The human tumor phenotype referred to as MSI (Microsatellite Instability) is associated with inactivating alterations in MMR genes (Mismatch Repair). MSI was first observed in inherited malignancies associated with Lynch syndrome and later in sporadic colon, gastric and endometrial cancers. MSI tumors develop through a distinctive molecular pathway characterized by genetic instability in numerous microsatellite DNA repeat sequences throughout the genome. In this article, french researchers and physicians who have been recently awarded by the Fondation de France (Jean and Madeleine Schaeverbeke prize) make a sum of their activity in the MSI cancer field for more than 20 years. Their findings have greatly contributed to increase our knowledge of this original cancer model, laying the foundation for a personalized medicine of MSI tumors.

Currently, about 50% of newly prostate cancers are localized and low-risk according to D'Amico risk classification. Focal therapies whose objective is to treat only the index lesion appear as a new alternative being evaluated in the management of these cancers. Besides the interest in the control of the disease, focal therapies present a very low risk of morbidity. Vascular targeted photodynamic therapy (VTP) is one of these new emerging therapies.

Neoadjuvant therapy is an increasing treatment option in the management of breast cancer. The tumor response to neoadjuvant therapy, especially the pathological complete response, is a validated endpoint frequently used in clinical trials. However, there is still a lack of standardization for the surgical specimen management in the neoadjuvant setting. This leads to heterogeneity in the specimen handling and might lead to significant bias for the prognostic assessment of patients or in clinical trials. The GEFPICS group, composed of expert breast cancer pathologists, herein presents guidelines for the management of breast and axillary specimen before treatment (management of biopsy, items of the pathological report) and after neoadjuvant therapy (specimen handling, histological assessment of response, items of the pathological report and response grading systems).

Extra-uterine leiomyomatosis is a rare pathology defined by the presence of benign smooth uterine muscle cells in unusual localizations, including different entities. It mainly affects premenopausal women with a medical history of uterine myoma with or without surgical treatment. Three main types are discribed: intraveinous leiomyomatosis, benign metastatisizing leiomyoma and leiomyomatosis peritonealis disseminata. The diagnosis may be complex with many differential diagnosis, and relies on histology. The treatment depends on multiple factors such as age, localization, size, symptoms and associated comorbidities. It is based on surgical resection and hormonal privation, surgical (adnexectomy) or medical (hormonotherapy). There is a high risk of recurrence. Some malignant evolutions have been reported, mostly leiomyosarcoma following peritoneal disseminated leiomyomatosis. Long term follow-up of these patients is mandatory. A particular manifestation of extra-uterine leiomyomatosis is the hereditary leiomyomatosis and renal cell carcinoma (HLRCC) syndrome. It is an autosomal dominant disorder which confers an increased risk of cutaneous and uterine leiomyomas and renal cell cancer, with a poor prognosis due to the urologic tumor.

As for the Bethesda system for cervical and thyroid cytopathology, a terminology for reporting urinary cytology has been published in 2015. The new "Paris System" provides a consensus terminology for urinary cytology which underlines the criteria for the recognition of high-grade urothelial carcinoma (HGUC) and of those excluding HGUC, or suspicious for HGUC. It also focuses on new rules to recognize and report the subgroup of "atypical urothelial cells". Here we describe and illustrate the various categories as in the reference book. We analyse the main diagnostic criteria, including microscopic features as well as the risk of malignancy associated to every diagnostic category.

Dysplasia is a preneoplastic lesion. Histological diagnosis is based on the presence of architectural and cytological modifications, and dedifferentiation, which the intensity is variable. Dysplasia is commonly graded as low and high grade. We achieved a retrospective study of 90 cases of gastrointestinal dysplasia collected in the Department of Pathology of Hassan II university hospital of Fez, during a period of 3 years. The cases were reviewed independently and blindly without clinical information by two pathologists. Their diagnoses were compared to the initial diagnosis. Interobserver concordance in the diagnosis of the degree of dysplasia was evaluated. The average age of our patients was 56 years oldwithout predominance of sex. The interobserver concordance in the diagnosis of digestive dysplasia between the three pathologists was moderate (with a Kappa estimated at 0.42). Concordant diagnosis for digestive low grade dysplasia was observed in 50 cases of the 55 cases (90%) and only 18 cases of high-grade dysplasia of 35 cases studied (50%). The agreement for the low-grade dysplasia is more significant. However, there is significant variation in the analysis of high-grade dysplasia. This work reveals a moderate reproducibility in the diagnosis of gastrointestinal dysplasia lesions and mostly well marked for high-grade dysplasia.

BAF complexes are chromatin remodelling complexes made up of 15 subunits which overview transcription regulation. A subset of their subunits are notoriously linked to cancer, with the examples of SMARCB1, SMARCA4, ARID1A/1B and PBRM1. The complexes act as tumor suppressor genes, commonly mutated in a wide array of malignancies with an overrepresentation of sarcomas and tumors of the central nervous system. The recurrent inactivation of their genes points towards their driving role in the tumorigenesis of SMARCB1 in malignant rhabdoid tumors and SMARCA4 in small cell carcinoma of the ovary, hypercalcemic type. These tumors are morphologically similar composed of solid sheets of cells displaying vesicular nuclei dotted with clear chromatin and conspicuous nucleoli. Genomically, they share simple diploid profiles with no other alterations than in the culprit gene. Other mesenchymal tumors, distinct from malignant rhabdoid tumors are associated with BAF alterations, namely epithelioid sarcomas, SMARCA4-deficient thoracic sarcomas. BAF subunits are mostly inactivated through mutations or deletions but also occur through translocations in medullary carcinoma of the kidney and synovial sarcomas. Apart from tumors displaying recurrent alterations of the complexes, some variants or tumor variants display BAF alterations, including epithelioid malignant peripheral nerve sheet tumors and poorly differentiated chordomas. Lastly, some malignancies display low frequency of BAF alterations, in keeping with their passenger role in tumorigenesis with the example of dedifferentiated carcinomas, especially in colon, lung and uterus. BAF complexes alterations correlate with morphological features recognizable by microscopy, paving the way for their routine diagnosis and potential therapeutic prospects.

Gastrointestinal tract ganglioneuromatosis is a rare condition, which is isolated or included in a syndromique disease. Multiple endocrine neoplasia type 2 is the most frequently associated syndrome. Association with type 1 neurofibromatosis has also been established, but much rarely. We report the case of large bowel ganglioneuromatosis found incidentally in a patient with type 1 neurofibromatosis.

Pulmonary metastases due to a pancreatic cancer are difficult to diagnose and demonstrate a wide range of radiological patterns. We report the case of a 37-year-old female patient, without past medical history, with multicystic lung disease in a context of chronic abdominal pain, fatigue and weight loss. After several months of diagnostic delay, pathological examination of surgical lung biopsies led to the diagnosis of secondary deposits of pancreatic cancer. The clinical and radiogical situation deteriorated quickly with the development of alveolar consolidation and Aspergillus superinfection was then diagnosed. This case illustrates the value of an early decision to undertake surgical lung biopsy in the work-up of multicystic lung disease when cancer is suspected. In addition, in the specific context of cancer, faced with clinical and/or radiological deterioration, it is essential to look for infection, particularly aspergillosis.

Weber christian's disease or idiopathic panniculitis is a rare condition characterized by an inflammation of the subcutaneous adipose tissue; it is a non-specific pathological condition that remains a central issue of debate and whose outcome is unpredictable. We here report the case of a 9-month-old female infant admitted in the hospital with sepsis preceded by respiratory symptoms and followed by the occurrence of small, hard, susceptible, asymmetrical erythematous subcutaneous nodes located in the arms and lower limbs. Cutaneous biopsy showed lobular hypodermitis with polymorphonuclear neutrophil infiltrations. The diagnosis of Weber Christian's disease was retained after eliminating other differential diagnoses. The patient was treated with prednisone with good outcome; during the follow-up period and during disease regression the diagnosis of B-cell acute lymphoblastic leukemia was made; this uncommon outcome has never been described in the literature. The aim of this study is to discuss any similar situation where another diagnosis was made in patients initially treated for idiopathic lobular panniculitis. This highlights the need for exhaustive etiological investigations and prolonged monitoring in order to search for a possible associated disorder.

Skin metastases from bronchogenic carcinoma are rare, indicating advanced disease. We here report a case of skin metastasis from bronchial adenocarcinoma treated surgically in order to improve patient comfort.

Darier and Ferrand dermatofibrosarcoma (DFS) is a rare skin tumor characterized by its local aggressiveness and a high risk of recurrences. Prognosis depends essentially on the quality of treatment. Complete response in Darier and Ferrand dermatofibrosarcoma with healthy margins, initially judged inoperable after 1 year of neoadjuvant imatinib-based treatment, has been rarely described in literature. We here report the case of a young female patient treated in the Department of Medical Oncology in FES for locally advanced DFS with complete response, in order to assess the role of imatinib and of targeted therapies in the treatment of DFS.

Osteochondroma is the most common benign bone tumor. It usually affects the metaphyses of the long bones, in particular around the knee and the proximal humerus. It very rarely affects the pubic symphysis, usually with an atypical symptomatology. We here report the case of a 35-year old man in whom osteochondroma in the pubic symphysis encroaching on the iliopubic branch was fortuitously discovered. Radiological examinations as well as macroscopic and histological examination confirmed the diagnosis and the absence of signs of malignancy.