Michel Peoc’h

Global DNA methylation evaluation: potential complementary marker in differential diagnosis of thyroid neoplasia

The implications of global DNA hypomethylation were recently reported in several models of tumorigenesis. Little is known about this epigenetic event in thyroid neoplasia. The study aimed to evaluate the status of global DNA methylation in several types of thyroid tumors using a monoclonal antibody specific for 5-methylcytidine (5-mc) and to define the diagnosis potential of this marker. 5-mc immunostaining scores were calculated in 17 papillary thyroid carcinomas (PTC), 6 follicular thyroid carcinomas (FTC), 16 follicular adenomas (FA), 19 nodular goiters (NG) and ten Hürthle cells adenomas (HCA). The expression of galectin-3 was also evaluated. Computerized image analysis showed a significant lower level of 5-mc immunostaining in thyroid carcinoma when compared with benign tumors or adjacent normal thyroid parenchyma (P<0.0001). Overall, 5-mc accuracy to distinguish malign from benign thyroid tumors was similar to that of galectin-3 (89% versus 87%, P>0.05). The combination of 5-mc with galectin-3 led to an excellent accuracy level of 96%. Among follicular neoplasia 5-mc accuracy to differentiate malign tumors trends to be higher than galectin-3 one (90% versus 66%, P=0.06). These data stress the necessity of epigenetic events evaluation among thyroid nodules and propose global DNA methylation assessment as a potential diagnostic tool to combine with other valuable markers.

Use of Poloxamers for Deswelling of Organ-Cultured Corneas

PURPOSE Dextran T500, routinely used as a deswelling supplement in organ culture (OC), has been suspected of being toxic to corneal endothelial cells (ECs). This study was conducted to evaluate the innovative use of poloxamers compared with dextran for deswelling OC corneas. METHODS Five poloxamers (P124, P188, P237, P338, and P407) were dissolved respectively in a standard OC medium to reach 350 mOsmol/kg. In vitro cytotoxicity of these media was tested by MTT assay on human corneal epithelial and endothelial cell lines and on primary human corneal fibroblasts. Paired human corneas stored in OC for at least 21 days were assigned for 48 hours to a poloxamer medium or to a standard deswelling medium containing 5% dextran T500. Corneal EC density, morphometry, visualization, mortality, stromal thickness, transparency, and folding were evaluated before and after deswelling. Corneas were finally cut into three parts for histologic and ultrastructural observation. RESULTS Besides similar corneal transparency improvement and thickness deswelling, poloxamers (except P124) reduced EC loss and facilitated endothelial visualization, but improved stromal folding less than dextran. The similar ultrastructures observed in the two groups were epithelial shedding, normal collagen fiber diameter and organization, uptake of deswelling agents by ECs, vacuolization but normal organelles in ECs and keratocytes, and endothelial surface modifications. CONCLUSIONS P188, P237, P338, and P407 performed similarly in preserving ECs, improving EC visualization, deswelling corneal stroma and inducing moderate injuries to corneal ultrastructure. They appear superior to dextran for corneal deswelling in OC.

Lamina propria of the human vocal fold: histomorphometric study of collagen fibers

BackgroundSince the seminal work of M. Hirano, which defined the three-layered lamina propria of the human vocal fold, there has been confusion in the labeling of each layer. Recent studies described the composition of fibers and interstitial molecules within the lamina propria leading to various biomechanical properties. However, collagen fibers appear as the most important structure component.MethodsWe used an optical analysis and the picrosirius-polarization method to describe collagen fibers from six adult and two fetal human larynges fixed in formalin and frontally sectioned in the middle part of the vocal fold.ResultsThe deep layer of the lamina propria is the most densely organized band of collagen fibers penetrating the superficial muscle bundles of the vocal muscle. The mean thickness of this layer is about 36% of the lamina propria and shows a network of strongly birefringent fibers (collagen type I and III). The superficial layer of the lamina propria is a narrow band of collagen fibers immediately below the basement membrane of the epithelium. The mean thickness of this layer is about 13% of the lamina propria and shows strong birefringent fibers. The intermediate layer is the less densely organized band between the deep and superficial layers. The mean thickness of this layer is about 51% of the lamina propria and shows clear, green weakly birefringent fibers characterized as collagen type III. The fetal lamina propria contains only a monolayer distribution of loose collagen fibers between the epithelium and the vocal muscle.ConclusionThese results help describe the distribution of collagen fibers within the lamina propria of the human vocal fold and have implications to understand the cover-body theory of voice production both in the adult and newborn.

Papillary thyroid microcarcinoma: incidence and prognostic factors

The objective of this study was to define the prognostic factors of papillary microcarcinoma of the thyroid (PMCT), and to analyse their epidemiologic and histopathologic characteristics. Our series included 57 patients diagnosed with PMCT between 1994 and 2003 among 944 patients who underwent thyroid surgery. All the surgical specimens were examined in the same department of pathology using the same technique. The prognostic factors were elaborated from the results of the histological examination. The epidemiological and histopathological characteristics were also evaluated. Two sub-groups were distinguished: patients with node disease and/or with metastasis (17 patients) and patients without node disease and metastasis (40 patients). The architecture of PMCT was papillary in 14% of cases, follicular in 35% of cases and mixed in 49% of cases, with no significant difference between any two groups. Histopathologic characteristics such as the vascular extension, infiltration into the adjacent parenchyma or in the thyroid capsule are all indicative of a poor prognosis. Two categories of PMCT, with and without the risk of metastatic spread, can be identified from these prognostic factors.

Differential expression of prognostic markers in histological subtypes of papillary renal cell carcinoma

To assess the expression of the tumour markers stromelysin 3, MUC1, p53 and cytokeratin‐7 in papillary renal cell carcinoma (pRCC, for which two histological subtypes are distinguished, i.e. type 1 and type 2, the latter appearing to be associated with a poorer prognosis) and to determine whether any of these markers might be of prognostic value.

3D map of the human corneal endothelial cell.

Corneal endothelial cells (CECs) are terminally differentiated cells, specialized in regulating corneal hydration and transparency. They are highly polarized flat cells that separate the cornea from the aqueous humor. Their apical surface, in contact with aqueous humor is hexagonal, whereas their basal surface is irregular. We characterized the structure of human CECs in 3D using confocal microscopy of immunostained whole corneas in which cells and their interrelationships remain intact. Hexagonality of the apical surface was maintained by the interaction between tight junctions and a submembraneous network of actomyosin, braced like a drum. Lateral membranes, which support enzymatic pumps, presented complex expansions resembling interdigitated foot processes at the basal surface. Using computer-aided design and drafting software, we obtained a first simplified 3D model of CECs. By comparing their expression with those in epithelial, stromal and trabecular corneal cells, we selected 9 structural or functional proteins for which 3D patterns were specific to CECs. This first 3D map aids our understanding of the morphologic and functional specificity of CECs and could be used as a reference for characterizing future cell therapy products destined to treat endothelial dysfunctions.

Epidural capillary hemangioma of the thoracic spine with proximal nerve root involvement and extraforaminal extension

Dear Editor, The occurrence of purely epidural capillary hemangioma is exceedingly rare, with only four reported cases in the English literature [3, 6, 7, 12]. Because of the excessive vascularity of capillary hemangioma, en bloc removal and/ or preoperative embolization of feeding arteries of the lesion should be recommended [8]. However, as consensus magnetic resonance imaging (MRI) study and specific features regarding capillary hemangiomas are not yet available, they are usually misdiagnosed preoperatively [3, 7]. Here, we report a case of a capillary hemangioma of the thoracic epidural region, with particular emphasis on relevant radiological features that could aid in the differential diagnosis of the lesion and therefore allow appropriate management. A 59-year-old woman presented with a 1-year history of back pain and right intercostal neuralgia. Physical examination revealed proprioceptive ataxia that caused difficulties with walking, decrease of the motor strength in lower limbs, and brisk osteotendinous reflexes. MRI (Fig. 1a–d) demonstrated a well-circumscribed, probably epidural, avidly enhancing mass that extended from T5 to T7, with intrathoracic extension through the right foramen at T6–T7, abutting the adjacent pleura. Signal void areas in and around the lesion indicated the presence of draining veins, suggesting the differential diagnosis of vascular pathologies such as hemangioma or hemangioblastoma. A T5–T7 laminectomy was performed with removal of the right T6–T7 facet joint and corresponding costotransverse joint to expose the whole lesion. The spongy, redpurple hemorrhagic epidural mass (Fig. 1e) was clearly originating from the T6 proximal nerve root, easily cleaved from the dura, and excised en bloc (Fig. 1f) as planned preoperatively. Many small feeder branches and vessels draining into the epidural venous system were sacrificed. The estimated intraoperative blood loss was 2 l. Pathologic examination showed innumerable thin-walled capillary vessels, lined by flattened endothelium and embedded within a loose connective tissue stroma (Fig. 1g) consistent with a capillary hemangioma. Unlike cavernous hemangiomas, the lesion was devoid of abnormally hyalinized vascular channels, thromboses, calcifications, or surrounding deposition of hemosiderin pigment. Capillary hemangiomas are considered hamartomatous proliferations of vascular endothelial cells [2]. They are classified by the predominant type of vascular channel (capillary, cavernous, arteriovenous, or venous) observed at histological examination. Epidural hemangiomas are actually considered to be an extension of vertebral lesions [4, 5]. The occurrence of purely spinal epidural hemangiomas is exceedingly rare, and most of the reported cases were a cavernous type [4, 5, 9]. However, as histological differentiation between capillary hemangioma and cavernous hemangioma is not always unequivocal, some epidural capillary hemangiomas may have been published under the designation of cavernous F. Vassal : C. Nuti Department of Neurosurgery, North Hospital, University Hospital of Saint-Etienne, Saint-Etienne, France

Ex vivo confocal microscopy imaging to identify tumor tissue on freshly removed brain sample.

Confocal microscopy is a technique able to realize “optic sections” of a tissue with increasing applications. We wondered if we could apply an ex vivo confocal microscope designed for dermatological purpose in a routine use for the most frequent brain tumors. The aim of this work was to identify tumor tissue and its histopathological hallmarks, and to assess grading criteria used in neuropathological practice without tissue loss on freshly removed brain tissue. Seven infiltrating gliomas, nine meningiomas and three metastases of carcinomas were included. We compared imaging results obtained with the confocal microscope to frozen sections, smears and tissue sections of formalin-fixed tissue. Our results show that ex vivo confocal microscopy imaging can be applied to brain tumors in order to quickly identify tumor tissue without tissue loss. It can differentiate tumors and can assess most of grading criteria. Confocal microscopy could represent a new tool to identify tumor tissue on freshly removed sample and could help in selecting areas for biobanking of tumor tissue.

Metastatic meningiomas: an unusual clinical and pathological diagnosis with highly variable outcome

Metastatic meningioma is a rare situation. We conducted a retrospective study from our databases and identified cases of metastatic meningioma. We report three presentations of patients with medical history of surgical removal of meningioma presenting several years later a liver tumor with bone metastasis or multiple lung tumors. These observations highlight the difficulty of the clinical and pathological diagnosis and the absence of consideration of metastatic state for histologically “benign” but clinically aggressive meningiomas in the current WHO 2007 classification of meningiomas. We also reviewed published cases of metastatic meningiomas since they are clearly distinguished from haemangiopericytoma.

Angiomyxome superficiel : à propos de quatre cas, dont deux lésions sous-unguéales

Resume Nous rapportons quatre observations d’angiomyxomes superficiels. Il s’agit de deux tumeurs cutanees et deux tumeurs sous-ungueales. L’analyse histologique a permis de faire le diagnostic d’angiomyxome superficiel qui est une entite d’individualisation assez recente. Il s’agit d’une tumeur myxoide paucicellulaire, lobulee, assez mal limitee, contenant d’assez nombreux petits vaisseaux sanguins autour desquels se dispersent quelques elements inflammatoires, en particulier des polynucleaires neutrophiles. Ces tumeurs expriment generalement le CD34. Le diagnostic differentiel se discute avec un neurothecome myxoide, un neurofibrome myxoide et pour les localisations ungueales avec un fibromyxome acral superficiel.