Biomedical subjects

S Guyétant

Publications and source records attributed to S Guyétant.

10 recordsLinked to original sources

PubMed2006

C-cell hyperplasia.

Routine calcitonin assay programs and recent studies on the natural history of familial medullary thyroid carcinoma (MTC) have greatly added to our understanding of C-cell hyperplasia (CCH) and refined its classification. This article is an update on CCH physiopathology related to clinical presentation. With this combined approach, two types of CCH that differ by their physiological characteristics can be identified: neoplastic CCH and reactive (also called physiological) CCH. Neoplastic CCH is caused by a germline mutation of the RET protooncogene in a multiple endocrine neoplasia type 2 (MEN 2) syndrome. It progresses to MTC following a time line that depends on the RET mutation involved. CCH may actually be a misnomer for a neoplastic condition that some authors have proposed to call "in situ-MTC". Reactive CCH is considered to be caused by a stimulus that is external to the C-cell, and its premalignant potential is not documented. Many situations such as hypercalcemia, hyperparathyroidy, chronic lymphocytic thyroiditis or follicular tumors have been associated with reactive CCH, the pathogenesis of which remains unclear. But C-cell density in normal patients is subject to important variability, and several studies have demonstrated the dramatic male predominance in physiological CCH when hypercalcitoninemia was a random discovery. These data suggest that a number of conditions which were previously associated with reactive CCH might be purely fortuitous. Our clinical/pathological confrontation contributes to appropriately distinguishing between various CCH types, and in turn to identify the best way of managing patients.

Animals↗

PubMed2005

Expression and methylation status of tissue factor pathway inhibitor-2 gene in non-small-cell lung cancer.

Tissue factor pathway inhibitor-2 (TFPI-2) is a Kunitz-type serine proteinase inhibitor that inhibits plasmin-dependent activation of several metalloproteinases. Downregulation of TFPI-2 could thus enhance the invasive potential of neoplastic cells in several cancers, including lung cancer. In this study, TFPI-2 mRNA was measured using a real-time PCR method in tumours of 59 patients with non-small-cell lung cancer (NSCLC). Tumour TFPI-2 mRNA levels appeared well correlated with protein expression evaluated by immunohistochemistry and were 4-120 times lower compared to those of nonaffected lung tissue in 22 cases (37%). Hypermethylation of the TFPI-2 gene promoter was demonstrated by restriction enzyme-polymerase chain reaction in 12 of 40 cases of NSCLC (30%), including nine of 17 for whom tumour TFPI-2 gene expression was lower than in noncancerous tissue. In contrast, this epigenetic modification was shown in only three of 23 tumours in which no decrease in TFPI-2 synthesis was found (P=0.016). Decreased TFPI-2 gene expression and hypermethylation were more frequently associated with stages III or IV NSCLC (eight out of 10, P=0.02) and the TFPI-2 gene promoter was more frequently hypermethylated in patients with lymph node metastases (eight out of 16, P=0.02). These results suggest that silencing of the TFPI-2 gene by hypermethylation might contribute to tumour progression in NSCLC.

Adult↗

PubMed1999

Medullary thyroid microcarcinoma: a clinicopathologic retrospective study of 38 patients with no prior familial disease.

Thirty-eight patients (25 women, 13 men; mean age, 57.8 [32 to 91]) showing one or more medullary thyroid microcarcinomas (ie, < 1 cm), with no prior MEN II or medullary thyroid carcinoma history in their family, were reviewed. Follow-up was available for 29 patients (mean, 53.6 months [1 to 147]). 21 patients (72.4%) are alive and free of disease, four patients (13.8%) died during follow-up without disease, 2 patients are alive with disease (local recurrence and persistent hypercalcitoninemia) after 80 and 99 months, respectively, and 2 patients died of disease after 24 and 46 months. Most tumors were incidental pathological findings (19 of 38) or were discovered by systematic blood calcitonin measurement for a nodular thyroid disease (15 of 38). Only the four patients who had an unfavorable outcome were symptomatic cases (palpable micro-MTC, diarrhea, cervical lymph node metastasis and pulmonary metastatic disease). The two patients with metastatic disease at diagnosis died during follow-up. In univariate analysis, a symptomatic medullary thyroid carcinoma was a strong predictor of an unfavourable outcome (p < .00008), as were the preoperative calcitonin level (P = .007) and an elevated postoperative calcitonin level (P = .004). Among 30 histopathological criteria, only the presence of amyloid correlated with an unfavorable outcome (P = .018).

Adult↗

PubMed1998

[Prognostic value of Fürhman's grade in renal cell carcinoma. A study of 170 cases].

In order to evaluate the prognostic value of the anatomical stage (pTNM 1992) and of the histological factors (Führman's grade, cellular and architectural types), 170 renal cell carcinoma diagnosed between 1971 and 1991 were reviewed. In univariate analysis, the prognosis was correlated with the anatomical stage and Führman's grade: for the 125 patients without metastasis, grades 1 and 2 had a good prognosis, whereas grades 3 and 4 did poorly. The cellular type was not related to survival. Among architectural types, only the pseudo-sarcomatous type was correlated with prognosis. Multivariate analysis revealed that grade and metastasis at diagnosis were two independent predictors of survival; the grade was prognostically superior to metastasis. Führman's grade is essential in determining prognosis; its statistical value is superior to anatomical stage in multivariate analysis.

Adult↗

PubMed1998

[Frozen section examination in thyroid pathology. Technique and effective indications].

Frozen section examination for intraoperative diagnosis is often difficult in thyroid pathology. Fine-needle aspiration is widely used in the patients selection for surgery. Such a selection is accompanied by an increase in difficult frozen section cases, whose diagnosis is often differed to permanent sections. Thus, frozen section sensitivity is relatively low. In the era of cost containment, an increasing number of authors suggest that frozen section examination is unnecessary, and that surgical planning could rely on preoperative cytology only. Others consider fine-needle aspiration cytological evaluation and frozen section examination as complementary tools and recommend their association. The authors describe the technical aspects and difficulties of frozen section examination in thyroid pathology, and discuss its interest in surgical planning, in the light of preoperative cytology. Each team has to estimate local thyroid cytology development and accuracy, to define new indications for frozen section examination in thyroid pathology, according to local therapeutic choices. Such an approach could consistently reduce the number of intraoperative consultation for thyroid pathology, without prejudice for the patients.

Biopsy, Needle↗

PubMed1997

Sex-related C cell hyperplasia in the normal human thyroid: a quantitative autopsy study.

We report a prospective quantitative image analysis study of C cells in 57 normal autopsy thyroid glands, serially sectioned and wholly embedded in paraffin; all slides were immunohistochemically stained for calcitonin. Computerized quantitative image analysis was performed on 47 cases to measure C cell surface area and parenchymatous surface area after immunoperoxidase staining for calcitonin. The method was time-effective, with a good reproducibility. C cells were mainly found in the middle third of each lobe. Important inter-individual variations were observed; the maximum C cell surface area in a section (Amax) ranged from 28 x 10(3) to 470 x 10(3) microns2 (mean, 167 x 10(3) microns2) among 42 adults. Of particular interest was the important difference observed between sexes; Amax was twice as high in men (mean, 201 x 10(3) microns2) as in women (mean, 91 x 10(3) microns2; P = 0.0009). Moreover, 14 (33%) adult subjects [2 women (15%) and 12 men (41%)] fulfilled C cell hyperplasia criteria, i.e. at least 3 fields at x 100 magnification containing more than 50 C cells, suggesting that a substantial part of the normal adult population could have C cell hyperplasia.

Adult↗

PubMed1997

[Histopathology of neuroendocrine tumors].

Neuroendocrine (NE) tumors are a heterogeneous group of neoplasms arising in various organs and sharing the features of the NE cell system. The term "neuroendocrine" is used for cells characterized by their secretory products and some cytoplasmic proteins rather than by their localization and embryological derivation. Some tumor types can show a characteristic pattern on conventional histology but, to obtain an accurate diagnosis of many NE tumors it is necessary to employ various special methods, mainly electron microscopy and immuno-histochemistry. The classification of NE tumors in four categories according to Travis et al. is largely used: typical carcinoid and atypical carcinoid are low grade neoplasms; small cell NE carcinoma and large cell NE carcinoma are high grade neoplasms. The size, extension into surrounding tissues, angioinvasion and hormonal function are also important to consider in the prognostic evaluation of some NE tumors. Tumors exhibiting multidirectional differentiation must be classified in carcinoma with interspersed NE cells, carcinoid with interspersed non NE cells, composite tumors and amphricine tumors. Finally, some NE tumors may present features suggesting a Multiple Endocrine Neoplasia, ie. multifocality and association with hyperplasia of endocrine cells.

Humans↗

PubMed1996

Histopathology of bone marrow after allogeneic bone marrow transplantation for chronic myeloid leukaemia.

The histopathology of bone marrow after allogeneic bone marrow transplantation for chronic myeloid leukaemia (CML) was studied in 20 bone marrow biopsy specimens from 14 patients. Biopsies were performed at day 30 post-transplantion (5 biopsies), between day 90 and day 100 (14 biopsies), and one year post-transplantation (1 biopsy). Eight biopsies taken at day 30 post-transplantation for lymphoproliferative disorder were studied as controls. Granulopoiesis was predominant in all day 30 bone marrows in patients treated for CML. In 2 cases, rejection was suspected because of marrow hypoplasia at day 30: one case developed acute leukaemia soon after persistant hypoplasia at day 90 while the evolution of the other case was good. Two day 30 biopsies showed granulocytic hyperplasia but follow-up proved complete remission of CML. Thus, in our series, early biopsies at day 30 did not have any prognostic value. Twelve cases at day 90-100 showed little modifications, such as minor dyserythropoiesis and dysmegakaryopoiesis. One case showed granulocytic hyperplasia at day 100 but bone marrow was normal one year later and the patient in complete remission. The haematopoietic reconstitution after allogeneic bone marrow transplantation may present a transient granulocytic hyperplasia that must not be diagnosed as a persistence of CML.

Adult↗

PubMed1996

[Non-neoplastic hypercalcitoninemia. Pathological anatomy].

Normal C-cells are classically concentrated between the upper and middle thirds of each thyroid lobe and account for less than 1% of the thyroid gland volume. C-cell hyperplasia (CCH), defined as the presence of at least 3 low-power magnification (x100) microscopic fields containing more than 50 C-cells and at least 40 cells/cm2 was first described in a familial context of MEN2. It was then observed in many other conditions, especially in association with chronic lymphocytic thyroiditis or with thyroid tumors other than medullary thyroid carcinoma (MTC). In members of a MEN2 family, carrying a RET mutation, CCH is constant and associated with micro-MTC. At least 20% of patients with chronic lymphocytic thyroiditis or with a thyroid tumor other than MTC have CCH that, in a few cases, is associated with hypercalcitoninemia. 20 % normal subjects meet quantitative criteria of CCH. Patients belonging to a MEN2 family, without a RET mutation but presenting hypercalcitoninemia, could belong to this group. HCC appears to be a pre-neoplastic condition only in patients carrying a RET mutation. Under other circumstances, HCC may be either a reactive or even a normal condition.

Calcitonin↗

PubMed1995

[Hyperthyroidism induced by amiodarone and hyperthyroidism induced by iodine. Histologic, immunohistochemical and ultrastructural aspects].

Amiodarone is a widely-used anti-arythmic drug that induces an iodine overload and, in 1 to 23% of the patients, a thyrotoxicosis. In a few cases, the thyrotoxicosis may be refractory to conventional pharmacological therapy, thus leading to thyroidectomy. We report the thyroid gland pathology in 5 thyroidectomies that were performed for uncontrolled thyrotoxicosis, induced by amiodarone (4 cases) and by Colchimax, another iodine-rich drug (1 case). Two cases have been studied by electron microscopy. Pathologic findings were: [1] colloid transformation of the parenchyma, [2] areas of follicular disruption with numerous foamy macrophages in the colloid, [3] regenerative areas and [4] a moderate T lymphocytic infiltration. No lysosomal lamellar inclusion body was found by electron microscopy. These lesions may be rather specific of an iodine toxicity. The pathogeny is still misunderstood, and probably complex. It may essentially involve toxic mechanisms, as well as immunologic or allergic mechanisms.

Adult↗