Exploring thrombus composition in cerebral venous thrombosis: the first case report with initial insights and implications for treatment advancements

BACKGROUND

Endovascular thrombectomy (EVT) is a treatment option in patients with a cerebral venous thrombosis (CVT) who deteriorate despite anticoagulant treatment. Assessment of thrombus composition in CVT may provide insights into the pathophysiology of the disease and suggest new therapeutic strategies.

CASE REPORT

A 47-year-old woman (smoking habit and estradiol/progesterone-releasing intra-uterine device) diagnosed with massive CVT underwent EVT (complete recanalization via aspiration catheter and stentriever) due to acute-onset left-sided weakness and dysarthria despite 72 h of full-dose subcutaneous low-molecular heparin. Two main reddish clots (maximum diameter 15 mm) were retrieved. Microscopic assessment showed an erythrocyte-rich thrombus (83.9% of entire thrombus surface) with layers of platelets/fibrin (lines of Zahn: 13.9% fibrin and 38.5% platelet [CD61+]). The immunological profile was dominated by neutrophils (30% MPO+), with neutrophil extracellular traps (NETs) in 1.9% of thrombus surface. T- (CD3+), B-lymphocytes (CD20+), and monocytes/macrophages (CD68+) were rather rare (2.2%, 0.7%, and 2.0% respectively). We found no evidence (0.0%) of hemosiderin and endothelial cells (CD34+). Full clinical recovery occurred prior to discharge.

CONCLUSION

This is the first case report of a CVT with histologic assessment of the thrombus retrieved via EVT. Evaluating thrombi in CVT can provide key insights into disease pathophysiology and guide treatment advancements.

Intraluminal carotid thrombus leading to postpartum stroke: a case study

BACKGROUND

Intraluminal non-occlusive thrombus (ILT) is a rare cause of ischemic stroke. Although in most cases ILT is associated with arterial wall disorders, it has also been documented in patients with thrombophilic conditions.

CASE REPORT

We present a case of carotid ILT in a 38-year-old puerperal woman with pregnancy-induced hypercoagulability. Following in vitro fertilization pregnancy, she experienced acute left-sided weakness 9 days after delivery. CT angiography revealed an intraluminal filling defect in the right carotid bulb, suggestive of a thrombus, along with ipsilateral MCA sub-occlusion. Mechanical thrombectomy was performed, achieving complete vessel recanalization without any endovascular intervention on the carotid ILT. Comprehensive evaluation excluded any underlying carotid vessel wall disease (such as atherosclerosis, inflammatory diseases, arterial dissection, focal dysplasia), inherited or acquired thrombophilia, and the sole prothrombotic risk factor identified was the puerperium. Histological thrombus analysis showed fibrin/platelet-rich material with significant macrophage infiltration (consistent with an intermediate/organized thrombus, suggesting potential embolization from a pre-existing carotid ILT). Anti-thrombotic treatment (acetylsalicylic acid 100 mg and enoxaparin 6000 UI) resulted in complete thrombus resolution at follow-up.

CONCLUSION

ILT should be considered a potential case of embolic stroke in pregnancy or puerperium. Vessel imaging is essential for diagnosis. Histological thrombus analysis can provide insights into the pathophysiological mechanisms of stroke.

Tolerance to colibactin correlates with homologous recombination proficiency and resistance to irinotecan in colorectal cancer cells

The bacterial genotoxin colibactin promotes colorectal cancer (CRC) tumorigenesis, but systematic assessment of its impact on DNA repair is lacking, and its effect on response to DNA-damaging chemotherapeutics is unknown. We find that CRC cell lines display differential response to colibactin on the basis of homologous recombination (HR) proficiency. Sensitivity to colibactin is induced by inhibition of ATM, which regulates DNA double-strand break repair, and blunted by HR reconstitution. Conversely, CRC cells chronically infected with colibactin develop a tolerant phenotype characterized by restored HR activity. Notably, sensitivity to colibactin correlates with response to irinotecan active metabolite SN38, in both cell lines and patient-derived organoids. Moreover, CRC cells that acquire colibactin tolerance develop cross-resistance to SN38, and a trend toward poorer response to irinotecan is observed in a retrospective cohort of CRCs harboring colibactin genomic island. Our results shed insight into colibactin activity and provide translational evidence on its chemoresistance-promoting role in CRC.

DOG1 expression in neuroendocrine neoplasms: Potential applications and diagnostic pitfalls

Neuroendocrine neoplasms represent a heterogeneous group of rare tumors, more frequently arising from gastroenteropancreatic tract and lungs. At the time of diagnosis, 20% of cases are metastatic, and 10% of cases are considered as cancer of unknown primary origin. Several immunohistochemical markers are routinely used to confirm the neuroendocrine differentiation, first among all Synaptophysin and Chromogranin-A; on the other hand, different immunohistochemical markers are used to establish primary anatomical site, as TTF1, CDX2, Islet-1 and Calcitonin, but no marker is available in order to distinguish among different sites of the digestive tract. DOG1 (discovered on GIST-1) is a gene normally expressed in interstitial cells of Cajal and, in routine practice, DOG1 immunostaining is used in diagnosis of GIST (gastrointestinal stromal tumor). DOG1 expression has been described in several neoplasms other than GIST, both in mesenchymal and epithelial neoplasms. In the present study, DOG1 immunostaining has been performed in a large cohort of neuroendocrine neoplasms, including neuroendocrine tumors and neuroendocrine carcinomas, in order to evaluate frequency, intensity and pattern of expression in different anatomical site and in different tumor grade. DOG1 expression was detected in a large percentage of neuroendocrine tumors, with statistically significant association between DOG1 expression and gastrointestinal tract neuroendocrine tumors. As a consequence, DOG1 could be included in marker panel for the identification of primary site in neuroendocrine metastases of unknown primary origin; moreover, these results recommend careful evaluation of DOG1 expression in gastrointestinal neoplasms, in particular in differential diagnosis between epithelioid GIST and neuroendocrine tumors.

The Day-To-Day Practice of MMR and MSI Assessment in Colorectal Adenocarcinoma: What We Know and What We Still Need to Explore

BACKGROUND

The DNA mismatch repair (MMR) system is a highly preserved protein complex recognizing short insertions, short deletions, and single base mismatches during DNA replication and recombination. MMR protein status is identified using immunohistochemistry. Deficit in one or more MMR proteins, configuring deficient MMR status (dMMR), leads to frameshift mutations particularly clustered in microsatellite repeats. Thus, microsatellite instability (MSI) is the epiphenomenon of dMMR. In colorectal cancer (CRC), MMR/MSI status is a biomarker with prognostic and predictive value of resistance to 5-fluorouracil and response to immune checkpoint inhibitor therapy.

SUMMARY

In this Review, we describe the challenges the practicing pathologist may face in relation to the assessment of MMR/MSI status and any open issues which still need to be addressed, focusing on pre-analytic issues, pitfalls in the interpretation, and technical aspects of the different assays.

KEY MESSAGES

The current methods of detecting dMMR/MSI status have been optimized for CRCs, and whether these techniques can be applied to all tumor and specimen types is still not fully understood. Following the Food and Drug Administration (FDA), tissue/site agnostic drug approval of pembrolizumab for advanced/metastatic MSI tumors, MMR/MSI status in gastrointestinal tract is a common request from the oncologist. In this setting, several issues still need to be addressed, including criteria for sample adequacy.

Multimodal treatment with curative intent in a germline BRCA2 mutant metastatic ampullary adenocarcinoma: a case report

BACKGROUND

Cancers of the Vater ampulla (ampullary cancers, ACs) account for less than 1% of all gastrointestinal tumors. ACs are usually diagnosed at advanced stage, with poor prognosis and limited therapeutic options. BRCA2 mutations are identified in up to 14% of ACs and, differently from other tumor types, therapeutic implications remain to be defined. Here, we report a clinical case of a metastatic AC patient in which the identification of a BRCA2 germline mutation drove a personalized multimodal approach with curative-intent.

CASE PRESENTATION

A 42-year-old woman diagnosed with stage IV BRCA2 germline mutant AC underwent platinum-based first line treatment achieving major tumor response but also life-threatening toxicity. Based on this, as well as on molecular findings and expected low impact of available systemic treatment options, the patient underwent radical complete surgical resection of both primary tumor and metastatic lesions. Following an isolated retroperitoneal nodal recurrence, given the expected enhanced sensitivity to radiotherapy in BRCA2 mutant cancers, the patient underwent imaging-guided radiotherapy leading to long-lasting complete tumor remission. After more than 2 years, the disease remains radiologically and biochemically undetectable. The patient accessed a dedicated screening program for BRCA2 germline mutation carriers and underwent prophylactic bilateral oophorectomy.

CONCLUSIONS

Even considering the intrinsic limitations of a single clinical report, we suggest that the finding of BRCA germline mutations in ACs should be taken into consideration, together with other clinical variables, given their potential association with remarkable response to cytotoxic chemotherapy that might be burdened with enhanced toxicity. Accordingly, BRCA1/2 mutations might offer the opportunity of personalizing treatment beyond PARP inhibitors up to the choice of a multimodal approach with curative-intent.

Unique Patterns of Heterogeneous Mismatch Repair Protein Expression in Colorectal Cancer Unveil Different Degrees of Tumor Mutational Burden and Distinct Tumor Microenvironment Features

Mismatch repair (MMR) protein expression in colorectal cancer (CRC) cells is usually homogeneously retained or lost. Rare lesions may show a heterogeneous pattern of MMR protein expression. We evaluated MMR protein expression (MLH1, MSH2, MSH6, and PMS2) in 200 CRCs, identifying 3 groups with proficient MMR protein expression (MMRp), deficient MMR protein expression (MMRd), and heterogeneous MMR protein expression (MMRh). MMRh tumors were microdissected on the basis of the expression of the heterogeneous marker. DNA was extracted and subjected to targeted sequencing. RNA was purified from bulk tumors of all MMRh cases and in a control series of 15 MMRp and 10 MMRd CRCs and analyzed using the PanCancer IO 360 Panel (NanoString Technologies). Twenty-nine of the 200 cases (14.5%) were MMRd. Nine cases (4.5%) showed a heterogeneous pattern of MMR expression, with 6 tumors harboring concomitant loss of one of the other MMR proteins, thus featuring areas with double loss at immunohistochemistry (IHC) testing (MMRh double-loss cases). Four of the 6 MMRh double-loss cases were suitable for a separate sequence variant analysis of IHC double-negative and IHC single-negative components of the tumor. In all lesions, both components exhibited a high tumor mutation burden (TMB). Nevertheless, a significant increase in TMB in the double-negative components was observed (mean TMB: negative, 70 mut/Mb vs positive, 59 mut/Mb) because of a higher number of subclonal variants compared with the other component. Comparative gene expression analyses among MMRd, MMRp, and MMRh CRCs highlighted differential gene expression patterns and an increased number of tumor-infiltrating lymphocytes in MMRh lesions, which is also characterized by a substantial population of exhausted CD8⁺ lymphocytes. We describe a unique subgroup of CRCs showing heterogeneous expression of MMR proteins in a background of concomitant loss of one of the other markers.

Genetic and pharmacological modulation of DNA mismatch repair heterogeneous tumors promotes immune surveillance

Patients affected by colorectal cancer (CRC) with DNA mismatch repair deficiency (MMRd), often respond to immune checkpoint blockade therapies, while those with mismatch repair-proficient (MMRp) tumors generally do not. Interestingly, a subset of MMRp CRCs contains variable fractions of MMRd cells, but it is unknown how their presence impacts immune surveillance. We asked whether modulation of the MMRd fraction in MMR heterogeneous tumors acts as an endogenous cancer vaccine by promoting immune surveillance. To test this hypothesis, we use isogenic MMRp (Mlh1^+/+) and MMRd (Mlh1^-/-) mouse CRC cells. MMRp/MMRd cells mixed at different ratios are injected in immunocompetent mice and tumor rejection is observed when at least 50% of cells are MMRd. To enrich the MMRd fraction, MMRp/MMRd tumors are treated with 6-thioguanine, which leads to tumor rejection. These results suggest that genetic and pharmacological modulation of the DNA mismatch repair machinery potentiate the immunogenicity of MMR heterogeneous tumors.

Abstract 5419: A unique pattern of heterogeneous MMR protein expression in colorectal cancer unveils different degrees of tumor mutational burden and distinct tumor microenvironment features

Introduction: Mismatch repair (MMR) protein expression in colorectal cancer (CRC) is usually homogeneously retained or lost. However, rare CRC lesions may show a heterogeneous pattern of MMR protein expression. We aimed to evaluate the molecular effect of a heterogeneous expression of the MMR proteins in a complex context of concomitant loss of one of the other effectors of the DNA repair mechanism.

Experimental procedures: We evaluated MMR protein expression (by immunohistochemistry -IHC- for MLH1, MSH2, MSH6 and PMS2) in 200 CRCs, identifying 3 groups with proficient (MMRp), deficient (MMRd) and heterogeneous (MMRh) MMR. MMRh tumors were micro-dissected based on the expression of the heterogeneous marker, DNA was extracted and subjected to targeted sequencing (TSO500 panel, Illumina). RNA was purified from bulk tumors of all MMRh cases and in a control series of 10 MMRp and 10 MMRd CRCs and analyzed using the IO360 panel (NanoString). The degree of tumor infiltrating lymphocytes (TILs) was calculated on H&E slides and on IHC sections stained with antibodies raised against CD8.

Results: Twenty-nine out of 200 cases were MMRd (14.5%). Nine cases (4.5%) showed a heterogeneous pattern of MMR expression, with 6 tumors harboring concomitant loss of one of the other MMR proteins, resulting in a microsatellite instable (MSI) phenotype. Five out of the 9 cases were suitable for separate mutational analysis of IHC-positive and IHC-(double)negative components of the tumor. Both components of all the lesions exhibited a high tumor mutation burden (mean TMB: 59 mut/Mb) in line with the MSI status, nevertheless a significant increase in TMB in the double-negative components was observed (mean TMB: neg. 67 mut/Mb vs pos. 53 mut/Mb), due to a higher number of sub-clonal, non-synonymous variants compared to the positive component. Comparative gene expression analyses between MMRd, MMRp and MMRh CRCs highlighted differential gene expression patterns, with MMRh tumors displaying a strong activation of angiogenesis, MAPK and PI3K-AKT axes. Moreover, these tumors showed the highest number of TILs, characterized by a substantial population of exhausted CD8+ lymphocytes.

Conclusions: We describe a unique subgroup of CRCs showing heterogeneous expression of MMR proteins, in a background of concomitant loss of one of the other markers. This heterogeneity is associated with i) an increase of TMB and of unstable loci in the negative component, with additional markedly sub-clonal variants, ii) a high number of TILs, mostly exhausted CD8+ lymphocytes, and iii) a differential activation of signaling pathways. Taken together these data provide indirect evidence that heterogeneous loss of MMR proteins may impact on the biology of CRCs. Whether this pattern may influence response to immune checkpoint inhibition remains to be determined.

Citation Format: Enrico Berrino, Maria Costanza Aquilano, Emanuele Valtorta, Vito Amodio, Giovanni Germano, Marco Gusmini, Ivana Sarotto, Anna Sapino, Silvia Marsoni, Andrea Sartore-Bianchi, Alberto Bardelli, Salvatore Siena, Emanuela Bonoldi, Caterina Marchio. A unique pattern of heterogeneous MMR protein expression in colorectal cancer unveils different degrees of tumor mutational burden and distinct tumor microenvironment features [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 5419.

Histopathology of IBD Colitis. A practical approach from the pathologists of the Italian Group for the study of the gastrointestinal tract (GIPAD)

Inflammatory bowel diseases (IBDs) are lifelong disorders in which an interaction between genetic and environmental factors is involved. IBDs include two entities: Crohn's disease (CD) and ulcerative colitis (UC); these can be adequately diagnosed and distinguished with a correct methodological approach based on communicating exhaustive clinical, endoscopic and laboratory information to the pathologist and performing adequate bioptic sampling and precise morphological signs including crypt architecture, distribution of inflammation and granulomas, when present. IBD needs to be distinguished from non-IBD colitis, mostly at its onset. Moreover, IBDs are associated with an increased risk of developing colorectal adenocarcinoma. In daily pathological practice, correct diagnosis of IBD and its subclassification as well as a correct detection of dysplasia is imperative to establish the best therapeutic approach.

Prognostic value of pathological tumor regression grade in locally advanced gastric cancer: New perspectives from a single-center experience

BACKGROUND AND OBJECTIVE

Perioperative chemotherapy (PC) with radical surgery represents the gold standard of treatment for resectable advanced gastric cancer (GC). The prognostic value of pathological tumor regression grade (TRG) induced by neoadjuvant chemotherapy (NACT) is not clearly established. This study aimed to investigate the correlation between TRG and survival in GC.

METHODS

Patients affected by advanced GC undergoing PC and radical surgery were considered. TRG was assessed for each patient according to Becker's grading system. The correlation between TRG and survival was investigated.

RESULTS

One-hundred patients were selected; 25 showed a good response (GR) (TRG 1a/1b), while 75 had a poor response (PR) (TRG 2/3) to NACT. GR patients showed better disease-free survival (DFS) (52 vs. 19 months, p < .001) and disease-specific survival (DSS) (57 vs. 25 months, p < .0001) when compared to PR patients. On univariate analysis, TRG, lymph node ratio (LNR), tumor size, grading, and post-neoadjuvant therapy TNM stage were significantly correlated with survival. On multivariate analysis, TRG, LNR and tumor size were independent prognostic factors for DFS and DSS.

CONCLUSIONS

TRG, LNR, and tumor size are independent prognostic factors for DFS and DSS in patients with advanced GC undergoing NACT.

Synergy of cytological methods in the pathological staging of breast cancer: Axillary fine-needle aspiration and intraoperative scrape cytology of the sentinel lymph node

BACKGROUND

Sentinel lymph node biopsy (SLNB) has become the standard in breast cancer staging, but it is costly and time-consuming. Fine-needle aspiration cytology (FNAC) under ultrasonographic guidance identifies patients who need axillary lymph-node dissection (ALND), thus reducing costs. As an alternative to frozen sections (FS), intraoperative scrape cytology (ISC) for SLNB is an inexpensive, rapid, accurate and safe technique. We evaluated the synergy of FNAC and SLNB in determining the axillary burden and the performance of the ISC method.

METHODS

Over a nine-year period, 894 breast cancer patients were analyzed. Of these, 439 patients with echographic suspicious nodes underwent preoperative FNAC; negative axillary ultrasounds or FNACs resulted in 606 intraoperative SLNB, performed using the ISC technique. The results were compared with histological diagnosis, and sensitivity, specificity, predictive values and accuracy were calculated.

RESULTS

Of the 439 FNACs, 121 were positive and underwent immediate ALND, and 242 negative patients underwent intraoperative SLNB (69% sensitivity, 99% specificity). Positive cases often had multiple nodal involvement (55% pN2-3). Of the 606 SLNB-ISC smears, 510 were true negative; 65 true positives allowed for one-step ALND (71% sensitivity, 99% specificity).

CONCLUSION

Preoperative positive axillary FNAC predicts a higher disease burden and determines the avoidance of SLNB for patients eligible for immediate ALND. ISC instead of FS is a safe and sensitive technique to identify metastases, indicating completion of ALND.

PARTIALLY PRESENTED AT

Joint International Oncology (sentinel node & cancer metastasis) Congress, May 27-29, 2013, San Francisco, California, USA 18 ° International Congress of Cytology (ICC 2013-1161), May 26-30, 2013, Paris, France Convegno Nazionale GISMa - Finalborgo (Savona), Italy,19-20 maggio 2016.

Gastrointestinal stromal tumors: usefulness of immunohistochemistry, flow cytometry and fluorescence in situ hybridization

BACKGROUND AND AIMS

Gastrointestinal stromal tumors (GIST) constitute a group of primary mesenchymal tumors of the gastrointestinal tract, known for their diversity in clinical behavior and the difficulties in determining malignancy and prognosis. This retrospective study evaluated a series of GIST by means of immunohistochemical techniques, flow cytometry and fluorescence in situ hybridization (FISH).

METHODS

Nine patients with GIST were analyzed for tumor size, mitotic count and CD117, CD34, MIB-1 with immunohistochemistry. In addition, the GIST were tested with FISH for chromosomes 8 and 17 and DNA index was evaluated by flow cytometry.

RESULTS

The findings confirmed the usefulness of CD117 and CD34 in diagnosing GIST and the prognostic role of MIB-1, but do not support a correlation between aneuploidy in flow cytometry and poor outcome. The FISH results suggest close follow-up for patients with benign GIST with a numerical alteration of chromosome 8. The technique could select patients with tumors at high-risk with aneusomy of chromosome 17.

CONCLUSION

This study shows the possible application of FISH to the evaluation of patients with GIST, in addition to analysis of morphological features.

Merkel cell carcinoma and HIV infection: a case report and review of the literature

Merkel cell carcinoma (MCC) is a skin cancer of neuroendocrine origin that occurs most often in sun-exposed areas. In the general population, it is a disease of older adults, with only 5% of cases occurring below the age of 50 years. Immunosuppression is the significant risk factor for the development of MCC and recently it was suggested that individuals with HIV have a relative risk of 13.4 to developed MCC in comparison with the general population. We report a case of MCC in an HIV-infected patient and we review nine patients with HIV with MCC. Our patient was a 54-year-old man who came to our attention without a known HIV diagnosis. He was apparently in good health and had no risk factor for HIV, but by the atypical site of the lesion and by the relative young age of the patient we suspected a case of immunosuppression and for this reason we did HIV test that had a positive result. The patient was treated with surgery and chemotherapy but died as a result of liver metastases 25 months after his tumor was diagnosed.

Colonic amoebiasis and spirochetosis: morphological, ultrastructural and microbiological evaluation

BACKGROUND

The present study reports on a prompt diagnosis of colonic amoebiasis with colonic spirochetosis by Brachyspira aalborgi and B. pilosicoli; such diagnosis allowed exclusion of other diseases and resolution of the case after specific treatment.

METHODS AND RESULTS

A 37-year-old Italian man with a history of several months' mucosal diarrhea travelled to Greece, Romania and Tunisia. After his last trip he presented with an increase of up to 3-5 discharges daily, associated with bloody diarrhea, supporting the clinical suspect of inflammatory bowel disease. Colonoscopy revealed erosions from the cecum to the rectum, and ulcers both in the descending and sigmoid colon. Structures resembling amoebic trophozoites and sinusoidal microorganisms were observed in the colonic biopsies at histopathology and electron microscopy. Entamoeba histolytica DNA was detected by small-subunit rDNA polymerase chain reaction (PCR) from feces, rectal biopsies and isolated trophozoites. Spirochetes were identified from feces, colonic biopsies and cultures using a 16S rDNA restriction fragment length polymorphism-PCR specific for the detection of B. aalborgi and B. pilosicoli. After therapy, the patient was restored to health.

CONCLUSIONS

The rapid identification of E. histolytica, B. aalborgi and B. pilosicoli using traditional and specific and sensitive molecular methods permitted an accurate diagnosis and a specific therapy. It is suggested that mixed infection by parasites and spirochetes might occur more frequently than expected: it would be of extreme interest and importance to intensify clinical findings, and one infection should not prompt the pathologist/clinician to stop looking.