In Silico Analysis Identification of a Novel Germ-Line VHL Mutation in a Patient of Malignant Pheochromocytoma.

OBJECTIVE: Von Hippel-Lindau (VHL) disease is an autosomal dominantly inherited tumor syndrome caused by a VHL gene mutation. Here we report a novel mutation of VHL in a patient diagnosed with malignant pheochromocytoma at the age of 17. METHODS: A 17-year-old female was referred for paroxysmal supraventricular tachycardia and anemia. She was diagnosed with a left adrenal pheochromocytoma based on biochemical and imaging studies. A left adrenalectomy was performed. Six months after surgery, metastatic lesions were suspected in the lung. The histopathologic findings of thoracoscopic lung biopsy specimens confirmed metastasis of the malignant pheochromocytoma. RESULTS: Genetic analysis of VHL showed a novel missense mutation at codon 194 (V194G) in exon 3. This mutation was inherited from the paternal allele, and a loss of heterozygosity was noted in 3 of the patient's distinct tumors. Two independent in silico analyses suggested that this amino acid substitution was pathogenic. CONCLUSION: We identified a novel missense mutation of VHL in a young patient with malignant pheochromocytoma.

Two rare TSH receptor amino acid substitutions in toxic thyroid adenomas.

Toxic adenoma and toxic multinodular goiter (TMNG) are common causes of hyperthyroidism in iodine-deficient regions, but they are relatively rare in iodine-sufficient regions, including Japan. Constitutive activating mutations of the thyroid stimulating hormone receptor (TSHR) gene and adenylate cyclase-stimulating G α protein (GNAS) gene are frequent in these thyrotoxic disorders. Here we report two cases of rare TSHR gene mutations in Japanese thyrotoxicosis patients. In Case 1, we observed multiple toxic nodules with thyrotoxicosis, and in Case 2, we detected a solitary toxic nodule in an 8-year-old girl. In both cases, ultrasonography showed thyroid nodules and scintigraphy revealed increased uptake. Total thyroidectomy was performed for Case 1 and a hemi-thyroidectomy was performed for Case 2. Genetic analysis of the resected tissues revealed an I568F mutation in Case 1 and a S281I mutation in the TSHR gene in Case 2. The I568F mutation was located in the second extracellular loop, and the S281I mutation was located in the N-terminal extracellular domain of the TSH receptor. In Case 1, the mutation was restricted to the largest nodule, and was not detected in other functioning nodules or non-nodule thyroid tissue. Bi-allelic expression of the TSHR gene was confirmed by reverse transcription-polymerase chain reaction in both tumors. Both the I568F and S281I mutations were studied previously in vitro, and were revealed to cause basal activation of the protein kinase A pathway. Case 1 represents the second reported case of an I568F mutation and Case 2 represents the third reported case of an S281I mutation.

Serum levels of IgG and IgG4 in Hashimoto thyroiditis.

Although IgG4-related disease is characterized by extensive infiltration of IgG4-positive plasma cells and lymphocytes of various organs, the details of this systemic disease are still unclear. We screened serum total IgG levels in the patients with Hashimoto thyroiditis (HT) to illustrate the prevalence of IgG4-related thyroiditis in HT. Twenty-four of 94 patients with HT (25.5%) had elevated serum IgG levels and their serum IgG4 was measured. Five of the 24 cases had more than 135 mg/dL of IgG4, which is the serum criterion of IgG4-related disease. One was a female patient who was initially treated as Graves' disease and rapidly developed a firm goiter and hypothyroidism. The biopsy of her thyroid gland revealed that follicular cells were atrophic with squamous metaplasia, replaced with fibrosis, which was compatible with the fibrous variant of HT. Immunohistochemical examination revealed diffuse infiltration of IgG4-positive plasma cells, and the serum IgG4 level was 179 mg/dL. The levels of IgG and IgG4 were positively correlated with the titers of anti-thyroglobulin antibody or anti-thyroid peroxidase antibody. In conclusion, at least a small portion of patients with HT with high titers of anti-thyroid antibodies may overlap the IgG4-related thyroiditis.

Primary hyperparathyroidism due to atypical vertically long cystic adenoma.

UNLABELLED: Parathyroid cystic adenomas are often misdiagnosed as thyroid cysts and routine preoperative diagnostic tools, such as ultrasonography (US) or 99m technetium-sestamibi (99mTc-MIBI) scans, cannot clearly distinguish between these entities. We present a 67-year-old hypercalcemic woman with a cervical cystic lesion who had negative sestamibi scan results. Her laboratory data indicated primary hyperparathyroidism (serum calcium concentration 14.0 mg/dl, phosphate concentration 2.3 mg/dl, and intact parathyroid hormone (PTH) concentration 239 pg/ml). The cervical US and computed tomography scans revealed a large and vertically long cystic mass (12×11×54 mm). A mass was located from the upper end of the left thyroid lobe to the submandibular region and was not clearly distinguishable from the thyroid. For preoperative definitive diagnosis, we carried out a parathyroid fine-needle aspiration (FNA) and PTH assay (PTH-FNA) of liquid aspirated from the cyst. The intact PTH-FNA concentration was 1.28×10(6) pg/ml, and the patient was diagnosed with primary hyperparathyroidism due to a cystic mass. She underwent a left upper parathyroidectomy and her serum calcium and intact PTH concentration immediately decreased to normal levels. This report describes the usefulness of PTH-FNA for localizing and differentiating an atypical functional parathyroid lesion from nonfunctional tissue in primary hyperparathyroidism. LEARNING POINTS: Cystic parathyroid lesions, even in the case of elevated PTH levels, can produce negative results in 99mTc-MIBI scans.Preoperative diagnosis of parathyroid cysts detectable on US is possible by parathyroid FNA and PTH assay (PTH-FNA) of liquid aspirated from the cyst, if malignancy is not suspected. PTH-FNA could be helpful in the differential diagnosis of an equivocal cervical tumor.

Novel tandem germline RET proto-oncogene mutations in a patient with multiple endocrine neoplasia type 2B: report of a case and a literature review of tandem RET mutations with in silico analysis.

BACKGROUND: Multiple endocrine neoplasia type 2B (MEN2B) is the rarest and most aggressive form of MEN2. MEN2B cases usually carry either an M918T or A883T mutation of the RET, but to date, there are 3 atypical MEN2B caused by tandem mutations. METHODS AND RESULTS: A 32-year-old woman with no family history of medullary thyroid carcinoma (MTC) presented with a neck tumor and multiple mucosal nodules. She was diagnosed with MEN2B. Genetic analyses of RET revealed that she had 2 mutations, Q781R and V804M. Subclone and genetic analyses revealed that Q781R was on the paternal allele and V804M was a de novo. In silico analysis of the tandem mutations showed a high prediction score. CONCLUSIONS: We describe a novel combination of tandem RET mutations (Q781R/V804M) in a MEN2B-like patient. In silico analysis showed a high prediction score, which was compatible with the clinical phenotype in the present case.

A novel GATA3 nonsense mutation in a newly diagnosed adult patient of hypoparathyroidism, deafness, and renal dysplasia (HDR) syndrome.

OBJECTIVE: Hypoparathyroidism, deafness, and renal dysplasia (HDR) syndrome is an autosomal dominant disorder caused by a GATA3 gene mutation. Here we report a novel mutation of GATA3 in a patient diagnosed with HDR syndrome at the age of 58 with extensive intracranial calcification. METHODS: A 58-year-old Japanese man showed severe hypocalcemia and marked calcification in the basal ganglia, cerebellum, deep white matter, and gray-white junction on computed tomography (CT). The serum intact parathyroid hormone level was relatively low against low serum calcium concentration. The patient had been diagnosed with bilateral sensorineural deafness in childhood and had a family history of hearing disorders. Imaging studies revealed no renal anomalies. The patient was diagnosed with HDR syndrome, and genetic testing was performed. RESULTS: Genetic analysis of GATA3 showed a novel nonsense mutation at codon 198 (S198X) in exon 3. The S198X mutation leads to a loss of two zinc finger deoxyribonucleic acid (DNA) binding domains and is considered to be responsible for HDR syndrome. CONCLUSION: We identified a novel nonsense mutation of GATA3 in an adult patient with HDR syndrome who showed extensive intracranial calcification.

Confirmatory testing in primary aldosteronism.

CONTEXT: Although confirmatory testing to verify aldosterone excess is a key step in the diagnosis of primary aldosteronism (PA), there is no consensus as to whether it is always needed and which of the tests need to be performed. OBJECTIVE: The objective of this study was to investigate the diagnostic significance of confirmatory tests in PA. DESIGN AND PATIENTS: In group A, 120 hypertensive patients who had positive case detection using the aldosterone to renin ratio (ARR) were subjected to at least one confirmatory test: the captopril challenge test (CCT), furosemide upright test (FUT), or saline infusion test (SIT). Among group A, 57 patients underwent all three confirmatory tests (group B), and 57 patients were differentiated as having either unilateral or bilateral PA based upon adrenal venous sampling, adrenal scintigraphy, and/or adrenal surgery (group C). RESULTS: The percentages of patients with positive CCT and FUT were 86 and 87% in group A, 88 and 88% in group B, and 96 and 94% in group C, respectively. The percentage of patients with positive SIT results was lower than that with other tests (P < 0.01). The percentage of patients with positive results for the three tests was higher in patients with baseline ARR of at least 1000 or plasma aldosterone concentration (PAC) of at least 250 pg/ml than in those with lower ARR or PAC in all three groups. CONCLUSIONS: Most patients with positive case detection also had positive results on the CCT and FUT, especially when ARR was at least 1000 or PAC was at least 250 pg/ml under renin suppresion. Confirmatory testing for PA may not be needed in all patients with positive case detection.

R27X nonsense mutation of the SDHB gene in a patient with sporadic malignant paraganglioma.

It has been estimated that approximately 10% of pheochromocytomas and paragangliomas are part of a hereditary syndrome. Recent studies, however, suggest that the genetic involvement in pheochromocytoma/paraganglioma is actually far more common. Here, we report a case of malignant paraganglioma with no apparent family history. A 59-year-old man was referred to our services because of multiple abdominal masses. Plasma and urine adrenalin and noradrenalin levels were slightly elevated, and plasma dopamine and urine vanillylmandelic acid levels were remarkably elevated. Abdominal and chest computed tomography revealed multiple masses in the para-aortic region and in both lungs. Although (131)I-meta iodobenzylguanidine scintigraphy did not show significant uptake in these tumors, a 6-[(18)F]fluorodeoxyglucose positron emission tomographic scanning study showed multiple areas of uptake corresponding to the tumors. Biopsy of the tumors revealed paraganglioma with chromogranin A-immunopositive cells. Genetic analysis indicated a nonsense mutation at codon 27 of the SDHB gene. As recently described, SDHB mutations may cause extra-adrenal and malignant paragangliomas, such as in the present case.