[Biology of primary hyperparathyroidism: selective venous sampling]. / Biologie de l'hyperparathyroïdie primaire: prélèvements veineux étagés.

The diagnosis of primary hyperparathyroidism (PHP) is chemical: high level of Parathormone (PTH) in conjunction with hypercalcaemia. In borderline cases with sub-normal plasma PTH and calcium, an oral calcium load test could allow a differential diagnosis from other causes of high PTH. Imaging is required only for PHP. Selective venous sampling can help in localizing a parathyroid adenoma in difficult cases by PTH cartography in the following situations: imaging in favour of an ectopic mediastinal gland or a deep cervical adenoma, persistent or recurrent PHP after first failed surgery with negative neck exploration or unsatisfactory in case of another hypersecreting gland, PHP well diagnosed with indeterminate imaging, symptomatic PHP with normal PTH and negative imaging. Venous blood sampling performed in a vascular radiological department with a quick PTH assay can reveal an area of maximum secretion potentially linked to a nodule localized by previous ultrasound coupled to scintigraphy, giving thus a "biological imaging" study. The association of imaging and biology is an efficient procedure enabling localization of an area of abnormal PTH secretion and characterization of the level of PTH secretion. The area with the highest gradient of PTH concentration can help to protocol CT and MR examination.

Indications and limits of ultrasound-guided cytology in the management of nonpalpable thyroid nodules.

Although ultrasound (US)-guided fine needle aspiration biopsy (FNAB) is widely prescribed in nonpalpable thyroid nodules, the goal of this study was to define precisely the indications and limits of US-FNAB in a series of 450 nonpalpable nodules. Among 94 surgically controlled cases, 20 (8 infracentimetric and 12 centimetric or supracentimetric) carcinomas were diagnosed. The diagnosis of malignancy was successfully made by US-FNAB in 16 of 20 carcinomas, 3 were missed because of insufficient cytological material, and 1 was misdiagnosed. US-FNAB sensitivity and specificity were 94% and 63%, respectively. A logistic model indicated that nodule size (P < 0.6) was not associated with histological diagnosis, but that solid hypoechoic features were more likely to be malignant (P < 0.0003), with US sensitivity and specificity for malignancy of 80% and 70%, respectively. Logistic regression indicated that adequate cytological material significantly increased with nodule size (P < 0.0001). This result outlined the limits of US-FNAB in small nodules. Hence, indication of US-FNAB appears judicious in centimetric or supracentimetric nodules or in solid and hypoechoic ones. Such a management would allow the discovery of 15 of 20 carcinomas and would avoid 16% of unnecessary biopsies.

[Management of 29 children with thyroid cancer following the Chernobyl accident]. / Prise en charge de 29 enfants atteints de cancer de la thyroïde à la suite de l'accident de Tchernobyl.

As a consequence of the Chernobyl nuclear power plant accident, a considerable increase of thyroid cancer among contaminated children has been reported in Ukraine, Belarus and Russia. A group of 29 children aged from 5 months to 10 years (mean 4.7 years) at the time of the accident, with a papillary thyroid cancer, have been examined at the Pitié-Salpêtrière hospital in Paris. The cancer was discovered by systematic ultrasonography in only 25% of cases. No reliable dosimetric estimation was achieved. The initial surgical treatment was performed in Ukraine. Cervical lymph node and pulmonary metastases were present in 24 and 11 cases respectively. A complementary surgical treatment was necessary for 9 children and one to four radioiodine treatments were given to 24 children. With a mean delay of 7 years after the cancer discovery, an apparent cure or a remission was obtained for 20 children, 6 children have cervical lymph node metastases requiring a surgical treatment and 3 have evolving lung metastases. The management of the great number of foreseeable cases of thyroid cancer requires an improved systematic screening, a large number of rooms dedicated to high activity radioiodine treatments, funds for disposable material and training missions.

[Echography of thyroid nodules. The echography specialist facing the clinician's requirements]. / Echographie des nodules thyroïdiens. L'échographiste face aux exigences du clinicien.

The risk of malignancy in cases of unique non-functional thyroid nodules ranges from 5 to 20% and since definitive diagnosis can only be provided by the pathology examination, surgical removal could be planned in all cases. The clinician however also has the objective of proposing surgery to as few patients with benign nodules as possible and thus calls upon the echographist to help distinguish between malignant and benign nodules. Thus orders for echography carry an intrinsic request for diagnostic arguments, a precise analysis of the characteristics of the nodule and a description of possible multinodular dystrophy as well as an estimation of the probability of malignancy. The echographist's report must include a precise description of each thyroid lobe, the localization of the nodule, its size, contour, echostructure, echogenicity and calcifications. The cervical lymph node chains must also be explored. An analysis of the surrounding parenchyma can frequently confirm multinodular dystrophy. The size of the nodule is the determining factor in predicting malignancy. While for very small nodules, less than 1 cm in diameter, the malignant nature cannot be reasonably predicted, and inversely for very large nodules, invading an entire lobe, it is usually evident, for intermediate sized nodules, echography is a strategic diagnostic tool. No sign is pathognomonic but an association of arguments can favour malignancy: an unique isolated nodule, irregular contours, lymph node enlargement greater than 1 cm. Hypoechogenicity is another important characteristic with a positive predictive value of 50% to 63%. Overall, the sensitivity of echography is good at 75% with specificity of 61 to 83%.(ABSTRACT TRUNCATED AT 250 WORDS)