McHugh, Kelsey

ABSTRACT Human intestinal diseases, including inflammatory bowel disease (IBD), are difficult to model because existing animal and in vitro systems do not capture the intestine’s integrated vascular, immune, and metabolic complexity. Here, we establish a custom normothermic machine perfusion platform that maintains surgically resected human intestinal tissue for up to 72 hours under near-physiological conditions. Discarded specimens from patients with nonmalignant intestinal diseases, including IBD and diverticulitis, were continuously perfused at 37°C with real-time hemodynamic and metabolic monitoring. Perfusion preserved tissue viability, mucosal architecture, epithelial integrity, oxygen consumption, metabolic activity, and vascular patency. Daily perfusate sampling enabled longitudinal profiling and experimental modulation of inflammatory mediators, revealing patient-specific immune states. This long-duration platform bridges reductionist in vitro models and clinical disease, enabling mechanistic studies of intestinal inflammation and future testing of personalized therapies in intact patient-derived tissue.

Enteroblastic, hepatoid, and clear cell carcinomas are rare subtypes of colorectal carcinoma (CRC) with histologic and immunohistochemical (IHC) overlap. We assessed 37 CRCs that possibly represent these subtypes. Provisional criteria for each subtype, along with case photomicrographs and IHC data, were circulated among the authors to provide diagnostic interpretations. Based on plurality consensus, the carcinomas were classified as enteroblastic (n=13), hepatoid (n=6), and clear cell (n=18). Unanimous agreement was reached in 18% (3 clear cell, 3 hepatoid). Interobserver analysis revealed a mean pairwise Cohen κ of 0.63 (range: 0.32 to 0.91), with the hepatoid subtype eliciting the greatest consensus. Clear cell areas were the most likely to intermix with areas of conventional CRC ( P <0.001). Seven patients (20%) had inflammatory bowel disease (mostly linked to enteroblastic CRC). Twenty-three of 34 patients (68%) had nodal metastasis, and 12 (32%) had distant metastasis (mostly to the liver) at presentation. Median recurrence-free survival was 17 months, with enteroblastic cases the most likely to recur (54%, P =0.015). Median follow-up length was 27 months, with 14 patients (40%) dying of disease (representing 7 enteroblastic, 4 hepatoid, and 3 clear cell CRC). Mutations were identified in TP53 (n=8) , APC (n=3) , FBXW7 (n=2), and KRAS (n=1). Inflammatory bowel disease significantly worsened recurrence-free survival on multivariate analysis, while distant metastasis significantly worsened both recurrence-free and overall survival on multivariate analysis. Enteroblastic, hepatoid, and clear cell CRC demonstrate morphologic and IHC overlap, leading to interobserver variability in diagnosis. Given potential differences in clinical correlations and outcomes, more refined criteria are likely necessary.

The WHO 2019 classification of digestive tract tumors introduced a high-grade (G3) category for well-differentiated neuroendocrine tumors (NETs). These neoplasms appear to have a better prognosis than poorly differentiated neuroendocrine carcinomas (NECs) and may not respond to platinum-based chemotherapy, which is the treatment of choice for NECs, justifying the creation of this new category. Most existing data on G3 NETs are derived from pancreatic neuroendocrine neoplasms, as the majority of G3 neuroendocrine neoplasms (NENs) arise there. G3 NETs are rare at extrapancreatic sites, and their prognosis and behavior are not well studied. We collected and analyzed a multi-institutional cohort of 24 extrapancreatic primary gastrointestinal G3 NETs based on mitotic rate and/or Ki67 index (5 gastric, 13 small bowel, 6 colorectal/anal). Mean Ki67 index was 29.3% (range: 10.5% to 50.2%). Cases generally showed typical well-differentiated NET morphology. Nodal metastases were present in 17/17 (100%) patients; 13/24 (45%) had distant metastases at initial presentation, and 7 patients developed them on follow-up. With a median of 29 months of follow-up, only 2 patients (8%) were alive without disease. Outcomes of G3 NETs were compared with a separate cohort of 125 extrapancreatic G1/G2 gastrointestinal NETs. G3 tumors presented at a higher pT-category stage ( P <0.001) and overall stage ( P =0.002), and patients with G3 disease were more likely to die than those with G1/G2 disease ( P <0.001). Our data show that, like pancreatic G3 NETs, rare extrapancreatic gastrointestinal G3 NETs exhibit aggressive behavior compared with their G1/G2 counterparts (although small bowel NETs tend to recur irrespective of grade). In most cases, the G3 designation is driven by Ki67 index, though exceptions exist, emphasizing the need for reviewing mitotic count in every case.

AimsWe compiled two cohorts of colorectal adenosquamous carcinoma (ASC) to describe its histologic and molecular aspects using modern parameters to compare them with literature reports using meta‐analysis of cohorts and individual case series.Methods and ResultsWe identified 53 colorectal ASC from 19 North American academic medical centres, in addition to national database reports on 94 Dutch cases. We analysed available clinical, histologic, and immunohistochemical features and patient outcome. ASC comprised 0.02% of colorectal cancers in the Dutch database. The median cohort patient ages at resection were 65 and 69 years (North American and Dutch cohorts, respectively), with a roughly equal male:female ratio. The squamous component represented between 5% and 95% of each tumour, with a median of 50%. Tumour‐infiltrating lymphocytes (TILs) were generally low (66%), and tumour budding was often Bd1 (64%). Most cases were pT3 (55%) or pT4 (40%), with nodal metastases in more than half (58%). Twenty‐three cases (43%) metastasized distantly, most commonly to the liver. Mismatch repair (MMR) deficiency was identified in 34% of the cases. Follow‐up was available for 48 patients; 13 (27%) had recurrent disease and 29 (60%) died. A total of 31 patients progressed, with median time to progression of 18 months. Available data for the Dutch cohort revealed largely similar findings, as did review of cases in the literature.ConclusionColorectal ASC usually presents at an advanced stage. Despite high rates of MMR deficiency and low tumour budding, TILs were generally low, and there is a high recurrence rate and poor prognosis.

ABSTRACTPancreatoblastoma is a rare malignant neoplasm. Cytologic diagnosis is challenging due to the tumor's heterogeneity and requirement of the presence of squamoid nests. Commonly affects children, but the tumor rarely is seen in adult patients. We are reporting three cases from two patients. First patient was a 38‐year‐old male with a mass in the pancreatic body and numerous hepatic lesions. Fine‐needle aspiration (FNA) of the pancreas showed a biphasic malignancy, predominantly composed of a primitive component with intermingled squamoid nests. Subsequent Liver FNA from the same patient showed a similar biphasic malignancy. NUT carcinoma was the top differential and was ruled out by molecular testing. Second patient was a 24‐year‐old female with a history of pancreatoblastoma related to Gardner's syndrome initially diagnosed in 2015 at age 17, status post distal pancreatectomy and chemotherapy. Celiac lymph node FNA in 2021 showed few cohesive clusters of atypical epithelioid cells, which were highlighted by beta‐catenin. Lastly, the literature was reviewed; differential diagnosis and ancillary testing were discussed.

Context.— Gastrointestinal manifestations of Kaposi sarcoma are rare but may cause morbidity. Lower gastrointestinal involvement is particularly rare, and lesions may resemble conventional bowel polyps. Objective.— To study 15 patients who presented with lower gastrointestinal tract Kaposi sarcoma with polypoid architecture. Design.— The surgical pathology files of the departments of pathology at multiple institutions were searched for cases of Kaposi sarcoma forming polyps in the lower gastrointestinal tract (jejunum, colon, rectum); 15 cases with such features were identified. Clinicopathologic information was extracted from the medical record and documented by reviewing individual hematoxylin-eosin–stained slides. Results.— The patients were 13 men and 2 women aged 26–80 years (median = 44 years). Gastrointestinal tract involvement was multifocal in 11 cases and unifocal in 4. The tumors involved the rectum, rectosigmoid junction, cecum, ascending colon, transverse colon, and descending colon and presented as polypoid lesions measuring 0.2–2.1 cm. Six patients had upper gastrointestinal tract involvement in addition to lower gastrointestinal lesions. Histologically, the tumors were characterized in 6 cases by a dense spindle cell proliferation in the lamina propria; however, the remaining cases showed only a subtle fascicular spindle cell proliferation in the lamina propria that did not form an expansile mass. Conclusions.— Biopsies of gastrointestinal polyps showing absence of the common features of hyperplastic or adenomatous polyps, particularly in immunocompromised patients, should be carefully examined for the presence of a stromal spindle cell proliferation. Use of immunohistochemical stains, particularly human herpesvirus-8, can help in establishing the correct diagnosis.

Colorectal carcinoma with sarcomatoid components (which includes so-called carcinosarcomas and sarcomatoid carcinomas) is a rare subtype with 50 reported cases in the literature and overlapping criteria with undifferentiated carcinoma. We collected and described 15 cases from 10 men and 5 women, with a mean age of 66 years. Symptoms included abdominal pain and gastrointestinal bleeding. Most tumors presented in the rectosigmoid region, with a mean size of 8.2 cm. The sarcomatoid component, on average, represented 58% of the tumors and took many forms, including spindled (10 cases), anaplastic (9 cases), and rhabdoid (3 cases); one case showed osteoid matrix. Tumor budding was usually high, and tumor-infiltrating lymphocytes were usually low. The sarcomatoid component was keratin-positive in 10 cases. One case showed loss of mismatch repair protein expression, and 2 cases showed SMARCA4 loss (1 also with SMARCA2 loss). Molecular testing identified mutations in KRAS (n=1), NRAS (n=2), BRAF (n=2), APC (n=1), and TP53 (n=1) in a few cases. Tumors often presented at advanced stage, with 11 cases pT4, 9 cases with nodal metastases, and 7 cases with distant metastases. Follow-up was available for 10 cases (median: 2 months), with 2 alive without disease, 3 alive with disease, and 5 dead. Our findings roughly corresponded with those in previously reported cases. Colorectal carcinoma with sarcomatoid components is rare and aggressive, with a poor prognosis for many patients. We suggest that spindled cells, anaplasia, heterologous elements, and/or a component with definable sarcomatous lineage be used to distinguish colorectal carcinoma with sarcomatoid components from undifferentiated carcinoma.

AbstractBackgroundAutoimmune pancreatitis (AIP) is a known mimicker of pancreatic ductal adenocarcinoma both clinically and radiologically. In this study, the authors present their institutional experience in diagnosing AIP on cytology and correlate results with the histologic findings.MethodsA 14‐year computerized search for patients who had histologically confirmed AIP with concurrent or prior cytology was performed. Clinical data, cytology findings, and surgical pathology results were reviewed for analysis.ResultsEighteen patients were identified. The patients showed a male predominance, with a mean age of 59 years. Jaundice, weight loss, and abdominal pain were the most common clinical presentation. Five of 12 patients who were tested for serum immunoglobulin G4 had elevated levels. Cytologic findings of 16 cases that were available for review showed markedly inflamed fibrous stroma (54%) and cytologic atypia (50%). The final cytologic diagnoses were suspicious for adenocarcinoma (n = 1), atypical (n = 8), and benign/negative (n = 9). The corresponding surgical pathology diagnoses were classified as type 1 (n = 10), type 2 (n = 6), and AIP, not otherwise specified (n = 2). All type 2 AIP cases had at least atypical cytologic diagnoses, with one called suspicious for adenocarcinoma and another called adenocarcinoma at the time of rapid on‐site evaluation. In contrast, eight of 10 type 1 AIP cases were negative/benign, and two of 10 were atypical. In these two atypical cases, the possibility of AIP was raised because of the presence of inflamed stroma.ConclusionAIP is a pitfall in cytology because moderate‐to‐marked atypia can be present, especially in type 2 AIP. Because atypia can be severe, the presence of cellular fibrous stroma with lymphocytic stromal infiltrates and the integration of serum immunoglobulin G4 levels could be helpful in avoiding diagnostic overcall in AIP.