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Morphological sciences have recently experienced a significant technological breakthrough that offers new opportunities for cell and tissue imaging in situ but also raises new challenges to pathologists, who must adapt to a rapidly evolving environment. New partners, such as cell and molecular biologists, have provided pathologists with highly powerful tools for cell and subcellular imaging. They include: (a) the adaptation of techniques derived from molecular biology and cytogenetics, (b) the development of new microscopic tools, such as confocal microscopy, and (c) the emergence of new preparative techniques, such as microdissection or tissue arrays. However, recent technological progresses in various fields, from endoscopy to genomics, also raise new challenges to pathologists. Pathologists must therefore be prepared to redefine their area of expertise: this will be achieved through a continuous collaboration with all the partners involved in cell and tissue imaging and analysis but also by emphasising the importance of the informations provided by cell and tissue imaging in situ.

Background Sarcoma represents a morphologically heterogeneous group of malignant tumours, accounting for 1% of malignancies. Given the rarity of cases and the multiplicity of histological types, the diagnostic is difficult to perform. Nevertheless, accurate initial histological diagnosis is essential for adequate management. Over a 1-year period, we conducted a prospective and exhaustive study of the medical management of patients with sarcoma to identify determinants of medical practices and to realise a centralised and systematic review of all cases diagnosed within the Rhone-Alpes (RA) region. The goal of this work was to assess the impact of a systematic pathological review on management of patients. Design All suspicions of sarcoma arising in patients diagnosed in the RA region were collected over a 1-year period. Firstly, the initial diagnosis was compared with the corresponding expert opinion. The concordance between the two diagnoses was assessed according to three defined levels as follows: (0) absolute mismatch when the difference observed between the two diagnoses was major for example, sarcoma vs benign soft tissue tumour or non-sarcoma (melanoma, carcinoma, lymphoma), or misidentification of the histological type of sarcoma potentially resulting in important therapeutic impact (eg GIST vs non GIST); (1) partial concordance when the inconsistency concerned the grade or the sarcoma subtype (eg, dedifferentiated liposarcoma vs myxoid round cell liposarcoma), and (2) absolute concordance when the two diagnoses were identical. Second, cases were separated into two main groups: cases sent for the systematic review (SR) induced by this study and cases addressed for the study and also for a second opinion due to the difficulties to propose a diagnosis (SO). Within each group, the similarity of the two diagnoses was assessed using the same methodology with the 3 defined levels previously described. Results 366 cases were analysed. Concordance analysis showed 19% of absolute mismatch (70/366), 27% of partial concordance (97/366) and 54% of absolute concordance (199/366). Among the absolute mismatches, 8% (30/366) were initially diagnosed as benign soft tissue tumour or nonsarcoma tumour and were sarcoma after expert review, 3% (10/366) were initially diagnosed as sarcoma and were not sarcoma after expert review and 8% (30/366) were misidentification of the histological type of sarcoma. Among partial concordances 8% (30/366) were related to histological subtypes and 19% (67/366) were related only to histological grade. SO represented 51% of the cases (188/366) and SR the remaining 49% (178/366). Within the SR group, the three types of concordance rates observed were: 9% (17/178) of absolute mismatch, 25% (44/178) of partial concordance, and 66% (117/178) of absolute concordance. Within the SO group, the absolute mismatch rate reached 28% (53/188), and there was 28% (53/188) of partial concordance and 44% (82/188) of total concordance. Conclusions 46% of first histological diagnoses were modified with second exert opinion. 27% of cases were concerned by a difference in histological type or subtype and 19% were absolute mismatch resulting in therapeutic impact. The high rate of SO (51% in this study) shows that pathologists are aware of the difficulties they face to make reliable diagnosis in this complex pathology. In this group, the high rate of absolute mismatch (28%) demonstrates that an expert SO is justified. The 9% absolute mismatch rate within a group of patients that would not have benefited from any review without this study (SR) shows the necessity to extend the expert process and to continue pathologists training. Systematic SO improves the quality of diagnosis and clearly benefits patients. Even if more costly in short term, optimal therapeutic management eventually results in reduced overall health care spending. Contexte Les sarcomes representent un groupe de tumeurs tres heterogenes, comptant pour 1% de l9ensemble des tumeurs malignes. Etant donne la rarete des cas et la multiplicite des types histologiques, le diagnostic histologique est difficile a etablir. Neanmoins, un diagnostic histologique initial precis est essentiel pour une prise en charge medicale adequate. De ce fait, nous avons conduit pendant un an une etude prospective et exhaustive de la prise en charge medicale des patients atteints de sarcome dans le but d9identifier les determinants des pratiques medicales et de realiser une relecture systematique des sarcomes diagnostiques en region Rhone-Alpes. L9objectif de ce travail etait d9estimer l9impact d9une relecture pathologique ssytematique sur la prise en charge des patients. Programme Toutes les suspicions de sarcomes diagnostiquees en region Rhone-Alpes ont ete collectees durant une periode de un an. En premier lieu, le diagnostic initial a ete compare avec celui de la relecture par le pathologiste expert. La concordance entre les deux diagnostics a ete etablie selon trois niveaux, definis de la facon suivante: (0) discordance totale lorsque la difference observee entre les deux diagnostics etait majeure, par exemple un diagnostic de sarcome vs un diagnostic de tumeur benigne ou de tumeur non sarcomateuse, ou une erreur dans le type histologique ayant un impact therapeutique important (par exemple GIST vs non GIST); (1) concordance partielle lorsque la difference entre les deux diagnostics concernait le grade ou le sous-type histologique (par exemple liposarcome dedifferencie vs liposarcome myxoide), et (2) concordance totale lorsque les deux diagnostics etaient identiques. En second lieu, les sarcomes ont ete separes en deux groupes: les cas ayant ete envoyes pour la relecture systematique conduite dans cette etude et les cas ayant ete envoyes spontanement lors d9une demande de second avis. Pour chacun des deux groupes, la concordance entre les diagnostics a ete etablie selon la meme methodologie. Resultats 366 suspicions de sarcome ont ete analysees. L9etude de la concordance des diagnostics a montre une discordance totale pour 19% des cas (70/366), une concordance partielle pour 27% des cas (97/366) et une concordance totale pour 54% des cas (199/366). Parmi les discordances totales, 8% (30/366) des cas ont ete diagnostiques initialement comme des tumeurs benignes ou des tumeurs non sarcomateuses alors que le diagnostic de sarcome a ete avere apres la relecture, 3% des cas (10/366) ont ete diagnostiques initialement comme des sarcomes et ne l9etaient pas apres la relecture par l9expert et 8% (30/366) comprenaient une erreur dans le type histologique du sarcome. Parmi les concordances partielles, 8% (30/366) etaient lies au sous-type histologique et 19% (67/366) etaient lies uniquement au grade histologique. Les demandes de second avis spontanes representaient 61% des cas (188/366) et la relecture systematique les 49% restants (178/366). Dans ce dernier groupe les taux de concordance observes etaient: 9% (17/178) de discordance totale, 25% (44/178) de concordance partielle et 66% (117/178) de concordance totale. Dans le groupe des demandes de second avis le taux de discordance totale atteignait 28% (53/188) le taux de concordance partielle 28% (53/188) et le taux de concordance totale 44% (82/188). Discussion 46% des dignostiques histologiques initiaux ont ete modifies suite a la relecture histologique. 27% des cas etaient concernes par une difference dans le type ou le sous-type histologique et 19% etaient des discordances totales ayant un impact therapeutique. Le taux eleve de demandes spontanees de second avis (51%) montre que les pathologistes sont conscients des difficultes qu9ils rencontrent pour etablir des diagnostics fiables dans cette pathologie complexe. Dans ce groupe le taux eleve de discordance totale demontre que la relecture histologique est justifiee. Le taux de discordance totale de 9% dans le groupe de patients qui n9aurait pas beneficie de relecture sans cette etude montre la necessite d9etendre la relecture par un expert et de continuer la formation des pathologistes. La relecture systematique ameliore la qualite du diagnostic et beneficie clairement au patient. Meme si elle est plus couteuse a court terme, une prise en charge therapeutique optimale conduit a la reduction des depenses globales de sante.