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Resume Le reseau INCa RYTHMIC a pour but la prise en charge clinique de tout patient presentant une tumeur epitheliale thymique. Chaque patient atteint de cette tumeur doit pouvoir beneficier d’une RCP regionale ou nationale, basee sur le diagnostic du pathologiste initial. Toutefois, une relecture nationale est organisee au decours de la RCP pour chaque patient inclus dans le reseau clinique, relecture nationale qui doit etre distinguee du second avis demande de pathologiste a pathologiste pour une tumeur thymique difficile a classer. Cette revue a pour objectif de preciser aux pathologistes francais la methodologie de travail et l’experience acquise du groupe de relecture national qui a beneficie de l’excellente participation des pathologistes sur l’ensemble du territoire, lui permettant d’avoir relu plus de 1000 cas. Cette revue insiste sur l’importance de la prise en charge macroscopique pour faciliter une relecture adaptee, les principales caracteristiques histopathologiques et immunophenotypiques utilisees par le groupe pour faciliter la reproductibilite interobservateur de l’histotype, les diagnostics differentiels et les difficultes persistantes de la classification en stade.

Micronodular thymic carcinoma with lymphoid hyperplasia (MNTCLH) is a rare form of thymic carcinoma. We present the experience of RYTHMIC, the French national network devoted to the treatment of thymic epithelial tumors through multidisciplinary tumor boards with a review of all tumors by pathologists for classification and staging. Six cases of MNTCLH were diagnosed during a review of 1007 thymic epithelial tumors. Histologically, epithelial cells with atypia and mitoses formed micronodules that were surrounded by an abundant lymphoid background with follicles. There was neither obvious fibro-inflammatory stroma nor necrosis. Spindle cells areas were common. Initial diagnosis was micronodular thymoma in two cases, cellular atypia being overlooked, eclipsed by the micronodular pattern. Immunohistochemistry with a panel of five antibodies showed that cytokeratins (AE1-AE3) and p63-positive epithelial cells also expressed CD5 and that there was no TdT-positive cells within the tumors. CD20 highlighted the lymphoid hyperplasia. Additionally epithelial cells also expressed CD117 and diffusely Glut 1. Twenty-seven micronodular thymomas with lymphoid stroma diagnosed during the same period did not show the CD5 and CD117 positivities seen in MNTCLH and contained TdT-positive lymphocytes. Three of the 6 patients with MNTCLH had adjuvant radiotherapy. Three patients with follow-up information were alive without recurrence at 38, 51, and 95 months. Our study shows that immunohistochemistry, such as that used in the RYTHMIC network with a small panel of antibodies, may easily help to confirm the correct diagnosis of MNTCLH, a rare and low-aggressive form of thymic carcinoma, and avoid the misdiagnosis of micronodular thymoma.

Background Classification of thymic epithelial tumours (TETs) is known to be challenging; however, the level of discordances at a nationwide level between initial and expert diagnosis and their clinical consequences are currently unknown. RYTHMIC is a national network dedicated to the management of TET based on initial histological diagnosis, followed by an additional expert review of all cases. Our aim was to evaluate the discordances between initial and expert diagnoses and whether they would have led to different clinical management. Patients and methods We conducted a retrospective analysis of the cohort of patients discussed at RYTHMIC tumour board from January 2012 to December 2016. Assessment of disagreement was made for histological typing and for staging. The discordances were classified as major or minor based on whether they would have changed or not the proposed therapeutic strategy, respectively. Follow-up of the patients with major discordances was conducted until December 2018. Results Four hundred sixty-seven patients were reviewed, and 183 (39%) discordances were identified either related to histological subtype (132) and/or stage (72). Major discordances were identified in 27 patients (6%). They included 16 patients with TET for whom treatment recommendation based on the central review would have been post-operative radiotherapy, whereas it had not been the case. However, follow-up did not show any progression among the 15 patients with high-grade histology and/or stage resected thymomas. On the other hand, among the remaining 11 patients including 7 with a diagnosis other than TET, the overall management or follow-up would have been completely different with the expert diagnosis. Conclusion Our real-life cohort reveals a high level of discordances considering TET diagnosis and supports expert review for optimal clinical management.

Resume Introduction La nephropathie induite par le lysozyme est une complication rare et peu connue de la leucemie myelomonocytaire chronique. Elle est caracterisee par une toxicite vis-a-vis de l’epithelium tubulaire proximal du lysozyme produit en exces par les cellules tumorales. Nous presentons ici le cas d’une nephropathie au lysozyme dans un contexte de leucemie myelomonocytaire chronique. Observation Il s’agissait d’une patiente de 82 ans presentant une insuffisance renale aigue associee a des diarrhees et vomissements. Ses antecedents etaient marques par une leucemie myelomonocytaire chronique en surveillance simple et une hypertension arterielle. Malgre la rehydratation, la fonction renale continuait a se degrader. La biopsie renale retrouvait une nephropathie tubulo-interstitielle induite par le lysozyme avec une vacuolisation de l’epithelium tubulaire par des gouttelettes eosinophiles marquees par l’anticorps anti-lysozyme, sans localisation renale tumorale. Conclusion La nephropathie induite par le lysozyme est une pathologie rare dont le diagnostic peut etre suspecte biologiquement et confirme par une etude histologique. Les autres causes d’insuffisance renale dans un contexte de leucemie myelomonocytaire chronique doivent etre eliminees en premier lieu. Le traitement est symptomatique et s’accompagne du traitement de la pathologie hematologique sous-jacente.

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Therapies - In Press.Proof corrected by the author Available online since lundi 14 novembre 2016

Hepatosplenic T-cell lymphoma (HSTCL) is a rare and often difficult-to-diagnose subtype of lymphoma that can occur in the chronically immunosuppressed patient. We present the typical FDG PET/CT findings of HSTCL in a renal transplant recipient. The whole-body metabolic and morphologic information provided by FDG PET/CT can be of great additional value in establishing this diagnosis, thus allowing for a timely start of treatment.

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