An untapped resource: characteristics of thrombus recovered from intermediate or high risk pulmonary embolus patients.

INTRODUCTION: Response to anticoagulation varies during management of acute hospitalized pulmonary embolism. We aimed to study thrombus histology in pulmonary embolism samples removed during acute surgical embolectomy to evaluate whether thrombus morphology was similar between patients and whether there was an association with duration of symptoms and/or resolution on follow up imaging. METHODS: This was a retrospective observational single center study at the University of Rochester Medical Center. We evaluated patients that underwent acute surgical embolectomy and followed up in our clinic 2 - 4 months after the event with Ventilation/Perfusion (V/Q) scan obtained for all regardless of symptoms. Thromboemboli were formalin fixed and processed for light microscopy in the hospital histopathology laboratory. Four-micron thick sections were stained with hematoxylin and eosin, Masson trichrome, and Verhoeff elastic tissue stains. Immunohistochemistry was performed using anti-CD31 and anti-CD68. Slides were independently evaluated for time-dependent microscopic changes using Irniger's classification by two blinded pathologists. RESULTS: Sixteen patients underwent embolectomy with fifteen having V/Q imaging at follow up. The majority of patients were female. Samples showed a generally similar overall architecture that included a central core composed primarily of red blood cells and fibrin and an outer layer of platelets and monocytes. Two samples had evidence of fibrosis and recanalization. CONCLUSIONS: We found heterogeneous histopathology in samples obtained during acute embolectomy. Further prospective studies should systematically characterize clot morphology and evaluate treatment response and outcomes. Careful thrombus specimen measurement and consistent sampling for sections will be required to draw firm conclusions.

ROC analysis of p16 expression in cell blocks of metastatic head and neck squamous cell carcinoma.

BACKGROUND: Oropharyngeal squamous cell carcinoma is associated with human papillomavirus (HPV) and often presents with early metastasis to cervical neck lymph nodes that are amenable to fine-needle aspiration (FNA). The most common method of HPV status determination is p16 immunohistochemistry (IHC). The literature suggests that a lower threshold is needed for p16 positivity on cell block. We examined and quantified p16 IHC staining on cell block and used receiver operating characteristics (ROC) curve analysis to determine an optimal cutoff value with high sensitivity and specificity. METHODS: Thirty-six FNAs of metastatic squamous cell carcinoma from cervical lymph nodes with p16 IHC were evaluated. The p16 stain was quantified in 5% increments and high-risk HPV mRNA in situ hybridization was performed as a gold standard test. Statistical analysis was performed. RESULTS: Interobserver variability was evaluated and was shown to be low with an intraclass correlation coefficient of 0.857. ROC analysis was performed and showed that a cell block p16 IHC cutoff of 15% yielded the highest sensitivity (80%) and specificity (81.8%). CONCLUSION: Our data show that a threshold of 15% p16 staining in cell block maximizes sensitivity and specificity.

The utility of high-risk human papillomavirus E6/E7 mRNA in situ hybridization in assessing HPV status on cell block.

INTRODUCTION: Assessment of human papillomavirus (HPV) status is critical to the treatment and prognosis of patients with oropharyngeal squamous cell carcinoma. Patients often present with enlarged cervical lymph nodes which are amenable to fine needle aspiration (FNA) and cell block creation. The most widely used method for assessing HPV status is the surrogate marker p16. Other HPV specific methods such as high-risk HPV E6/E7 mRNA in situ hybridization (ISH) have been shown to perform as well as p16 and are easier to interpret. Our study evaluates the utility of high-risk HPV mRNA ISH in cell block specimens. METHODS: Thirty-six cases of metastatic squamous cell carcinoma in cervical neck lymph node FNAs were identified over a 3-year period. All cases had p16 immunohistochemistry (IHC) performed on cell block. HR HPV mRNA ISH was performed on the cell block and compared to the p16 results. Additionally, p16 and HR HPV mRNA ISH status was assessed in those cases with corresponding surgical resections. RESULTS: HR HPV mRNA ISH confirmed the p16 IHC (either positive or negative) in 24 of the 36 cases (66.7%). Six false negative cases were p16 negative/HR HPV mRNA ISH positive. HR HPV mRNA ISH was positive in 75% of the four p16 equivocal cases. Two cases were p16 positive/HR HPV mRNA ISH negative. CONCLUSIONS: HR HPV mRNA ISH is no more difficult to perform in the IHC lab and is easier to interpret than p16 IHC. HR HPV mRNA ISH is a useful alternative to p16 in cell block specimens.

Cell blocks in urine cytopathology: do they add value to the diagnosis? A pilot study.

INTRODUCTION: The utility of cell block (CB) preparation is well established in cytopathology. Despite 23.3% of College of American Pathologists-accredited laboratories using CB with liquid-based preparations on urine cytology (UC) cases, there are very few studies on their performance. To determine their usefulness, we conducted a retrospective review of UC cases that received CB. MATERIALS AND METHODS: We identified 27 UC cases with ThinPrep (TP) and CB preparation between 2016 and 2020 at our institution. Clinical history and follow-up data were compiled. A blinded review of TP alone, and TP together with CB, was performed by 2 pathologists and 2 cytotechnologists. Diagnoses were rendered in accordance with The Paris System for Reporting Urine Cytology. RESULTS: Blood and acute inflammation were common background elements in cases that received CB preparation. In total, CB upgraded the diagnosis in 7 of 27 cases (26%). The maximum utility of CB preparation was seen in indeterminate cases where 60% (6 of 10) were upgraded, including 71% (5 of 7) of atypical urothelial cells (AUC) and 30% (1 of 3) of suspicious for high-grade urothelial carcinoma (HGUC). One case (1 of 12, 8%) diagnosed as negative for HGUC on TP was diagnosed as low-grade urothelial neoplasia on CB. CONCLUSIONS: Our results demonstrate that adjunct use of CB preparation aids in a definitive diagnosis on AUC category and may be helpful in cases with cell clusters or tissue fragments, or cases suspicious for HGUC. Further correlation studies are warranted in this area to expand our knowledge about the utility of CBs in urine cytology.