Spontaneous Tumor Lysis Syndrome Secondary to Metastatic Pancreatic Adenocarcinoma.

Spontaneous tumor lysis syndrome (STLS) secondary to metastatic pancreatic adenocarcinoma is a rare clinical phenomenon. An 86-year-old woman with a history of pancreatic cysts presented to the emergency department with progressive fatigue, transaminitis, elevated lactate dehydrogenase, and acute kidney injury of unclear etiology. Abdominal imaging and celiac lymph node biopsy were consistent with metastatic pancreatic adenocarcinoma. Her clinical status deteriorated requiring intensive care unit transfer, and her laboratory results were found to be consistent with STLS. Despite treatment, she entered multisystem organ failure and died shortly after. This case adds to the literature of STLS in pancreatic adenocarcinomas.

Emerging and under-recognised patterns of colorectal carcinoma morphologies: a comprehensive review.

While the overwhelming majority of colorectal carcinomas (CRC) are diagnosed as adenocarcinoma not otherwise specified, there are numerous under-recognised morphologic patterns of CRC. These patterns are recognised by the WHO, appear in reporting manuals for the American Joint Committee of Cancer, and/or are listed on synoptic reports, while many other variants have either fallen out of favour or are emerging as future bona fide patterns. Herein, we discuss 13 variants: serrated adenocarcinoma, micropapillary adenocarcinoma, medullary carcinoma, neuroendocrine carcinoma, mucinous adenocarcinoma, signet-ring cell carcinoma, adenosquamous carcinoma, adenoma-like adenocarcinoma, lymphoglandular complex-like CRC, carcinoma with sarcomatoid components, cribriform-comedo-type adenocarcinoma, undifferentiated carcinoma and low-grade tubuloglandular adenocarcinoma. The purpose of this review is to scrutinise these variants by assessing their clinical characteristics, morphologic cues, as well as pitfalls, and address their prognostic significance. Our analysis aims to bring clarity and updated understanding to these variants, offering valuable insights for pathologists. This contributes to more nuanced CRC diagnosis and treatment strategies, highlighting the importance of recognising a broad spectrum of morphologic patterns in CRC.

Gastrointestinal stromal tumors in fine-needle aspiration biopsies.

Gastrointestinal stromal tumors (GISTs), although rare, are the most common mesenchymal neoplasms of the gastrointestinal tract. Their potential for malignancy underscores the significance of identifying them through cytomorphologic findings and pertinent immunohistochemical markers. GISTs can emerge anywhere along the gastrointestinal tract with a predilection for the stomach. The clinical manifestations vary from nonspecific abdominal symptoms to incidental discovery during diagnostic interventions for unrelated signs and symptoms. Cytologically, GIST aspirates contain spindle or epithelioid cells with immunoreactivity for CD117/c-KIT, DOG-1, and CD34. Molecularly, KIT or PDGFRA mutations are prevalent, guiding targeted therapy with tyrosine kinase inhibitors. Distinct subtypes like succinate dehydrogenase-deficient GISTs pose challenges, often affecting younger individuals and displaying unique features. Histologically, GISTs are graded by mitotic rates, aiding prognostication. Distinguishing GISTs from similar entities is pivotal, necessitating attention to their immunostaining patterns for making an accurate diagnosis and molecular alterations for effectively planning treatment. Common differential diagnoses include leiomyoma, schwannoma, and solitary fibrous tumor. This article presents a classic GIST case and showcases relatively simple diagnostic clues for identifying similar lesions that may occur in diverse locations.

Case report and mini-review: Sarcina ventriculi in the stomach of an 80-year-old female.

Sarcina ventriculi, also known as Zymosarcina ventriculi and, incorrectly, as Clostridium ventriculi, is rarely encountered in clinical settings. A patient with a complicated gastrointestinal (GI) history, who was acutely presenting with small-bowel obstruction, was found to be colonized by S. ventriculi. The distinctive morphology of this species, with large Gram-variable cocci (up to 3 µm) arranged in two-by-two cuboid clusters reaching up to 20 µm, was key in identifying this bacterium in a stomach biopsy specimen. Sarcina ventriculi appears to be ubiquitously found in nature, and related bacterial species can cause GI-related disease in various animals. Clinical manifestations in humans are broad and often related to other underlying comorbidities. Isolation of S. ventriculi in the laboratory requires anaerobic culture on select media but its absence from standard MALDI-TOF databases complicates identification. Susceptibility data do not exist, so empiric treatment is the only option for this rare pathogen.

Immune microenvironment and lymph node yield in colorectal cancer.

BACKGROUND: Lymph node (LN) harvesting is associated with outcomes in colonic cancer. We sought to interrogate whether a distinctive immune milieu of the primary tumour is associated with LN yield. METHODS: A total of 926 treatment-naive patients with colorectal adenocarcinoma with more than 12 LNs (LN-high) were compared with patients with 12 or fewer LNs (LN-low). We performed immunohistochemistry and quantification on tissue microarrays for HLA class I/II proteins, beta-2-microglobulin (B2MG), CD8, CD163, LAG3, PD-L1, FoxP3, and BRAF V600E. RESULTS: The LN-high group was comprised of younger patients, longer resections, larger tumours, right-sided location, and tumours with deficient mismatch repair (dMMR). The tumour microenvironment showed higher CD8+ cells infiltration and B2MG expression on tumour cells in the LN-high group compared to the LN-low group. The estimated mean disease-specific survival was higher in the LN-high group than LN-low group. On multivariate analysis for prognosis, LN yield, CD8+ cells, extramural venous invasion, perineural invasion, and AJCC stage were independent prognostic factors. CONCLUSION: Our findings corroborate that higher LN yield is associated with a survival benefit. LN yield is associated with an immune high microenvironment, suggesting that tumour immune milieu influences the LN yield.

Apoptosis, Crypt Dropout, and Equivocal Immunohistochemical Staining May Indicate Cytomegalovirus Infection in Inflammatory Bowel Disease Patients.

Cytomegalovirus (CMV) colitis superimposed on inflammatory bowel disease (IBD) can be challenging to diagnose. This study aimed to determine what histologic clues and immunohistochemistry (IHC) utilization practices, if any, can help diagnose CMV superinfection in IBD. Colon biopsies were reviewed from all patients with CMV colitis with and without IBD between 2010 and 2021 at one institution, along with a separate cohort of IBD patients with negative CMV IHC. Biopsies were assessed for histologic features of activity and chronicity, phlebitis, fibrin thrombi, basal crypt apoptosis, CMV viral cytopathic effect (VCE), and CMV IHC positivity. Features between groups were compared, with statistical significance set at P -value <0.05. The study included 251 biopsies from 143 cases (21 CMV-only, 44 CMV+IBD, 78 IBD-only). Compared with the IBD-only group, the CMV+IBD group was more likely to show apoptotic bodies (83% vs. 64%, P =0.035) and crypt dropout (75% vs. 55%, P =0.045). CMV was detected by IHC in 18 CMV+IBD cases without VCE on hematoxylin and eosin (41%). In the 23 CMV+IBD cases where IHC was performed on all concurrent biopsies, IHC was positive in at least 1 biopsy in 22 cases. Six individual CMV+IBD biopsies with no VCE on hematoxylin and eosin demonstrated equivocal IHC staining. Of these, 5 had evidence of CMV infection. IBD patients with superimposed CMV infection are more likely to demonstrate apoptotic bodies and crypt dropout compared with their noninfected counterparts. Equivocal IHC staining for CMV may indicate true infection in IBD patients, and staining multiple biopsies from the same accession can improve CMV detection.

Clinical, pathological, genetics and intratumoural immune milieu of micropapillary carcinoma of the colon.

AIM: Micropapillary carcinoma (MPC) is a recognised WHO variant of colonic carcinoma (CC), although little is known about its prognosis, immune microenvironment and molecular alterations. We investigated its clinical, pathological and immunological characteristics. METHODS: We assessed 903 consecutive CCs and used the WHO definition to identify MPC. We recorded serrated and mucinous differentiation and mismatch repair (MMR) status. We performed immunohistochemistry and quantification on tissue microarrays for HLA class I/II proteins, beta-2-microglobulin (B2MG), CD8, CD163, LAG3, PD-L1, FoxP3, PD-L1and BRAF V600E. RESULTS: We classified 8.6% (N=78) of CC as MPC. Relative to non-MPC, MPC was more often high grade (p=0.03) and showed serrated morphology (p<0.01); however, we found no association with extramural venous invasion (p=0.41) and American Joint Committee on Cancer stage (p=0.95). MPCs showed lower numbers of CD8 positive lymphocytes (p<0.01), lower tumour cell B2MG expression (p=0.04) and lower tumour cell PD-L1 expression (p<0.01). There was no difference in HLA class I/II, LAG3, FOXP3, CD163 and PD-L1 positive histiocytes. There was no association with MMR status or BRAF V600E relative to non-MPC. MPC was not associated with decreased disease-specific survival (p=0.36). CONCLUSION: MPCs are associated with high-grade differentiation and a less active immune microenvironment than non-MPC. MPC is not associated with inferior disease-specific survival.

Can histologic features predict neoadjuvant therapy response in rectal adenocarcinoma?

Current standard therapy for locally advanced rectal cancer (LARC) is neoadjuvant therapy followed by surgical resection; however, treatment response is variable among patients. This study aimed to identify histologic features that predict tumor response. This retrospective study included 105 patients with LARC, all of whom underwent biopsy followed by neoadjuvant therapy and subsequent surgical resection. Each patient's initial biopsy was evaluated for tumor grade, tumor budding, intraepithelial lymphocytes, intraepithelial neutrophils, desmoplasia, apoptosis, adjacent stromal lymphocytes, signet ring cells, mucinous features, tumoral Paneth cells, dirty necrosis, microscopic ulceration, and prominent lymphoid aggregates. These histologic features, along with patient age at diagnosis and tumor microsatellite status, were compared to tumor regression grades from the respective resection specimens. No histologic factors in tumor biopsies predictive of treatment response in post-therapy resection specimens were identified. Histologic features in pre-therapy biopsy samples of LARC do not predict subsequent response to neoadjuvant therapy. Effective and reliable methods to predict response to neoadjuvant therapy in rectal cancer remain elusive.

From Mixed Hyperplastic/Adenomatous Polyp to Sessile Serrated Lesion: A Long and Winding Road for Long and Winding Crypts.

CONTEXT.­: During the past 3 decades, numerous articles in the literature have offered terminology, diagnostic criteria, and consensus recommendations regarding the entity currently referred to by the World Health Organization as sessile serrated lesion. Given the many names and various, variably reproducible diagnostic criteria ascribed to sessile serrated lesion, confusion persists for many pathologists and gastroenterologists regarding the diagnosis. This distinction is important, as sessile serrated lesion can progress to malignancy, unlike its main differential diagnosis, hyperplastic polyp. Research studies have shed light on the characteristic architecture and morphology, immunohistochemical patterns, and molecular alterations of sessile serrated lesion, and multiple consensus meetings around the globe have developed their criteria and nomenclature, often clashing or mixing terms. OBJECTIVE.­: To provide a narrative review from the entity's early description to our current understanding. DATA SOURCES.­: The existing scientific and clinical literature, published texts, medical society recommendations, and specialty consensus guidelines. CONCLUSIONS.­: The current World Health Organization criteria are a distillation of this scientific process, but terminology is still a point of contention worldwide.