A novel germline mutation of multiple endocrine neoplasia type 1 (MEN1) gene in a Japanese MEN1 patient and her daughter

Familial multiple endocrine neoplasia type 1 (MEN1) is an autosomal dominant inherited disorder characterized by tumors of the parathyroid, anterior pituitary and gastro-entero-pancreatic endocrine tissues. The MEN1 gene has recently been cloned and its germline mutations have been considered to play an important role in the tumorigenesis of MEN1. We analyzed a Japanese MEN1 patient and her daughter for germline mutations of the MEN1 gene. The proband (60 y.o.) had primary hyperparathyroidism (PHP) and gastrinoma, and her daughter (30 y.o.) had prolactinoma. Clinical examinations revealed no evidence of PHP in the daughter. We identified a novel heterozygous germline mutation (712 A del) at codon 201 in exon 3 of the MEN1 gene in the proband. Restriction digestion analysis revealed the same mutation pattern in her daughter. These findings suggest that this family has familial MEN1 including a rare case of MEN1 with a single lesion of the pituitary. Genetic examinations are useful as diagnostic tools for any rare or variant case of familial MEN1.

Measurement of the expression of oncofetal fibronectin mRNA in thyroid carcinomas by competitive reverse transcription-polymerase chain reaction

Abundant expression of oncofetal fibronectin mRNA has been observed in thyroid papillary and anaplastic carcinomas. In this study, we measured relative expression levels of oncofetal fibronectin mRNA in thyroid cancer tissues by competitive reverse transcription polymerase chain reaction (RT-PCR) using thyroglobulin mRNA as an internal control. By this method, all papillary and anaplastic carcinomas and 3 of 6 follicular carcinomas were distinguished from benign tissues, such as normal thyroid tissues, follicular adenomas, and adenomatous goiters. Furthermore, 2 anaplastic carcinomas were clearly distinguished from differentiated carcinomas. These results suggest the possibility of establishing a more accurate preoperative or postoperative diagnosis of papillary and anaplastic carcinomas by measuring the relative expression level of oncofetal fibronectin to thyroglobulin in thyroid tumors.

Preoperative diagnosis of medullary thyroid carcinoma by RT-PCR using RNA extracted from leftover cells within a needle used for fine needle aspiration biopsy

Fine needle aspiration Biopsy (FNAB) is commonly used to diagnose thyroid tumors. In some clinical situations, however, accurate diagnosis requires a more objective method than cytological examination alone. Medullary thyroid carcinomas (MTC) derive from C cells in the thyroid and express some specific messenger RNAs (mRNA), such as those transcribed from the RET proto-oncogene, the calcitonin gene, and the gene for carcinoembryonic antigen (CEA), which usually do not exist in normal thyroid follicular cells or thyroid tumors of follicular epithelial descent. Recently, we established a new method for the molecular diagnosis of thyroid tumors without additional invasion to the patient by extracting RNA for RT-PCR from the leftover cells inside the needles used for fine needle aspiration biopsy (Aspiration Biopsy-Reverse Transcription-Polymerase Chain Reaction, ABRP). By applying the ABRP method to the detection of RET, calcitonin, and CEA mRNAs, an accurate molecular-based diagnosis for MTC maybe established as an adjunct to cytological diagnosis. In this study, 35 aspirates were obtained at the time of surgery from thyroid tumors, including 11 MTCs. The expression of these mRNAs in the leftover cells inside the needles used for the aspiration was then examined. Transcripts from all three genes were detected in the samples from all 11 MTCs, but none of these mRNAs were detected in the other tumors or normal thyroid tissues. Furthermore, MTC was preoperatively diagnosed in three patients by ABRP detection of these mRNAs, and these diagnoses were confirmed by subsequent cytological and histopathological analyses. Thus RT-PCR detection of RET, calcitonin, and CEA mRNAs in FNABs may be an efficient molecular adjunct for diagnosing MTC.

Evidence for a potential role for HDL as an important source of cholesterol in human adrenocortical tumors via the CLA-1 pathway

CLA-1, a human homologue of rodent scavenger receptor class B1 (SR-B1), has been identified as a receptor for high density lipoprotein (HDL) and is highly expressed in the adrenal gland. Several studies have indicated that HDL might be a source of cholesterol for steroidogenesis in the adrenal gland. In this study, we show that ACTH and its second messenger cAMP stimulated CLA-1 protein expression in a human adrenocortical cell line. We also determined whether CLA-1 plays an important role in steroidogenesis by investigating CLA-1 expression levels in various adrenal tumors including the adenomas of Cushing's and Conn's syndrome. Western blot analysis showed that CLA-1 expression was much higher in the tumors of Cushing's syndrome than in non-tumor lesions of Conn's syndrome and pheochromocytoma. We were able to detect a strong CLA-1 signal in tumors of Conn's syndrome, too. On the other hand, much less CLA-1 expression was detected in Cushing's adenoma adjacent adrenal glands. The immunohistochemical analysis showed that CLA-1 was expressed in the outer region of the adrenal cortex mainly in plasma membranes of the cortical cells but not in the medulla. These findings demonstrated for the first time that ACTH increased CLA-1 protein in cultured human adrenocortical cells, and that cortisol- and aldosterone-secreting adenomas had high CLA-1 proteins in their cell surfaces.

Comparison of antiresorptive activities of ipriflavone, an isoflavone derivative, and elcatonin, an eel carbocalcitonin

Thirty postmenopausal women with reduced bone mineral density were divided randomly into two groups based on the chronological sequence of their first visit to the Osteoporosis Clinic of Katsuragi Hospital. Group I was given 600 mg ipriflavone orally daily and group II was weekly injected intramuscularly with 20 units elcatonin, Asu1-7 eel calcitonin (carbocalcitonin). Lumbar spine BMD was measured by dual-energy X-ray absorptiometry, and trabecular bone mineral density at the distal radius, cortical bone density, and relative cortical volume at the radial diaphysis by peripheral computed tomography before the beginning of the study and at the 4th, 8th, and 12th month. Markers of bone metabolism--serum total alkaline phosphatase, bone-specific alkaline phosphatase, tartrate-resistant acid phosphatase, osteocalcin, intact osteocalcin, PICP and ICTP, and urinary pyridinoline, deoxypyridinoline, and calcium/creatinine (Ca/Cr)--were also measured at the same interval. Plasma parathyroid hormone (PTH) and calcitonin (CT) were measured at the same time. Radial trabecular bone density showed a significantly higher rate of increase in group I (ipriflavone group) than in group II (elcatonin group) at the 4th month, whereas lumbar spine BMD showed more pronounced increase in the elcatonin group than in the ipriflavone group throughout the study period. Bone metabolism markers tended to decline in both groups. Total and intact osteocalcin showed a significant fall from the baseline throughout the study period only in the ipriflavone group. Urine pyridinoline and deoxypyridinoline showed a significant fall from the baseline at the 12th month only in the ipriflavone group. On comparing bone gainers with increase of lumbar spine BMD by 2% or more with bone losers with a decrease by 2% or more, only urine Ca/Cr was significantly different, lower in the former than in the latter, despite the general tendency for bone resorption markers to decrease in bone gainers and to increase in bone losers.

Two germline missense mutations at codons 804 and 806 of the RET proto-oncogene in the same allele in a patient with multiple endocrine neoplasia type 2B without codon 918 mutation

Multiple endocrine neoplasia (MEN) type 2B is a clinically distinct entity among the autosomal dominant MEN 2 syndromes. Most patients with MEN 2B carry a germline mutation (M918T) of the RET proto-oncogene, while a few carry A883F. We examined a patient with MEN 2B, but without M918T or A883F, and her relatives. Here, we report the presence in this patient of 2 germline mutations, V804M and Y806C in the same allele. While the novel Y806C was inherited from her father, its carriers (her father and brother) was not affected by MEN 2. In contrast, V804M was a de novo mutation, that has been reported in patients with familial medullary thyroid carcinoma. Combinations of mutations of the RET proto-oncogene may cause oncogenic activities different from those of single mutations.

Analysis of splice variants of the fibronectin gene in thyroid carcinomas by reverse transcription-polymerase chain reaction: increased expression of oncofetal fibronectin mRNA in papillary carcinomas is not caused by the alternation in splicing

The expression levels of each splice variant of the fibronectin gene in the normal thyroid and in thyroid tumors were examined by reverse transcription-polymerase chain reaction (RT-PCR). In thyroid papillary carcinomas, insertion of a variant exon in the ED-A and ED-B domains, and three of five types of splice variants in the IIICS domain were observed. In spite of the marked increase in the expression of oncofetal fibronectin mRNA with the IIICS sequence in papillary and anaplastic carcinomas in the previous reports, the relative expression levels of each splice variant with or without the IIICS sequence showed no difference among all the tumor types. Therefore, the much increased expression of oncofetal fibronectin mRNA in these carcinomas is not caused by the alternation in splicing, but may be caused by an increase in promoter activity or stability of mRNA of the fibronectin gene.

A family of MEN1 with a novel germline missense mutation and benign polymorphisms

The gene responsible for multiple endocrine neoplasia type 1 (MEN1) has recently been cloned, and its germline mutations were identified in patients with this syndrome. The majority of the mutations, frameshift or nonsense mutations, are expected to result in a loss of function of the gene product menin. Since the consequence of less common missense or in-frame deletion mutations is not clear, careful judgment is necessary regarding the role(s) of such mutations in MEN1 disease. Here we describe a large multigenerational MEN1 family with a novel germline missense mutation and three benign polymorphisms. The proband was a man with hyperparathyroidism and thymic carcinoid. We performed biochemical studies and DNA analyses of the MEN1 gene simultaneously and independently as family screening studies. Seven patients including the proband were identified, and all of them carried a heterozygous germline missense mutation E45G, but 5 members with normal biochemical results did not. This mutation was not observed in 50 normal volunteers. This novel missense mutation is therefore almost conclusively responsible for the disease. Although all of the mutant gene carriers in the present study already had clinical diseases, an MEN1 gene analysis in younger individuals at risk would be very useful in identifying carriers before the onset of the symptoms.

The role of ansa-to-recurrent-laryngeal nerve anastomosis in operations for thyroid cancer

OBJECTIVE

To study the recovery in phonation after reconstruction of the recurrent laryngeal nerve (RLN) in patients whose thyroid cancer was invading the nerve, and to evaluate the role of ansa cervicalis to RLN anastomosis (ARA) in operations for thyroid cancer.

DESIGN

Retrospective study.

SETTING

University hospital and private thyroid clinic hospital, Japan.

SUBJECTS

34 patients with thyroid cancer who underwent reconstruction of unilateral RLN and 331 consecutive patients operated on for thyroid cancer.

INTERVENTIONS

Reconstruction was direct anastomosis (DA), free nerve grafting (FNG), vagus-RLN anastomosis (VRA) or ARA, including anastomosis behind the thyroid cartilage.

MAIN OUTCOME MEASURES

Maximum phonation time (34 normal subjects and 26 patients with vocal cord paralysis served as controls), laryngoscopic examination, and the ratio of reconstruction in patients who needed resection of the RLN.

RESULTS

The maximum phonation time started to increase rapidly 2-5 months postoperatively in most cases as the patients' voices recovered, and 12 months after reconstruction was significantly longer than in those patients with vocal cord paralysis (P < 0.0001). It was comparable to that of the normal subjects, although the reinnervated cords were fixed in the median. The number of reconstructions in the series of 331 patients increased from 18% to 82% after we started doing ARA with the meticulous technique of anastomosis inside the thyroid cartilage.

CONCLUSIONS

ARA is as effective as DA or FNG in improving phonation in patients who need resection of a unilateral RLN. As ARA has several advantages over FNG it has a definite place in operations for thyroid cancer.

Germline mutation of the multiple endocrine neoplasia type 1 (MEN1) gene in a family with primary hyperparathyroidism

Familial primary hyperparathyroidism (FHP) is a rare hereditary disorder characterized by isolated parathyroid tumors without any other lesions related to multiple endocrine neoplasia (MEN). Primary hyperparathyroidism is usually expressed at an early age and is highly penetrated in MEN type 1 (MEN1), suggesting that some FHP may be a variant type or early stage of MEN1. The MEN1 gene has recently been cloned and its germline mutations have been considered to play an important role in the tumorigenesis of MEN1. We studied a Japanese family with primary hyperparathyroidism which included 4 patients. To investigate the possible relationship between primary hyperparathyroidism in this family and the MEN1 gene, we analyzed a proband for a germline mutation of the MEN1 gene in this study. We identified a novel heterozygous mutation (1350del3) at codon 414 in exon 9. Restriction digestion analysis revealed the same mutation pattern in his brother with hyperparathyroidism. These findings suggest that our patients may belong to a variant type of MEN1.

Accurate and objective preoperative diagnosis of thyroid papillary carcinomas by reverse transcription-PCR detection of oncofetal fibronectin messenger RNA in fine-needle aspiration biopsies

Recently, the restricted expression of oncofetal fibronectin mRNA was reported in thyroid papillary and anaplastic carcinomas. In this study, by extracting RNA from the leftover cells inside the needles used for fine-needle aspiration biopsy, we establish a new method for gene diagnosis of these carcinomas without further invasiveness to the patient (aspiration biopsy-reverse transcription-PCR, ABRP). RNA was extracted from 177 fine-needle aspiration biopsies of thyroid nodules that were suspicious for malignancy, and then the gene diagnoses made by reverse transciption-PCR detection of oncofetal fibronectin mRNA were compared with cytological diagnoses. Thirty-five (94.6%) of 37 samples that were diagnosed as papillary or anaplastic carcinomas by cytological examination showed a positive result by gene diagnosis, whereas only 4 (3.7%) of 109 samples that were cytologically diagnosed negative for both carcinomas showed a positive result. Among all of the cases, 50 patients underwent surgery, and a histological diagnosis was consequently made. The sensitivity and specificity of this method were 96.9 and 100%, respectively. A combined examination using both genetic and cytological approaches may contribute to a more precise preoperative diagnosis of papillary and anaplastic carcinomas.

Identification of five novel germline mutations of the MEN1 gene in Japanese multiple endocrine neoplasia type 1 (MEN1) families

Multiple endocrine neoplasia type 1 (MEN1) is an autosomal dominant disorder characterised by tumours of the parathyroid glands, the anterior pituitary, and endocrine pancreas. The MEN1 gene has recently been cloned and germline mutations have been identified in MEN1 patients in the United States, Canada, and Europe. We examined MEN1 gene mutations in MEN1 and MEN1 related cases in eight unrelated Japanese families. These families include five familial MEN1 (FMEN1), two sporadic MEN1 (SMEN1), and one familial hyperparathyroidism (FHP). Direct sequence analysis of the protein coding regions was carried out in all the probands. We identified six different heterozygous mutations in the coding region, of which five were novel, including one missense mutation (E45G) in both FMEN1 and SMEN1, three deletions (569del, 711del, and 1350del3) in FMEN1 and FHP, and two nonsense mutations (R29X and Y312X) in FMEN1 and SMEN1. Only one of these mutations (Y312X) has previously been reported. One proband with FMEN1 had no mutation in the entire exon sequence including the 5' and 3' untranslated regions. A restriction digestion analysis of 19 relatives from the five families showed a close correlation between the existence of the MEN1 gene mutation and disease onset. Four different polymorphisms, including two novel ones, were identified. These findings imply that a diversity of MEN1 gene mutations exists in Japanese MEN1 and MEN1 related disease, suggesting that analysis of the entire coding region of the MEN1 gene is required for genetic counselling in Japan.

[A case of stage IV breast cancer showing long-term complete response to combination therapy with 5'-DFUR and MPA]

We report a 62-year-old woman with supraclavicular lymph node, pleural and bone metastases from breast cancer showing a long-term complete response to combination therapy with 5'-DFUR and MPA. A large amount of pleural effusion was drained followed by administration of ADM, which improved the amount of effusion. Treatment with CAF and TAM decreased tumor size, but CAF was abandoned due to severe leukopenia. Mastectomy was performed for local control. However, levels of tumor markers increased progressively. Administration of CMF was tried, but tumor markers continued to increase. Therefore, combined chemoendocrine therapy with 5'-DFUR and MPA was undertaken. Levels of tumor markers normalized and a complete response was obtained 13 months after starting this combination therapy. There are no further metastatic lesions evident, and this status has been consistently maintained for more than three years (six years and five months after diagnosis of breast cancer). There were no significant side effects of this combination therapy except for mild weight gain and moon face. This combination regimen with 5'-DFUR and MPA is considered useful as a second-line treatment for advanced breast cancer.

Genotype-phenotype correlation of patients with multiple endocrine neoplasia type 2 in Japan

BACKGROUND

Multiple endocrine neoplasia type 2 (MEN 2) is a hereditary syndrome characterized by medullary thyroid carcinoma (MTC), pheochromocytoma and hyperparathyroidism. MEN 2 is caused predominantly by germ-line mutations of the RET proto-oncogene. This study aimed to clarify the genotype-phenotype correlation in MEN 2 patients in Japan in order to modify the clinical management according to the genotype.

METHODS

Constitutive DNA of 64 MEN 2 patients (48 kindreds) were searched for mutations at exons 10, 11, 13, 14 and 16 of the RET proto-oncogene using polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP), direct sequencing and restriction enzyme digestion. The clinical characteristics of the patients were obtained from a previous nationwide questionnaire survey.

RESULTS

Overall, 62 (96.9%) out of 64 patients had a germ-line point mutation at the hot spots. MTC and pheochromocytoma occurred equally in every genotype except C630S. Specific genotype had a correlation between tumor size and age at the operation for MTC or extent of MTC, i.e. C618S developed late onset type of MTC as compared with that of C634R, C634Y and M918T. Small MTC in C634R may be less aggressive than those in C634Y and M918T.

CONCLUSIONS

DNA testing has good clinical implications for the management of patients with MEN 2 and the timing and operative procedures of thyroidectomy can be modified according to the genotype.

Immunohistochemical staining for bcl-2 and mcl-1 in intrathyroidal epithelial thymoma (ITET)/carcinoma showing thymus-like differentiation (CASTLE) and cervical thymic carcinoma

Intrathyroidal epithelial thymoma (ITET)/carcinoma showing thymus-like differentiation (CASTLE), a rare thyroid neoplasm, was recently shown to be immunoreactive for CD5, providing immunophenotypic evidence of previously postulated thymic differentiation. To assess whether ectopic malignant neoplasms with thymic differentiation display other markers associated with thymic carcinoma, we studied five cases of ITET/CASTLE, two cases of cervical thymic carcinoma, and one case of cervical thymoma for bcl-2 and mcl-1 immunoreactivity. Both of these antiapoptosis proto-oncogenes have been reported to be expressed by the majority of true thymic carcinomas but only a minority of thymomas. All of the five cases of ITET/CASTLE, both CD5-positive cervical thymic carcinomas, and one CD5-negative cervical thymoma were immunoreactive for bcl-2, as were 10 (91%) of 11 thymic carcinomas arising in the thymus, in contrast to 6 (25%) of 24 benign and invasive thymomas arising in the thymus. Similarly, all of the five cases of ITET/CASTLE, both cervical thymic carcinomas, but not the cervical thymoma, were immunoreactive for mcl-1, as were 9 (90%) of 10 thymic carcinomas, in contrast to 6 (33%) of 18 benign and invasive thymomas. We conclude that dual immunoreactivity for bcl-2 and mcl-1 is a feature of malignant neoplasms with thymic differentiation in general, both within the thymus and at ectopic sites.

Association of a polymorphism of the transforming growth factor-beta1 gene with genetic susceptibility to osteoporosis in postmenopausal Japanese women

Transforming growth factor-beta (TGF-beta) is both abundant in bone and an important regulator of bone metabolism. A T-->C transition at nucleotide 29 in the signal sequence region of the TGF-beta1 gene results in a Leu-->Pro substitution at amino acid position 10. The possible association of this polymorphism with bone mass and the prevalence of osteoporosis has now been investigated in a total of 287 postmenopausal women from two regions (Obu City, Aichi Prefecture, and Sanda City, Hyogo Prefecture) of Japan. A significant association of TGF-beta1 genotype with bone mass was detected in both populations; bone mineral density (BMD) at the lumbar spine was greater in individuals with the CC genotype than in those with the TT or TC genotype. The frequency of vertebral fractures was significantly lower in individuals with the CC genotype than in those with the TC or TT genotypes. For each region, multivariable logistic regression analysis revealed that the frequency of the T allele was significantly higher in subjects with osteoporosis than in controls. Also, the serum concentration of TGF-beta1 in individuals with the CC genotype was significantly higher than that in age-matched subjects with the TC or TT genotype in osteoporotic or osteopenic as well as healthy control groups. These results suggest that the T/C polymorphism of the TGF-beta1 gene is one of the genetic determinants of bone mass and that the T allele is an independent risk factor for the genetic susceptibility to osteoporosis in postmenopausal Japanese women. Thus, analysis of the TGF-beta1 genotype may be useful in the prevention and management of osteoporosis.

Detection of a novel nonsense mutation of the MEN1 gene in a familial multiple endocrine neoplasia type 1 patient and its screening in the family members

We identified a novel nonsense mutation(R29X) of the MEN1 gene in a familial multiple endocrine neoplasia type 1 (MEN1) patient. Molecular analysis of the MEN1 gene was performed in the family members by a restriction digestion method. The same mutation pattern was seen in both the proband's younger brother and cousin diagnosed as MEN1, and was also observed in the son of the cousin who showed signs of normal levels of serum PTH associated with mild hypercalcemia and hypophosphatemia. These findings suggest that mutation analysis of the MEN1 gene is very useful in identifying the subclinical state of MEN1 as well as clinical MEN1.

Restricted expression of oncofetal fibronectin mRNA in thyroid papillary and anaplastic carcinoma: an in situ hybridization study

Restricted expression of oncofetal fibronectin mRNA in the tissues of thyroid papillary and anaplastic carcinoma has recently been shown by both Northern blot analysis and reverse transcriptase polymerase chain reaction (RT-PCR). Oncofetal fibronectin mRNA can be a target of gene diagnosis and targeted gene therapy, provided it is expressed in all cancer cells in the tissues. To investigate this criterion in thyroid cancer tissues, we measured their expression of oncofetal fibronectin mRNA using in situ hybridization. An abundant expression of oncofetal fibronectin mRNA was found in all the observed cancer cells of six papillary carcinomas and an anaplastic carcinoma, but not in the tissues of normal thyroid, Graves' disease, adenomatous goitre, follicular adenoma, follicular carcinoma or medullary carcinoma. This result encourages us to establish gene diagnosis of thyroid papillary and anaplastic carcinomas by detecting oncofetal fibronectin mRNA in biopsies.

Mutational analysis of the RET proto-oncogene in 71 Japanese patients with medullary thyroid carcinoma

Multiple endocrine neoplasia types 2A and 2B (MEN2A and MEN2B) and familial medullary thyroid carcinomas (FMTC) are caused by germline mutations in the RET proto-oncogene. To investigate the spectrum of RET mutations among Japanese patients, we screened the RET gene in 71 patients with thyroid carcinomas. The panel included representatives of 44 families carrying FMTC or MEN2, 22 sporadic medullary thyroid carcinomas (MTCs), and five MTCs without familial information. Mutations in nucleotide sequences encoding one of three specific cysteine residues in the extracellular domain of the RET protein were found in 33 of the 34 MEN2A patients and in five of the six FMTC patients examined. A mutation at codon 918, causing the substitution of threonine for methionine in the tyrosine kinase domain of the protein, was found in germline DNAs of all four patients with MEN2B and in two of the 22 patients with sporadic MTCs; codon 918 was mutated somatically in tumor DNAs from three other sporadic cases. Germline mutations of codon 768, GAG to GAC (Glu to Asp), were detected in one FMTC, in one patient with sporadic MTC, and in one of the patients without familial information. Two somatic mutations, an Asp to Gly substitution at codon 631 and a Cys to Arg substitution at codon 634, had not been reported previously. Of five germline mutations found among the 22 sporadic cases, four were confirmed as de novo mutations since in each case neither parent carried the mutation. As nearly one-fourth of the patients with sporadic MTCs carried germline mutations and 50% of their children are expected to develop MTC and other endocrine tumors, these results indicated the importance of careful clinical surveillance of family members of any patient with MTC.

Gene rearrangement of immunoglobulin as a marker of thyroid lymphoma

Thyroid lymphoma occurs most commonly in the thyroid gland in association with Hashimoto's thyroiditis. Histologic findings occasionally cannot distinguish lymphoma from Hashimoto's thyroiditis, which creates a serious problem of whether treatment should be initiated. For this study, we examined 33 lymphoma tissues and 10 thyroid tissues from patients with Hashimoto's thyroiditis for the presence of gene rearrangement of immunoglobulin, which represents clonality of B-cell-derived tumors. Genomic DNA from thyroid tissues was digested with Bam H1 and Hind III restriction enzymes followed by electrophoresis. A Southern blot was performed with an IgH-JH probe or IgL-J kappa probe to detect gene rearrangement. Of the 33 lymphoma tissues, 27 (85%) showed gene rearrangement of immunoglobulin, whereas none of Hashimoto's thyroiditis tissue showed gene rearrangement. Five patients with a positive histologic diagnosis of lymphoma showed a negative gene rearrangement and were treated as having lymphoma. We encountered one case of lymphoma (plasmacytoma) in which gene rearrangement (not histologic findings) was diagnostic. Gene rearrangement of immunoglobulin can be used to detect thyroid lymphoma, particularly when the histologic diagnosis is inconclusive. The sensitivity of detecting thyroid lymphoma by the Southern blot method was about 85% in the present series.

Intrathyroidal epithelial thymoma (ITET)/carcinoma showing thymus-like differentiation (CASTLE) exhibits CD5 immunoreactivity: new evidence for thymic differentiation

AIMS

Cases of intrathyroidal epithelial thymoma (ITET)/carcinoma showing thymus-like differentiation (CASTLE) were examined for CD5 immunoreactivity, a feature of true thymic carcinoma, but not other thymic epithelial neoplasms or carcinomas of other sites. ITET/CASTLE, a rare, low-grade malignant neoplasm arising within the thyroid gland which resembles lymphoepithelioma-like and squamous cell carcinoma of the thymus, is postulated to arise from remnants of branchial pouch capable of thymic differentiation, but thymic differentiation in this neoplasm remains unproven.

METHODS AND RESULTS

The largest published series of cases of ITET/CASTLE was examined for CD5 immunoreactivity using an anti-CD5 antibody reactive in fixed, paraffin-embedded tissue with microwave antigen retrieval. Neoplastic cells in all five cases of ITET/CASTLE studied were immunoreactive for CD5, including foci of tumour metastatic to lymph node and lung. In contrast, none of five cases of thyroid carcinoma with squamous differentiation was immunoreactive for CD5. A minority of cases of typical thyroid carcinomas showed some weak immunoreactivity for CD5. Other carcinomas of the head and neck were nonimmunoreactive for CD5.

CONCLUSIONS

CD5 immunoreactivity in ITET/CASTLE is new evidence in support of thymic differentiation in this neoplasm.

Iodine-131 MIBG imaging in multiple endocrine neoplasia type 2B

A 16-year-old boy had a swollen neck that was a result of multiple endocrine neoplasia Type 2B (MEN 2B). CT revealed bilateral thyroid tumors, swelling of right cervical lymph nodes, and slight enlargement of the right adrenal gland. I-131 metaiodobenzylguanidine (MIBG) scintigraphy demonstrated increased uptake in the right adrenal gland and the left thyroid tumor, but no abnormal uptake in the right thyroid tumor and the right cervical lymph nodes. Postoperative pathologic findings were consistent with the diagnosis of right adrenal medullary hyperplasia, which is a precursor of pheochromocytoma. In patients with MEN 2B, I-131 MIBG scintigraphy in conjunction with CT of the adrenal glands should be performed to determine the disease stage of the adrenal medullae. In the cervical region, the diagnosis was medullary thyroid carcinoma (MTC) in both thyroid tumors and metastases in the right cervical lymph nodes. The right MTC was more aggressive than the left MTC. It is interesting that not all sites of known MTC take up I-131 MIBG to the same degree.

Carcinoma of the colon in childhood; report of 2 cases expressing p53 without K-ras mutation

We report on 2 children with colonic carcinoma and also review 62 cases of Japanese children with colonic carcinoma including ours. Although the dismal prognosis in colonic cancer in children is possibly due to the predominance of poorly differentiated carcinoma, there is no significant difference in the 5-year survival rates among well, moderately and poorly differentiated carcinomas in children. Positive staining with p53 in tumor cells was observed in each, but K-ras mutations were not detected in any. Therefore, these carcinomas possibly developed from de-novo carcinoma. The development pathway of colonic carcinoma may relate to the prognosis in children, and be different from that in adults.

A novel somatic mutation in the RET proto-oncogene in familial medullary thyroid carcinoma with a germline codon 768 mutation

In individuals who carry germline mutations in tumor suppressor genes predisposing them to inherited cancer syndromes, occurrence of somatic mutations in the same genes contributes to tumorigenesis. Germline mutations in the RET proto-oncogene predispose individuals to multiple endocrine neoplasia (MEN) type 2 syndromes. Since these mutations are oncogenic by themselves, somatic mutations in the same gene had been thought unnecessary. Recently, a somatic mutation at codon 918 of RET was reported in medullary thyroid carcinoma (MTC) and C-cell hyperplasia in patients with MEN 2A or familial MTC (FMTC), suggesting its possible contribution to tumorigenesis. We describe here a novel somatic mutation at codon 919 in a patient with FMTC carrying a germline mutation at codon 768 that may also be related to tumor progression.