Journal of Clinical Pathology最新文献

Background: Deep learning (DL) models are effective pre-screening tools for detecting mismatch repair deficiency (dMMR) in colorectal carcinoma (CRC). These models have been trained and validated on large cohorts from the Northern Hemisphere, without representation of African samples. We sought to determine the performance of a DL model in an ethnically heterogeneous cohort of patients from South Africa.

Methods: Our cohort comprised 197 CRC resection specimens, with scanned whole slide images tessellated and inputted into a transformer-based DL model trained on large international cohorts. Model performance was evaluated using area under the receiver operating characteristic curve (AUROC), sensitivity and specificity. The maximal Youden's J index was calculated to determine the optimal cut-off threshold for the model prediction score.

Results: Our model yielded an AUROC of 0.91 (±0.05). Using a prediction score threshold of 0.620 produced an overall sensitivity of 85.7% (95% CI 73.3% to 92.9%) and a specificity of 82.4% (95% CI 75.5% to 87.7%). The false negative cases were predominantly left-sided (71.4%) and did not show the typical dMMR/microsatellite instability-high histological phenotype. Sensitivity was lower (50%-75%) in cases showing isolated PMS2 or MSH6 loss of staining. Calibrating the classification threshold to 0.470, the sensitivity was optimised to 95.6% (95% CI 86.3% to 98.9%) with a specificity of 69.6% (95% CI 61.8% to 76.4%). This would have resulted in excluding 103 cases (52.3%) from downstream immunohistochemical (IHC) or molecular testing.

Conclusions: Following appropriate region-specific calibration, we have shown that this model could be employed to accurately prescreen for dMMR in CRC, thereby reducing the burden of downstream IHC and molecular testing in a resource-limited setting.

Aims: Fam-trastuzumab deruxtecan-nxki (T-DXd) was recently approved for advanced stage or metastatic solid tumours with human epidermal growth factor receptor 2 (HER2) immunohistochemical (IHC) 3+ staining. Data on HER2 IHC testing and knowledge of genomic correlates in lung cancer are scarce. This study analyses genomic characteristics of HER2-expressing tumours and addresses issues with preanalytical variables for lung cancer specimens.

Methods: HER2 IHC staining was performed on selected archival cytology and surgical pathology lung cancer specimens for patients eligible for T-DXd therapy. Patient and tumour characteristics and next-generation sequencing (NGS) data were correlated with HER2 IHC results.

Results: 166 patients with thoracic tumour samples had HER2 expression assessed: 46% were IHC 0, 28% IHC 1+, 13% IHC 2+ and 13% IHC 3+. HER2 IHC scores were overall lower for cytology cell blocks as compared with surgical pathology specimens; 79% of cases with paired specimens had a decrease in their HER2 IHC score from their surgical specimen to their paired cytology specimen. Of specimens with HER2 IHC 3+ and NGS available, only 14% (3/21) had concomitant ERBB2 alterations. Among all specimens, ERBB2 point mutations were noted in 4% (4/110) and ERBB2 amplification in 3% (3/110). The majority of HER2 3+ cases with paired NGS (17/21, 81%) had non-ERBB2 genomic alterations, including: KRAS, TP53, and STK11 mutations.

Conclusions: HER2 IHC 3+ is seen in a small but clinically significant proportion of samples and is associated with a variety of co-occurring non-ERBB2 genomic alterations. Preanalytical variables including specimen fixation can significantly impact the assessment of HER2 expression via immunohistochemistry.

Aims: This study aimed to re-evaluate the incidence of hydatidiform mole (HM) and determine gestational trophoblastic disease (GTD) registration rates in Ireland following the establishment of the National GTD Registry in 2017.

Methods: We performed a 3-year retrospective audit of HM cases (January 2017 to December 2019) reported in our centre. In 2019, we surveyed Irish pathology laboratories to determine the number of HMs diagnosed nationally and compared this data to that recorded in the National GTD Registry. Additionally, we compared both local and national HM incidence rates to those reported internationally.

Results: In the 3-year local audit, we identified 87 HMs among 1856 products of conception (POCs) providing a local HM incidence rate of 3.92 per 1000 births. The 1-year pathology survey recorded 170 HMs in 6008 POCs, yielding a national incidence rate of 2.86 per 1000 births. Importantly, the local HM incidence rate exceeded the national incidence rate by 37% and the local partial HM incidence (1 in 296 births) was 64% higher than the nationally incidence rate (1 in 484 births). Notably, 42% of the HM and atypical POCs diagnosed nationally were not reported to the National GTD Registry.

Conclusions: Our study reveals increased HM incidence rates both locally and nationally compared with previous Irish studies. The higher local PHM incidence may reflect more limited access to ploidy analysis in other pathology laboratories nationally. Significantly, almost half of the women with diagnosed or suspected HM were not registered with the National GTD Centre.

Aims: Colorectal carcinoma (CRC) is a common cause of morbidity and mortality worldwide, and an emerging public health problem in sub-Saharan Africa. Several authors have described an increased frequency of mismatch repair-deficient (dMMR) CRC in sub-Saharan Africa, but these tumours remain poorly characterised molecularly. We sought to interrogate the somatic molecular genetic landscape of dMMR CRC in a cohort of young patients to better inform Lynch syndrome (LS) screening strategies and personalised medicine approaches in our setting.

Methods: 32 patients (aged <60 years) were identified with dMMR CRC. DNA was extracted from selected formalin-fixed paraffin-embedded (FFPE) tissue resection samples and subjected to amplicon-based next-generation sequencing (NGS).

Results: Pathogenic or likely pathogenic variants were detected in the corresponding MMR gene in 14 of 18 (78%) MLH1/PMS2-deficient tumours, 5 of 8 (63%) MSH2/MSH6-deficient tumours, 1 of 4 (25%) tumours with isolated MSH6 loss and 0 of 2 tumours with isolated PMS2 loss. Previously unreported variants were identified in MLH1 (three) and MSH2 (one). Cases with a variant allele frequency suggesting a germline mutation were identified in MLH1 (eight), MSH2 (two) and MSH6 (one). Only one MMR gene variant was detected in more than one patient (MLH1 p.Q510*). Four POLE/POLD1 exonuclease domain variants were identified, one of which was previously unreported.

Conclusion: The spectrum of disease-causing MMR gene variants in our population necessitates NGS testing for LS screening. This study also highlights the role of somatic testing on readily available FFPE samples to generate data on the epidemiology of CRC in different settings.

Aims: To clarify claudin18.2 expression and its clinicopathological features in various cancers, especially in lung adenocarcinoma.

Methods: Immunohistochemistry staining and fluorescence in situ hybridisation (FISH) were performed to detect claudin18.2 expression and CLDN18 gene rearrangement in adenocarcinoma from different organs.

Results: The results showed that claudin18.2 expression was found in 68% (27 of 40) of lung mucinous adenocarcinoma, 52% (16 of 31) of cholangiocarcinoma, 2% (10 of 423) of colorectal adenocarcinoma tissue microarray, 27% (6 of 22) of colorectal mucinous adenocarcinoma and 30% (3 of 10) of cervical adenocarcinoma, but not in all 39 cases of invasive breast adenocarcinoma by immunohistochemistry staining. There was significantly positive correlation between ratio of claudin18.2-positive carcinoma cells and staining intensity in lung mucinous adenocarcinoma and cholangiocarcinoma. Claudin18.2 expression was much more in female patients than male patients with lung mucinous adenocarcinoma. In addition, cholangiocarcinoma with claudin18.2 expression was more aggressive and had perineural invasion. Intraductal papillary neoplasm of the bile duct and epithelial dysplasia of the adjacent bile in cholangiocarcinoma also showed claudin18.2 expression. All three cases of cervical adenocarcinoma with claudin18.2 expression were moderately differentiated adenocarcinoma including one human papillomavirus (HPV)-associated carcinoma, two non-HPV-associated and gastric-type carcinoma. CLDN18 gene rearrangement was not found in all 22 cases with high claudin18.2 expression by FISH.

Conclusions: Our results suggest claudin18.2 might be a potential biomarker for targeted therapy on lung mucinous adenocarcinoma, cholangiocarcinoma, colorectal mucinous adenocarcinoma and gastric-type cervical adenocarcinoma.

Aims: To meet the flexible learning needs of pathology residents preparing for national board examinations, a joint distance learning approach was developed using both asynchronous and synchronous activities with whole slide images, drawing on empirical educational research on online distance learning.

Methods: In a case study of an implementation of the designed joint distance learning approach with a geographically dispersed group of pathology residents in Finland, the participants' perceptions were measured with a 12-item questionnaire covering the value of the learning opportunity, the quality of the sociocognitive processes and their emotional engagement and social cohesion. Communication during the online session was also recorded and analysed to provide objectivity to the self-report data.

Results: The effectiveness of joint online learning for knowledge acquisition and preparation for national board examinations was highly rated. However, despite strong emotional engagement during synchronous activities, participants reported minimal interpersonal interaction, which was also reflected in the recordings of the online session.

Conclusion: Using a technology integration framework and guided by the principles of self-determination theory, joint distance learning is emerging as a beneficial addition to postgraduate pathology programmes in preparation for national examinations. However, to realise the full potential of interpersonal interaction, participants should be prepared for an appropriate mindset.