Synchronous and metachronous primary colorectal cancers with concordant and discordant mismatch repair status.

Multiple primary colorectal carcinomas (CRCs) synchronous, when detected approximately at the same time, or metachronous, when a significant amount of time has elapsed between diagnoses can show both mismatch repair (MMR) status concordance and discordance between primary tumors. The aim was to evaluate the MMR status of a monoinstitutional, retrospective cohort of synchronous and metachronous CRCs, with a focus on the frequency of cases with discordant MMR status, and explore the MMR status of metastatic nodal deposits. All synchronous and metachronous CRCs diagnosed in our institution between 2011 and 2023 were collected. Clinicopathologic characteristics were evaluated, including MMR status of all CRCs, BRAF mutation, and MLH1 promoter methylation analyses. MMR status discordant cases were further analyzed, and MMR testing was performed on nodal metastases. Of 3671 patients, 107 (2.9%) had multiple CRCs (94 synchronous and 13 metachronous; total number of CRCs 220). Sixty CRCs were MMR deficient (dMMR) (27.3%), and most were right-sided and high-grade and showed special histologic features (P < .00001). Ninety-three patients showed intertumoral MMR concordance: 70 (65.4%) with MMR-proficient (pMMR) CRCs, and 23 (21.5%) were dMMR. Fourteen patients (13.1%) showed intertumoral MMR discordance (at least one dMMR and one pMMR), and in 5 patients, nodal metastases were present: 2 patients harbored metastases only from their pMMR cancer, 2 only from their dMMR cancer, and in 1 patient both pMMR and dMMR metastases were present. In conclusion, all multiple primary CRCs should be analyzed for MMR status as discordant MMR is possible as well as discordant metastatic nodal deposits, and this may be important for patient management.

Dasatinib-induced Crohn's-like colitis.

Dasatinib is a second-generation multityrosine kinase inhibitor used in the first-line and second-line treatment of Philadelphia chromosome-positive leukaemia. The most frequent type of Dasatinib-induced intestinal injury is haemorrhagic colitis; other morphologic patterns include apoptotic colopathy, CD8+ T-cell-mediated colitis and non-specific colitis. Aim of this study is to describe a novel Crohn's-like histopathologic pattern of Dasatinib-induced colitis. Four patients developed diarrhoea during Dasatinib treatment; colonoscopy was performed and biopsy sets were taken for histological analysis. All patients showed patchy, chronic active inflammation with cryptitis and microgranulomas (two patients). Ileal and rectal biopsies showed either no or mild, focal inflammation. An increase in lamina propria eosinophils was seen (two patients) and apoptoses were seen (three patients). Complete remission was observed after interruption of treatment. Dasatinib-induced colitis and Crohn's disease may share histologic features including microgranulomas, which can potentially lead to misdiagnosis if no information on treatment is provided.

Pathologist's approach to paediatric and neonatal eosinophilic gastrointestinal disorders.

Children are not simply miniature adults. The evaluation of their gastrointestinal disorders is therefore different from that in full-grown adults and requires a particular clinical/pathologic approach.Different studies have tried to assess the normal eosinophil distribution in the gastrointestinal tract in adults while very few studies have investigated the paediatric population, consequently complicating the pathologist's ability in identifying an abnormal number of eosinophils in this setting of patients.When evaluating gastrointestinal tract biopsies with eosinophilia, eosinophilic count must be considered along with other histological features like eosinophil distribution in the gastrointestinal wall, their degranulation, cryptitis and crypt abscesses, other accompanying inflammatory cells, apoptotic bodies, foreign material or microorganisms; these findings, although rarely specific, may be a useful aid for diagnosis.Reports should not include a diagnosis of primary eosinophilic gastrointestinal disorders (EoGID) if clinical data and test results do not rule out other forms of gastrointestinal eosinophilia. A more descriptive definition like "with eosinophilic pattern" should be favoured over a specific diagnosis of "eosinophilic disorder" in order to avoid potential confusion between different entities.

"Stranger things" in the gut: uncommon items in gastrointestinal specimens.

Organic (such as parasites or vegetable remnants) and inorganic substances may be encountered during routine pathology diagnostic work up of endoscopic gastrointestinal biopsy samples and major resections, causing possible diagnostic conundrums for the young and not so young pathologists. The main aim of this review is the description of the most frequent oddities one can encounter as foreign bodies, in gastrointestinal pathology, on the basis of the current literature and personal experience. The types of encountered substances are divided into four principal categories: parasites (helminths such as Enterobius vermicularis, Strongyloides, Schistosoma, and Anisakis, and protozoa such as Entamoeba, Giardia and some intestinal coccidia); drugs and pharmaceutical fillers (found as deposits and as bystanders, innocent or not); seeds (possibly confused with worms) and plant remnants; pollutants (secondary to post-resection or post-biopsy contamination of the sample). An ample library of images is provided in order to consent easy referencing for diagnostic routine.

Oligodendroglioma with ganglioglioma-like maturation: the histopathological diagnostic challenge of a brain neoplasm with aberrant neuronal component - A case report and review of the literature.

Background: Oligodendroglioma with ganglioglioma-like maturation is a rare entity not included in the 2016 World Health Organization Classification of Tumors of the Central Nervous System. To date, only a few cases were described in the literature. We report a case of this tumor, along with a review of the previous case reports/ series. Case Description: A 63-year-old man with a left frontal mass and a 2-month history of seizures underwent surgical resection in our center. Grossly, the specimen appeared as a yellowish mass with prominent hemorrhagic component. Microscopically, the lesion was composed by small round cells often surrounded by a clear halo and, near the hemorrhagic area, by scattered large cuboidal cells with vesicular nuclei and prominent eosinophilic nucleoli. On immunohistochemical stains, both cells components tested positive for ATRX, p53, and GFAP; larger ganglion-like cells showed synaptophysin and chromogranin-A expression. IDH1 codon 132 mutation, 1p-19q-codeletion, and MGMT methylation were observed. Eventually, a diagnosis of oligodendroglioma (the WHO grade II) with ganglioglioma-like maturation was rendered. The patient received adjuvant chemotherapy and is currently alive and asymptomatic. Conclusion: Recognition of ganglioglioma-like maturation in oligodendrogliomas may prevent undertreatment of these neoplasms. To this end, fluorescence in situ hybridization assays are crucial for defining the 1p-19q status.