one, located over the upper back showing, at biopsy, cutaneous amyloid. The propositus of our family was a 35-year-old woman already treated with total thyroidectomy for medullary thyroid cancer and with bilateral adrenalectomy for pheochromocytoma. The patient referred that the skin lesion was present since childhood and increased with time. Skin biopsy showed negative staining for amyloid, for calcitonin and neuron-specific enolase. The paraspinal muscles corresponding to the area of affected skin showed slight neurogenic abnormalities. Ten other members of her family were affected by MEN 2A, three of whom (all females) had the same cutaneous alteration.

A kindred with multiple endocrine neoplasia type 2A associated with pruritic skin lesions

BACKGROUND

A kindred affected by multiple endocrine neoplasia type 2A (MEN 2A), associated with symmetric, bilateral, scapular pruritic skin lesions (PSL), is reported.

METHODS

There were 21 members, including the propositus, in four generations. Screening of 10 family members showed a palpable thyroid tumor in 1 and positive results for a pentagastrin test in 7 others. Two of these patients had surgically confirmed pheochromocytoma. Two others had a biochemical diagnosis of pheochromocytoma but did not have surgery.

RESULTS

Medullary thyroid carcinoma was confirmed in five patients and nodular C-cell hyperplasia in another. In five affected adults, PSL were observed in the interscapular region, crossing the midline in some. These lesions were characterized by hyperkeratosis and hyperpigmentation. In all the patients, the pruritus had been present long before the clinical or biochemical diagnosis. Skin biopsies were performed in two of these patients. No amyloid deposits were found (Congo red stain and electron microscopic examination were used). Two children (14 and 6 years old) in the fourth generation complained of scapular pruritus, although skin lesions were not apparent.

CONCLUSIONS

Localized PSL must be sought when screening for MEN 2A.

Sipple syndrome with lichen amyloidosis as a paracrinopathy: pleiotropy, heterogeneity, or a contiguous gene?

A five-generation white family with multiple endocrine neoplasia type 2A had six affected members. Two, a mother and her daughter, had interscapular cutaneous pruritic lesions resembling macular/lichen amyloidosis. In the daughter, light microscopy showed homogeneous aggregates in the papillary dermis. Crystal violet staining showed metachromasia and indicated that the deposits were amyloid. This is the fourth family with familial medullary thyroid carcinoma with cutaneous amyloidosis and as such it allowed comparative analysis. Genetic heterogeneity, a contiguous gene, and pleiotropy were considered. It appears that multiple endocrine neoplasia type 2A/familial medullary thyroid carcinoma with cutaneous amyloidosis represents the phenotypic variability of the expression of a pleiotropic gene. The condition is one of the predominantly ectodermal autosomal dominant phakomatoses and is most likely a paracrinopathy.

Primary localized cutaneous amyloidosis and familial medullary thyroid carcinoma

We have studied a family with an autosomal dominant inheritance of primary localized cutaneous amyloidosis (PLCA) and familial medullary thyroid carcinoma (MTC). Ten family members were screened for multiple endocrine neoplasia (MEN) 2; five were found to have MTC and two had C-cell hyperplasia. None had evidence of phaeochromocytoma or parathyroid abnormalities. Five of these seven patients presented characteristic interscapular hyperpigmented lesions, showing dermal amyloid deposits in two of the four patients in which a biopsy was performed. The data are analysed in the light of two recent reports of MEN 2A associated with identical lesions. We conclude that PLCA should be sought in MTC patients, even if no other endocrinopathies are present. This may be informative of the familial character of MTC in index cases and also of the tumour gene status in family members who are being screened.

The impact of gene mapping techniques on the management of multiple endocrine neoplasia type 2

There has been sustained progress toward the identification of the gene for multiple endocrine neoplasia type 2. Closely linked and flanking DNA markers have been identified, and it is now possible to assign gene carrier status in informative families at risk with a >90% certainty by the use of molecular genetic techniques. Application of-these techniques, however, requires an understanding of their current limitations and caution in their use of clinical decision making.