Searching for RET/PTC rearrangements and BRAF V599E mutation in thyroid aspirates might contribute to establish a preoperative diagnosis of papillary thyroid carcinoma

OBJECTIVE

Searching for multiple molecular markers in thyroid aspirates appears to be a promising approach for establishing a preoperative diagnosis of papillary thyroid carcinoma (PTC).

METHODS

Based on this hypothesis, a total of 63 samples from 55 patients, were collected at random. RNA was extracted from the residue cells inside the needle used for fine needle aspiration cytology (FNAC) and thereafter molecular analysis was carried out both for RETrearrangements (type 1, 2, 3) and BRAF codon 599 mutation molecule. Results were compared with the cytological and histopathological diagnoses in 24 patients submitted to surgery.

RESULTS

58% PTCs presented a genetic alteration either RET/PTC rearrangement, BRAF V599E mutation or both: three cases of PTCs (25%) presented a RET/PTC rearrangement; three cases of PTCs (25%) presented a BRAF V599E mutation and in one case (8%) both alterations were identified.

CONCLUSIONS

The present results suggest that searching for multiple molecular markers in thyroid aspirates may enhance the accuracy of FNAC and refine preoperative diagnosis of PTC.

MEN 2A families: from hot spots to hot regions

The aim of this study was to look for common ancestors among MEN 2A Portuguese families presenting with the same germ-line mutation of the RET proto-oncogene. To address this question from a genetic point of view, we performed haplotype analysis in six out of nine, apparently separate, MEN 2A families using four polymorphic markers. Three families carrying the C634R mutation and presenting the same phenotype shared the same haplotype surrounding the MEN 2A mutation. Moreover, these families were originally from the same geographic region although settled at different places along the country. Altogether, data suggested a common ancestral MEN 2A chromosome for three families. Since MEN 2A is a rare inherited cancer syndrome, identification of common ancestors may draw attention for specific geographic regions from where other affected families may arise at a higher chance and, therefore, termed 'hot regions'.

Medullary carcinomas of the thyroid: a monoclonal origin

We studied the clonality of medullary thyroid carcinomas (MTC) from 16 female patients by determining X chromosome inactivation by polymerase chain reaction (PCR) amplification of a CAG repeat in exon 1 of the human androgen-receptor gene. One patient with sporadic medullary thyroid carcinoma (MTC) was homozygous for this microsatellite and was not considered for the assessment of clonality. Sixteen tumor samples from the informative 15 patients were studied: 11 were from sporadic cases and 5 were from familial cases (3 cases of multiple endocrine neoplasia type 2A [MEN 2A]; 1 case of familial medullary thyroid carcinoma [FMTC]). Fourteen tumor samples (10/11 sporadic, 3/4 MEN 2A and 1/1 FMTC) were clearly monoclonal with allelic cleavage ratios between 2.5 and 49.1. Sixty-four percent of these cases (9/14) had the preferential amplification of the shorter allele while 36 percent (5/14) had the preferential amplification of the longer allele. Two frozen tumor samples (1 sporadic and 1 MEN 2A) were polyclonal. However, the corresponding tumor embedded in paraffin from the sporadic case was monoclonal. The other polyclonal tumor was found in the right thyroid lobe of a patient with MEN 2A who had a monoclonal tumor in the left lobe. Our results clearly demonstrate that MTC have a monoclonal origin in the majority of the cases.

Detection of thyroglobulin mRNA transcripts in peripheral blood of individuals with and without thyroid glands: evidence for thyroglobulin expression by blood cells

OBJECTIVE

Recent studies have assigned clinical significance and prognostic value to the detection of thyroglobulin (Tg) mRNA in the blood of patients subjected to total thyroidectomy for a papillary or follicular thyroid carcinoma. In this study, we investigated the diagnostic specificity of Tg mRNA detection, analysing blood samples from healthy volunteers and from patients previously subjected to total thyroidectomy for reasons other than a carcinoma of the follicular epithelium.

DESIGN AND METHODS

Total RNA was extracted from whole blood, reverse-transcribed and the cDNA amplified for Tg and glyceraldehyde-3-phosphate dehydrogenase with specific primers. Expression levels were analysed by using a semi-quantitative PCR. In a few cases, Lymphoprep gradients were used to separate the mononuclear and polymorphonuclear cells prior to further analysis by reverse transcription/PCR.

RESULTS

Our data suggested that all individuals expressed Tg mRNA. Moreover, no differences in the expression levels between subjects with and without thyroid glands were documented. Documentation of Tg expression by the mononuclear and polymorphonuclear layers in patients without thyroid glands support the hypothesis that both lymphocytes and granulocytes express Tg and may justify a background expression in blood, independently of the presence of follicular cells in circulation.

CONCLUSIONS

Tg mRNA expression is not limited to follicular cells of the thyroid gland, and its expression by normal blood cells should be considered in tests performed for diagnostic purposes.

Hypoglycaemia due to insulin autoimmune syndrome: report of two cases with characterisation of HLA alleles and insulin autoantibodies

OBJECTIVE

Insulin autoimmune syndrome (IAS) has been reported mainly in Japan and so far only 27 IAS cases have been described from outside Asia. We describe two unrelated Portuguese patients with IAS and characterise their insulin autoantibodies and HLA alleles.

PATIENTS

Patient 1, a 24-year-old white female suffered an episode of unconsciousness in the late postprandial state and blood glucose was found to be 33 mg/dl with serum insulin levels of >3980 microIU/ml (normal range 0-30 microIU/ml). She was receiving monthly injections of penicillin G for the prophylaxis of recurrent tonsillitis. Patient 2, was a 19-year-old white female, with episodes of sweating, hand tremor, weakness and hunger occurring in the postprandial state and blood glucose levels during the attacks of 28-56 mg/dl. Very high insulin levels (602-708 microIU/ml) were present.

METHODS AND RESULTS

Anti-insulin antibodies, determined by a semi-quantitative method, were strongly positive in both patients (91.7% in patient 1 and 88.6% in patient 2; normal range < or =7%). Sephadex G-100 chromatography of the sera showed most of insulin immunoreactivity present in the void volume which was retained by an affinity column with anti-human-immunoglobulin G antibodies (87% and 95% from patients 1 and 2 respectively). Scatchard plot analysis and molecular typing of the DRB1 gene revealed a polyclonal antibody and DRB1*0406 in patient 1, and a monoclonal antibody and DRB1*0403 in patient 2.

CONCLUSIONS

These two Portuguese patients with IAS had different HLA-DR4 subtypes and insulin autoantibodies: DRB1*0406 and a polyclonal antibody in a patient treated with penicillin, and DRB1*0403 and a monoclonal antibody in a patient with "idiopathic" IAS.

Bone mineral density and androgen levels in elderly males

To clarify the relationship of sex male hormones and bone in men, we studied in 140 healthy elderly men (aged 55-90 years) the relation between serum levels of androgens and related sex hormones, bone mineral density (BMD) at different sites, and other parameters related to bone metabolism. Our results show a slight decrease of serum-free testosterone with age, with an increase of follicle stimulating hormone (FSH) and luteinizing hormone (LH) in a third of the elderly subjects studied. BMD decreased significantly with age in all regions studied, except in the lumbar spine. We found a positive correlation between body mass index (BMI) and BMD at the lumbar spine and femoral neck (P < 0.001). No relationship was found (uni- and multivariate regression analysis) between serum androgens or sex hormone-binding globulin (SHBG) and BMD. We found a positive correlation of vitamin D binding protein (DBP) and osteocalcin with lumbar spine BMD and with BMI, DBP, IGF-1, and PTH with femoral neck BMD. In conclusion, there is a slight decline in free testosterone and BMD in the healthy elderly males. However, sex male hormones are not correlated to the decrease in hip BMD. Other age-related factors must be associated with bone loss in elderly males.

Molecular analysis of the RET proto-oncogene in patients with sporadic medullary thyroid carcinoma: a novel point mutation in the extracellular cysteine-rich domain

Germline point mutations in the RET proto-oncogene are associated with multiple endocrine neoplasia type 2 (2A and 2B) and familial medullary thyroid carcinoma. On the other hand, somatic point mutations of RET have been described in a subset of sporadic medullary thyroid carcinomas (MTCs). We examined tumor and blood DNA of thirteen apparently sporadic MTC patients for mutations in RET exons 10, 11, 13, 15 and 16 to determine whether they had true sporadic tumors or either de novo or occult germline mutations. Three different somatic missense mutations were documented in seven patients. In five patients a mutation in exon 16, codon 918, (ATG-->ACG) causing a Met-->Thr substitution was found. In the remaining two patients the mutation affected exon 11: codon 630 in one case and codon 634 in the other. In both cases a T-->C transversion was identified causing a Cys-->Arg substitution. In conclusion, absence of a germline mutation in RET exons 10, 11, 13 or 16 is evidence against an inherited form in all cases. In seven patients, identification of a somatic mutation supported the previous clinical diagnosis of sporadic medullary thyroid carcinoma; in one of them we identified a hitherto undescribed somatic point mutation at codon 630.

Difficulties in the management of a parathyroid carcinoma - case-report

The case of a parathyroid carcinoma in a 61-year-old woman is described. The patient was referred to our hospital, with the diagnosis of medullary thyroid carcinoma, after a prior thyroidectomy performed at another hospital. On admission, serum calcium was 3.92 mmol/l (n.r. 2.2-2.5), PTH level was 320 ng/l (n.r. 10-65), urinary cAMP was 508.9 mmol/mmol creatinine (n.r. 330- 630) and serum calcitonin was 2.1 ng/l (n.r.<10). The patient was then submitted to a complete neck exploration and multiple nodules were removed. Histopathological diagnosis of parathyroid carcinoma was made by local recurrence and retrospectively upon closer examination of the original specimen. After surgery, normocalcemia was achieved and maintained for about four months. Serum PTH decreased to 28.8 ng/l after surgery but increased quickly to 75.6 ng/l ten days later. Three months later, there was both biochemical and clinical evidence of disease. In the following eight months, calcium levels ranged from 2.99 mmol/l to 4-24 mmol/l and PTH from 135 ng/l to 1431 ng/l. However no distant metastases were found. To Control hypercalcemia, the patient was treated with bisphosphonates but normocalcemia was never achieved. A slight and transient reduction in serum calcium as response to an acute administration of octreotide, made us not to consider this eventual modality of therapy. Sonographically guided percutaneous injection of ethanol was performed but the treatment was not found to be effective. Finally, the use of chemotherapy with 5-fluorouracil, cyclophosphamide and dacarbazine was also unsuccessful. The patient died two years after the initial diagnosis.