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Rosai-Dorfman-Destombes disease is a rare non-Langerhansian cell histiocytosis characterized by the accumulation of large activated histiocytes in the affected tissues with images of emperipolesis. The diagnosis is not really problematic in the classical forms, with a lymph node presentation, whose histology is very suggestive. However, it can be much more difficult in the extra-nodal forms, which are misleading in both their clinical and histological presentation. We report here a case illustrating this diagnostic difficulty. Firstly, clinically, the disease was revealed by an unusual laryngeal location, responsible for acute obstructive respiratory distress and requiring urgent surgical management. Secondly, histologically, the diagnosis was not evoked in the first instance by analysis of the laryngeal lesion. Indeed, there was a not specific appearing polymorphic infiltrate, associating small lymphocytes, plasma cells and numerous histiocytes, without evidence for a lymphoma after immunohistochemistry and lymphocyte clonality analysis. However, after re-examination of the slides, the histiocytes sometimes appeared large or xanthomised and have a PS100+, CD1a-, langerhine- phenotype, with rare images of emperipolesis. These aspects finally suggested the diagnosis of Rosai-Dorfman-Destombes disease, then confirmed by a cervical lymph node biopsy showing characteristic histological features. Simultaneously, NGS analysis of the laryngeal lesion showed a mutation in the MAP2K1 gene, in accordance with the diagnosis. The patient was treated with revlimid and dexamethasone for 6 months, with complete remission, and is currently undergoing maintenance treatment with revlimid.

Resume La syphilis est une infection sexuellement transmissible en recrudescence, due a la bacterie spirochete Treponema Pallidum. La lymphadenite syphilitique peut s’observer aux 3 stades de la maladie. Son diagnostic histologique reste souvent un challenge pour le pathologiste car l’aspect peut etre tres trompeur et mimer des pathologies aussi bien reactionnelles que tumorales lymphomateuses. Nous rapportons le cas d’un homme jeune infecte par le VIH adresse pour une suspicion de lymphome agressif. L’analyse histologique et immunohistochimique de l’adenopathie cervicale a revele une syphilis secondaire.

Syphilis is a resurging sexually transmitted infection linked to Treponema Pallidum. Syphilitic lymphadenitis can be present during the 3 stages of the disease. Its histological diagnosis remains challenging for the pathologist given its possible misleading aspect and its ability to mimic as well as reactional as tumoral conditions. We report the case of an HIV-infected young patient referred for suspicion of an aggressive lymphoma. Histological and immunohistochemical analysis of cervical lymphadenopathy revealed secondary syphilis.

International audience; INTRODUCTION: Diffuse malignant mesothelioma (MMD) is a rare disease. The diagnosis is difficult and needs an antibody panel. The tumor suppressor gene BRCA1 associated protein 1 (BAP1) is involved in several cancers, including MMD. Loss of BAP1 expression is correlated with BAP1 somatic or constitutional genetic defects. Our work assesses the value of integrating BAP1 in the panel of antibodies used for the diagnosis of MMD. MATERIALS AND METHODS: Immunohistochemical techniques were performed on cytological and histological specimens of MMD and adenocarcinoma pleural metastasis. RESULTS: Of the 26 patients with MMD and the 24 patients with adenocarcinoma pleural metastasis, loss of BAP1 expression was observed in 11 (48%) and one adenocarcinoma (6%) on cytological specimens and in 12 MMD (48%) and in one adenocarcinoma (5%) on biopsy specimens. The concordance between immunocytochemistry and immunohistochemistry was 100%. The specificity of BAP1 was 100% on cytological and biopsy specimen for the diagnosis of malignancy in case of mesothelial proliferation. DISCUSSION AND CONCLUSION: Loss of BAP1 expression is an indicator of MMD in a context of mesothelial proliferation. This immunohistochemistry could be integrated in the panel of immunostaining used for MMD diagnosis, either on histological or cytological samples. Furthermore, loss of BAP1 expression guides the patient to an oncology genetic counseling in order to eliminate a MMD developed as part of a constitutional genetic defect

Les lymphomes B diffus a grandes cellules (LBDGC) comportant un rearrangement chromosomique du gene MYC representent environ 10 % des LBDGC. Ils sont souvent refractaires aux therapeutiques standards et associes a un pronostic pejoratif. L’indication d’une etude cytogenetique par hybridation in situ en fluorescence (FISH) pour identifier ces cas n’est pas consensuelle. C’est pourquoi nous avons compare 45 cas de LBDGC avec rearrangement du gene MYC (MYC + ) a 45 cas sans rearrangement (MYC−) dans une etude retrospective realisee a partir des archives du service d’Anatomie Pathologique du Centre Hospitalier Lyon-Sud. Le rearrangement du gene MYC etait detecte par technique de FISH a l’aide d’une sonde break-apart (SPEC MYC–Zytovision®). La presence du rearrangement etait comparee aux donnees cliniques (âge, sexe, antecedent de lymphome folliculaire, localisation), morphologiques (type histologique, architecture, aspect en ciel etoile, variante cytologique) et immunohistochimiques (phenotype centrofolliculaire ou post-germinatif, Ki67, BCL-2, BCL-6, MYC). Le phenotype etait evalue par immunohistochimie selon l’algorithme de Hans et par technique de Reverse Transcriptase Multiplex Ligation-dependent Probe Amplification (RT-MLPA). Concernant la presentation clinique, il n’y avait pas de difference statistiquement significative entre les deux groupes. Une morphologie intermediaire (lymphome de Burkitt/LBDGC) et une cytologie immunoblastique etaient plus frequentes dans le groupe MYC+ (respectivement 20/45 cas, 44 % et 17/45, 38 %) que dans le groupe MYC- (8/45 cas, 18 % et 6/45, 13 %) (p

Pseudomyxoma peritonei is a clinical entity characterized by a gelatinous ascite associated with mucinous tumor deposits spreading on peritoneal surface and potentially invading abdominal organs. It is considered as a tumor process linked, in most of cases, to a mucinous appendiceal neoplasm. Pseudomyxoma peritonei may benefit from a therapeutic strategy combining cytoreductive surgery and intra-peritoneal chemotherapy, which has led to a major prognosis improvement. Different classifications are available and the last one corresponds to the WHO 2010 version, which individualizes pseudomyxoma peritonei in two classes: low grade and high grade mucinous carcinoma. The very low frequency of this entity and its specific therapeutic strategy need specific health care centres, as well as physicians and pathologists collaborating through dedicated networks. The aim of this article is to summarize the pathology, causes, mechanisms and therapeutic approaches of pseudomyxoma peritonei, as well as their interfaces with dedicated networks.

As part of the national 2009-2013 Cancer Plan, and with the support of the National cancer Institute and the French ministry of health, the National network for the treatment of rare peritoneal malignancies (RENAPE) has been organized. Its main objective is to optimize the framework for the healthcare management and treatment of rare peritoneal malignancies. This specific organization covers the whole national territory including clinical expert and specialized structures and should lead to an appropriate treatment based on expertise and proximity. Within the RENAPE network, the RENA-PATH group gathers the pathologists actively involved in the management of rare peritoneal malignancies. The actions of RENA-PATH are focused primarily on the harmonization of pathological diagnostic criteria, reporting of new cases in the RENAPE registry and histology reviewing.

Synovial sarcoma most commonly occurs in the peri-articular regions of the extremities. We report a case of primary pulmonary monophasic synovial sarcoma. This tumor is extremely rare and shows a particular immunohistochemical pattern of great help for the diagnosis. Cytogenetic study confirm the diagnosis by showing the specific t (X; 18) chromosomal translocation, characteristic of synovial sarcoma in all anatomic locations.

Les lymphomes B de la zone marginale, splenique et ganglionnaire, sont des entites recemment decrites dans les classifications de lymphomes (REAL/OMS) et qui sont encore mal caracterisees sur le plan moleculaire. La contrepartie cellulaire normale des cellules lymphomateuses et le role eventuel d’un antigene dans la selection du clone tumoral sont peu connus. C’est pourquoi nous avons souhaite determiner le profil des mutations somatiques des genes des immunoglobulines dans ce type de lymphome, profil qui a permis recemment de clarifier certains points de l’ontogenese d’autres syndromes lymphoproliferatifs. Pour etablir ce profil, la region variable (VDJH) de la chaine lourde des genes d’immunoglobuline a ete sequencee a partir des echantillons obtenus chez 49 patients atteints par ce lymphome. Sur les 35 formes spleniques, 11 cas etaient non mutes alors que 2 cas ganglionnaires seulement etaient non mutes sur 14 cas. Chez 3 patients, une diversite intra-clonale a ete mise en evidence, suggerant que la cellule a l’origine du lymphome puisse subir de nouvelles mutations somatiques apres l’apparition du processus oncogenique. Un biais d’utilisation des segments VH a ete retrouve avec une surrepresentation de la famille VH1, en particulier VH1-2 04 dans les formes spleniques (8/35), et VH4, en particulier VH4-34 dans les formes ganglionnaires (7/14). Cinq cas (4 spleniques et 1 ganglionnaire) ont presente la meme utilisation (avec un profil de mutation different) de VH1-2 04, DH3-3 et JH4, avec peu ou pas de mutations (96 a 100 % d’homologie). Ces resultats indiquent la presence d’une selection par l’antigene des clones de cellules B a l’origine de la tumeur et font suspecter l’existence d’antigenes communs. Cependant la mise en evidence d’une empreinte de maturation d’affinite par selection antigenique du clone tumoral a ete observee dans seulement 9 cas, suggerant une selection par des antigenes T-independants. Aucune correlation significative n’a ete retrouvee entre l’utilisation des segments, le niveau de mutations et les donnees cliniques ou morphologiques a l’exception d’une association entre un profil non mute et la presence d’une t (11 ; 14) d’une part et la perte allelique de TP53 d’autre part. La relation entre l’absence de mutation et la deletion homozygote de p53 suggere que ces patients constituent un groupe particulier. Cependant aucun lien entre l’activite biologique de p53 et le mecanisme des mutations somatiques n’a ete mis en evidence. Aucune association avec le virus de l’hepatite C (1 cas) et en particulier l’utilisation des VH n’a ete retrouvee. Ces resultats confirment l’heterogeneite moleculaire et probablement cellulaire de cette pathologie qui est refletee par l’heterogeneite clinique et morphologique decrite dans ce type de lymphome.