Integrating AI-Powered Digital Pathology and Imaging Mass Cytometry Identifies Key Classifiers of Tumor Cells, Stroma, and Immune Cells in Non-Small Cell Lung Cancer.

Artificial intelligence (AI)-powered approaches are becoming increasingly used as histopathologic tools to extract subvisual features and improve diagnostic workflows. On the other hand, hi-plex approaches are widely adopted to analyze the immune ecosystem in tumor specimens. Here, we aimed at combining AI-aided histopathology and imaging mass cytometry (IMC) to analyze the ecosystem of non-small cell lung cancer (NSCLC). An AI-based approach was used on hematoxylin and eosin (H&E) sections from 158 NSCLC specimens to accurately identify tumor cells, both adenocarcinoma and squamous carcinoma cells, and to generate a classifier of tumor cell spatial clustering. Consecutive tissue sections were stained with metal-labeled antibodies and processed through the IMC workflow, allowing quantitative detection of 24 markers related to tumor cells, tissue architecture, CD45+ myeloid and lymphoid cells, and immune activation. IMC identified 11 macrophage clusters that mainly localized in the stroma, except for S100A8+ cells, which infiltrated tumor nests. T cells were preferentially localized in peritumor areas or in tumor nests, the latter being associated with better prognosis, and they were more abundant in highly clustered tumors. Integrated tumor and immune classifiers were validated as prognostic on whole slides. In conclusion, integration of AI-powered H&E and multiparametric IMC allows investigation of spatial patterns and reveals tissue relevant features with clinical relevance. SIGNIFICANCE: Leveraging artificial intelligence-powered H&E analysis integrated with hi-plex imaging mass cytometry provides insights into the tumor ecosystem and can translate tumor features into classifiers to predict prognosis, genotype, and therapy response.

Important functional role of the protein osteopontin in the progression of malignant pleural mesothelioma.

Background: Malignant Pleural Mesothelioma (MPM) is an aggressive cancer of the mesothelial lining associated with exposure to airborne non-degradable asbestos fibers. Its poor response to currently available treatments prompted us to explore the biological mechanisms involved in its progression. MPM is characterized by chronic non-resolving inflammation; in this study we investigated which inflammatory mediators are mostly expressed in biological tumor samples from MPM patients, with a focus on inflammatory cytokines, chemokines and matrix components. Methods: Expression and quantification of Osteopontin (OPN) was detected in tumor and plasma samples of MPM patients by mRNA, immunohistochemistry and ELISA. The functional role of OPN was investigated in mouse MPM cell lines in vivo using an orthotopic syngeneic mouse model. Results: In patients with MPM, the protein OPN was significantly more expressed in tumors than in normal pleural tissues and predominantly produced by mesothelioma cells; plasma levels were elevated in patients and associated with poor prognosis. However, modulation of OPN levels was not significantly different in a series of 18 MPM patients receiving immunotherapy with durvalumab alone or with pembrolizumab in combination with chemotherapy, some of whom achieved a partial clinical response. Two established murine mesothelioma cell lines: AB1 and AB22 of sarcomatoid and epithelioid histology, respectively, spontaneously produced high levels of OPN. Silencing of the OPN gene (Spp1) dramatically inhibited tumor growth in vivo in an orthotopic model, indicating that OPN has an important promoting role in the proliferation of MPM cells. Treatment of mice with anti-CD44 mAb, blocking a major OPN receptor, significantly reduced tumor growth in vivo. Conclusion: These results demonstrate that OPN is an endogenous growth factor for mesothelial cells and inhibition of its signaling may be helpful to restrain tumor progression in vivo. These findings have translational potential to improve the therapeutic response of human MPM.

Association of IgG4-related disease and systemic rheumatic disorders.

PURPOSE: Autoimmune disorders can occur together especially in genetically predisposed individuals. We here aimed to assess the occurrence of IgG4-related disease (IgG4-RD) in association with other systemic immune-mediated conditions. METHODS: We retrospectively analyzed the clinical records of patients with IgG4-RD followed at the IgG4-RD Clinic of San Raffaele Hospital (Milan, Italy) for pre-existing or concomitant immune-mediated disorders. IgG4-RD was diagnosed based on histological findings and on the 2011 Comprehensive Diagnostic criteria. Associated immune-mediated disorders were diagnosed based on available classification and/or diagnostic criteria. RESULTS: Two-hundred and thirty-four patients with a definitive diagnosis of IgG4-RD were included in this study. A pre-existing immune-mediated connective tissue disease was reported in 6/234 patients (3%): one case each of sarcoidosis, Takayasu arteritis (TA), eosinophilic granulomatosis with polyangitis (EGPA), and rheumatoid arthritis; and two cases of granulomatosis with polyangitis (GPA). Organs involved by IgG4-RD included the lungs, the pancreas, the peritoneum, lacrimal glands, meninges and orbits. Sarcoidosis, EGPA, and TA preceded the onset of IgG4-RD. GPA preceded IgG4-RD onset in one case and occurred simultaneously in the other case. Rheumatoid arthritis occurred together with IgG4-RD in one case. CONCLUSION: Our observation suggests that "secondary" IgG4-RD can present in the context of pre-existing systemic immune-mediated disorders and complicate systemic autoimmune diseases as well as chronic granulomatous conditions. Further studies are needed to define whether this peculiar clinical scenario is associated with different genetic backgrounds, pathological bases, and long-term outcomes.

Exon-18-EGFR Mutated Transformed Small-Cell Lung Cancer: A Case Report and Literature Review.

Small-cell lung cancer (SCLC) transformation from EGFR mutant adenocarcinoma is a rare entity that is considered to be a new phenotype of SCLC. While transformation from adenocarcinoma (ADC) with EGFR exon 19 deletions and exon 21 L858R point mutations has been described, to our knowledge, no cases of transformation to SCLC from exon-18-mutated ADC have been reported. We reported a clinical case of a patient with exon-18-EGFR-transformed SCLC, and we performed a systematic review of the literature.

Diagnostic accuracy and safety of EUS-guided end-cutting fine-needle biopsy needles for tissue sampling of abdominal and mediastinal lymphadenopathies: a prospective multicenter series.

BACKGROUND AND AIMS: The role of the newer EUS fine-needle biopsy needles in lymphadenopathies (LAs) is still under evaluation. We aimed to evaluate the diagnostic accuracy and adverse event rate of EUS-guided fine-needle biopsy sampling (EUS-FNB) in diagnosing LAs. METHODS: From June 2015 to June 2022, all patients referred to 4 institutions for EUS-FNB of mediastinal and abdominal LAs were enrolled. Twenty-two-gauge Franseen tip or 25-gauge fork-tip needles were used. The criterion standard for positive results was surgery or imaging and clinical evolution over a follow-up of at least 1 year. RESULTS: One hundred consecutive patients were enrolled, consisting of those with a new diagnosis of LA (40%), presence of LA with a previous history of neoplasia (51%), or suspected lymphoproliferative disease (9%). EUS-FNB was technically feasible in all LA patients with 2 to 3 passes (mean, 2.62 ± .93). The overall sensitivity, positive predictive value, specificity, negative predictive value, and accuracy for EUS-FNB were 96.20%, 100%, 100%, 87.50%, and 97.00%, respectively. Histologic analysis was feasible in 89% of cases. Cytologic evaluation was performed in 67% of specimens. A statistical difference between the accuracy of the 22-gauge or 25-gauge needle (P = .63) was not found. A subanalysis on lymphoproliferative disease revealed a sensitivity and accuracy of 89.29% and 90.0%, respectively. No adverse events were recorded. CONCLUSIONS: EUS-FNB with new end-cutting needles is a valuable and safe method to diagnose LAs. The high quality of histologic cores and the good amount of tissue allowed a complete immunohistochemical analysis of metastatic LAs and precise subtyping of the lymphomas. (Clinical trial registration number: NCT02855151.).

Prognostic Factors across Poorly Differentiated Neuroendocrine Neoplasms: A Pooled Analysis.

INTRODUCTION: Poorly differentiated neuroendocrine carcinomas (NECs) are characterized by aggressive clinical course and poor prognosis. No reliable prognostic markers have been validated to date; thus, the definition of a specific NEC prognostic algorithm represents a clinical need. This study aimed to analyze a large NEC case series to validate the specific prognostic factors identified in previous studies on gastro-entero-pancreatic and lung NECs and to assess if further prognostic parameters can be isolated. METHODS: A pooled analysis of four NEC retrospective studies was performed to evaluate the prognostic role of Ki-67 cut-off, the overall survival (OS) according to primary cancer site, and further prognostic parameters using multivariable Cox proportional hazards model and machine learning random survival forest (RSF). RESULTS: 422 NECs were analyzed. The most represented tumor site was the colorectum (n = 156, 37%), followed by the lungs (n = 111, 26%), gastroesophageal site (n = 83, 20%; 66 gastric, 79%) and pancreas (n = 42, 10%). The Ki-67 index was the most relevant predictor, followed by morphology (pure or mixed/combined NECs), stage, and site. The predicted RSF response for survival at 1, 2, or 3 years showed decreasing survival with increasing Ki-67, pure NEC morphology, stage III-IV, and colorectal NEC disease. Patients with Ki-67 <55% and mixed/combined morphology had better survival than those with pure morphology. Morphology pure or mixed/combined became irrelevant in NEC survival when Ki-67 was ≥55%. The prognosis of metastatic patients who did not receive any treatment tended to be worse compared to that of the treated group. The prognostic impact of Rb1 immunolabeling appears to be limited when multiple risk factors are simultaneously assessed. CONCLUSION: The most effective parameters to predict OS for NEC patients could be Ki-67, pure or mixed/combined morphology, stage, and site.

Combined Large Cell Neuroendocrine Carcinomas of the Lung: Integrative Molecular Analysis Identifies Subtypes with Potential Therapeutic Implications.

BACKGROUND: Combined large cell neuroendocrine carcinoma (CoLCNEC) is given by the association of LCNEC with adeno or squamous or any non-neuroendocrine carcinoma. Molecular bases of CoLCNEC pathogenesis are scant and no standardized therapies are defined. METHODS: 44 CoLCNECs: 26 with adenocarcinoma (CoADC), 7 with squamous cell carcinoma (CoSQC), 3 with small cell carcinoma (CoSCLC), 4 with atypical carcinoid (CoAC) and 4 napsin-A positive LCNEC (NapA+), were assessed for alterations in 409 genes and transcriptomic profiling of 20,815 genes. RESULTS: Genes altered included TP53 (n = 30), RB1 (n = 14) and KRAS (n = 13). Targetable alterations included six KRAS G12C mutations and ALK-EML4 fusion gene. Comparison of CoLCNEC transcriptomes with 86 lung cancers of pure histology (8 AC, 19 ADC, 19 LCNEC, 11 SCLC and 29 SQC) identified CoLCNEC as a separate entity of neuroendocrine tumours with three different molecular profiles, two of which showed a non-neuroendocrine lineage. Hypomethylation, activation of MAPK signalling and association to immunotherapy signature specifically characterized each of three CoLCNEC molecular clusters. Prognostic stratification was also provided. CONCLUSIONS: CoLCNECs are an independent histologic category. Our findings support the extension of routine evaluation of KRAS mutations, fusion genes and immune-related markers to offer new perspectives in the therapeutic management of CoLCNEC.

Tumor-associated macrophages and risk of recurrence in stage III colorectal cancer.

Tumor-associated macrophages (TAMs) have a unique favorable effect on the prognosis of colorectal cancer (CRC), although their association with stage-specific outcomes remains unclear. We assessed the densities of CD68+ and CD163+ TAMs at the invasive front of resected CRC stage III CRC from 236 patients, 165 of whom received post-surgical FOLFOX treatment, and their relationship with disease-free survival (DFS). Associations between macrophage mRNAs and clinical outcome were investigated in silico in 59 stage III CRC and FOLFOX-treated patients from The Cancer Genome Atlas (TCGA). Biological interactions of SW480 and HT29 cells and macrophages with FOLFOX were tested in co-culture models. Low TAM densities were associated with shorter DFS among patients receiving FOLFOX (CD68+ , p = 0.0001; CD163+ , p = 0.0008) but not among those who were untreated. By multivariate Cox analysis, only low TAM (CD68+ , p = 0.001; CD163+ , p = 0.002) and nodal status (CD68+ , p = 0.009; CD163+ , p = 0.007) maintained an independent predictive value. In the TCGA cohort, high CD68 mRNA levels were associated with better outcome (p = 0.02). Macrophages enhanced FOLFOX cytotoxicity on CRC cells (p < 0.01), and drugs oriented macrophage polarization from M2- to M1-phenotype. Low TAM densities identify stage III CRC patients at higher risk of recurrence after adjuvant therapy, and macrophages can augment the chemo-sensitivity of micro-metastases.

Coexpression of ΔNp63/p40 and TTF1 Within Most of the Same Individual Cells Identifies Life-Threatening NSCLC Featuring Squamous and Glandular Biphenotypic Differentiation: Clinicopathologic Correlations.

Introduction: Double occurrence of TTF1 and ΔNp63/p40 (henceforth, p40) within the same individual cells is exceedingly rare in lung cancer. Little is known on their biological and clinical implications. Methods: Two index cases immunoreactive for both p40 and TTF1 and nine tumors selected from The Cancer Genome Atlas (TCGA) according to the mRNA levels of the two relevant genes entered the study. Results: The two index cases were peripherally located, poorly differentiated, and behaviorally unfavorable carcinomas, which shared widespread p40 and TTF1 decoration within the same individual tumor cells. They also retained SMARCA2 and SMARCA4 expression, while variably stained for p53, cytokeratin 5, and programmed death-ligand 1. A subset of basal cells p40+/TTF1+ could be found in normal distal airways. Biphenotypic glandular and squamous differentiation was unveiled by electron microscopy, along with EGFR, RAD51B, CCND3, or NF1 mutations and IGF1R, MYC, CCND1, or CDK2 copy number variations on next-generation sequencing analysis. The nine tumors from TCGA (0.88% of 1018 tumors) shared the same poor prognosis, clinical presentation, and challenging histology and had activated pathways of enhanced angiogenesis and epithelial-mesenchymal transition. Mutation and copy number variation profiles did not differ from the other TCGA tumors. Conclusions: Double p40+/TTF1+ lung carcinomas are aggressive and likely underrecognized non-small cell carcinomas, whose origin could reside in double-positive distal airway stem-like basal cells through either de novo-basal-like or differentiating cell mechanisms according to a model of epithelial renewal.

Locally advanced primary mediastinal atypical carcinoid successfully resected after neoadjuvant treatment: A case report.

Neuroendocrine tumors (NETs) are epithelial neoplasms with predominant neuroendocrine differentiation that arise in most organs of the body. Mediastinal NETs are very rare, and account for no more than 5% of all mediastinal tumors. R0 surgery represents the milestone of treatment. Here, we describe a case of a locally advanced primary atypical carcinoid of the mediastinum. This was initially considered inoperable due to infiltration of a great vessel and was successfully resected after neoadjuvant treatment as a result of very extensive surgery. Only through an accurate preoperative diagnosis and good radiological planning is it possible to obtain satisfactory oncological results.

Tracheal polypoid combined small cell lung cancer (C-SCLC): A case report.

Small cell lung cancer (SCLC) is an aggressive malignancy with a poor prognosis that accounts for 10% of all cases of clinical lung cancer. Due to its high growth fraction and rapid doubling time it is usually diagnosed as extensive local or metastatic disease in 60%-70% of cases. Combined small cell lung cancer (C-SCLC) is a relatively rare subtype of SCLC and is defined as SCLC combined with any elements of non-small cell lung cancer (NSCLC). Clinical presentation of SCLC as an isolated pedunculated endotracheal lesion is an especially rare occurrence. Here, we report for the first time the occurrence of a C-SCLC as a polypoid tumor of the trachea diagnosed in an 80-year-old woman admitted to the emergency department with a principal complaint of cough and wheezing.

Digital Pathology During the COVID-19 Outbreak in Italy: Survey Study.

BACKGROUND: Transition to digital pathology usually takes months or years to be completed. We were familiarizing ourselves with digital pathology solutions at the time when the COVID-19 outbreak forced us to embark on an abrupt transition to digital pathology. OBJECTIVE: The aim of this study was to quantitatively describe how the abrupt transition to digital pathology might affect the quality of diagnoses, model possible causes by probabilistic modeling, and qualitatively gauge the perception of this abrupt transition. METHODS: A total of 17 pathologists and residents participated in this study; these participants reviewed 25 additional test cases from the archives and completed a final psychologic survey. For each case, participants performed several different diagnostic tasks, and their results were recorded and compared with the original diagnoses performed using the gold standard method (ie, conventional microscopy). We performed Bayesian data analysis with probabilistic modeling. RESULTS: The overall analysis, comprising 1345 different items, resulted in a 9% (117/1345) error rate in using digital slides. The task of differentiating a neoplastic process from a nonneoplastic one accounted for an error rate of 10.7% (42/392), whereas the distinction of a malignant process from a benign one accounted for an error rate of 4.2% (11/258). Apart from residents, senior pathologists generated most discrepancies (7.9%, 13/164). Our model showed that these differences among career levels persisted even after adjusting for other factors. CONCLUSIONS: Our findings are in line with previous findings, emphasizing that the duration of transition (ie, lengthy or abrupt) might not influence the diagnostic performance. Moreover, our findings highlight that senior pathologists may be limited by a digital gap, which may negatively affect their performance with digital pathology. These results can guide the process of digital transition in the field of pathology.

Ki-67 Index of 55% Distinguishes Two Groups of Bronchopulmonary Pure and Composite Large Cell Neuroendocrine Carcinomas with Distinct Prognosis.

BACKGROUND: Little information is available concerning prognostic factors for bronchopulmonary large cell neuroendocrine carcinomas (BP-LCNECs) and even less is known about combined LCNECs (Co-LCNECs). We investigated whether an integrated morphological, immunohistochemical, and molecular approach could be used for their prognostic evaluation. METHODS: Morphological (including combined features), proliferative (mitotic count/Ki-67 index), immunohistochemical (napsin A, p40, TTF-1, CD44, OTP, SSTR2A, SSTR5, mASH1, p53, RB1, and MDM2), and genomic (TP53, RB1, ATM, JAK2, KRAS, and STK11) findings were analyzed in BP-LCNECs from 5 Italian centers, and correlated with overall survival (OS). The Ki-67 index was expressed as the percentage of positive cells in hot spots as indicated in the WHO 2019 Digestive System Tumors and, for Co-LCNECs, the Ki-67 index was evaluated only in the LCNEC component. RESULTS: A total of 111 LCNECs were distinguished into 70 pure LCNECs, 35 Co-LCNECs (27 with adenocarcinoma [ADC] and 8 with squamous cell carcinoma [SqCC]), and 6 LCNECs with only napsin A immunoreactivity. The Ki-67 index cutoff at 55% evaluated in the neuroendocrine component was the most powerful predictor of OS (log-rank p = 0.0001) in all LCNECs; 34 cases had a Ki-67 index <55% (LCNEC-A) and 77 had a Ki-67 index ≥55% (LCNEC-B). Statistically significant differences in OS (log-rank p = 0.0001) were also observed between pure and Co-LCNECs. A significant difference in OS was found between pure LCNECs-A and Co-LCNECs-A (p < 0.05) but not between pure LCNECs-B and Co-LCNECs-B. Co-LCNEC-ADC and LCNEC napsin A+ cases had longer OS than pure LCNEC and Co-LCNEC-SqCC cases (log-rank p = 0.0001). On multivariable analysis, tumor location, pure versus combined features, and napsin A, but no single gene mutation, were significantly associated with OS after adjustment for Ki-67 index and study center (p < 0.05). CONCLUSIONS: The Ki-67 proliferation index and the morphological characterization of combined features in LCNECs seem to be important tools for predicting clinical outcome in BP-LCNECs.

Clinical Application of a Real-Time Telepathology System for Frozen Section Diagnosis in Comparison With Optical Microscope.

Background: The imbalance between the increasing demand of highly specialized service and the reduction of specialists able to release this service is a global challenge for Pathology. This situation applies also to the setting of intra-operatory diagnostic: here the broad presence of Surgical divisions contrasts with the contraction of Pathology departments, progressively concentrated in few hospitals. The use of e-pathology device, such as remote-control microscopes, offers a possible solution to this imbalance. Aim: To prove the non-inferiority of function of a remote-control, real-time microscope named Nano-Eye Device (NED) with the optical microscope (OM) for intra-operatory histological diagnosis. Methods: The study was designed into two phases: discovery and validation. During the discovery phase features influencing the process of adaptation to NED were investigated in detail, focusing on the turnaround time (TAT). Validation phase investigated the diagnostic concordance between NED and OM; as well as sensitivity, specificity, and accuracy of NED in intra-operatory histological diagnosis. Results: During the discovery phase 250 cases were examined. TAT of NED was longer than that of OM (112 ± 89.8 vs. 36 ± 37.9 s) and influenced by the difficulty of the specimen, age of pathologist and the type of the specimen. In the validation phase (185 cases) TAT of NED reduced significantly to 92 ± 86.3 s (p: 0.01). NED showed a concordance rate of 98% with OM; the sensitivity (95.65%), specificity (100%), and diagnostic accuracy (98.87%) of NED were equal to that of OM. NED failed to work in 6% during the discovery phase and 4% in the validation. Conclusions: Taken as a whole, the functionality of NED is comparable to OM. It can be the alternative choice for hospital lacking on-site pathology services and one of the tool of e-pathology.

Combined Low Densities of FoxP3+ and CD3+ Tumor-Infiltrating Lymphocytes Identify Stage II Colorectal Cancer at High Risk of Progression.

The densities of CD3+ and CD8+ tumor-infiltrating lymphocytes (TILs), combined with tumor-node-metastasis (TNM) staging, have prognostic value for patients with nonmetastatic colorectal cancer. We compared the prognostic value of CD3+ and FoxP3+ TILs at the invasive front, TNM classifiers, and microsatellite (MS) status in a trial set of patients with stage II and III colorectal cancer (n = 413), by recursive partitioning with a classification and regression tree (CART). Significant prognostic factors and interactions were reassessed by logistic regression and Cox proportional-hazards modeling in the trial and a validation set (n = 215) of patients with stage II colorectal cancer. In the trial set, CART indicated that TIL numbers were of value only in predicting recurrence risk for stage II cancers, where low densities of FoxP3+ TILs ranked first and low densities of CD3+ TILs further stratifying risk. Multivariate analysis showed that TILs interacted with tumor stage (FoxP3+, P = 0.06; CD3+, P = 0.02) and MS instability (MSI; FoxP3+; P = 0.02). In stage II MS-stable cancers, concomitant low densities of both FoxP3+ and CD3+ TILs identified patients with the highest progression risk in the trial [HR 7.24; 95% confidence interval (CI), 3.41-15.4; P < 0.001] and the validation (HR 15.16; 95% CI, 3.43-66.9; P < 0.001) sets. FoxP3+ and CD3+ TIL load in colorectal cancer was more informative than other prognostic factors before the cancer progressed to lymph nodes. This prognostic information about TILs, including FoxP3+ cells, suggests that randomized controlled trials might be refined to include interactions between TNM status, molecular classifiers, and postsurgical treatments.

Primary breast leiomyosarcoma and synchronous homolateral lung cancer: a case report.

Radiological and histological features of breast leiomyosarcoma can mimic a wide variety of other breast lesions, such as mesenchymal tumors, breast lymphomas, poorly differentiated carcinomas and metaplastic breast carcinomas. The authors present the case of a 62-year-old woman with a primary breast leiomyosarcoma with synchronous ipsilateral lung adenocarcinoma. The latter was an incidental finding during pre-surgical staging examinations. Clinicopathological, immunophenotypic and imaging features cancer are described. A brief review of the literature on imaging findings and management of breast leiomyosarcoma is presented. The authors discuss the differential diagnoses in breast imaging and of the extra-mammary incidental findings. Surgical resection remains the cornerstone of treatment, while radiation therapy and chemotherapy remain to be defined on a single-patient basis.

Hepatic rosai-dorfman disease with coincidental lymphoma: report of a case.

Rosai-Dorfman disease (RDD; sinus histiocytosis with massive lymphoadenopathy) is a rare, usually nodal self-limited disease. Sometimes nodal disease is coupled with extranodal localizations, in which case the disease can follow a protracted clinical course characterized by remissions and relapses and, exceptionally, a fatal outcome. Exclusive extranodal localizations are rare and their prognosis variable. This study reports a case of RDD apparently limited to the liver coexisting with a diffuse (stage IV) relapsing follicular lymphoma. The patient is alive and well 24 months after the diagnosis of the lymphoma. It is conceivable that the lymphoma has induced RDD via an immunological disorder, possibly involving interleukin expression. The favorable outcome supports the belief that the prognosis of RDD is largely dependent on the number of extranodal sites involved, rather than on the specific sites themselves.

Inflammatory substrate with eosinophils may be present in bare-metal stent thrombosis.

Coronary stent thrombosis is a rare but life-threatening event after percutaneous revascularization. We report an in-vivo documentation of the pathologic process in the setting of a very late thrombosis within a bare-metal stent, showing eosinophil infiltrates. Interestingly, our case indicates that eosinophil infiltrates might not be a peculiarity of late drug-eluting stent thrombosis.