Aims Secretory carcinoma of breast (SCB) typically harbours ETV6-NTRK3 gene fusion. Pan-Trk immunohistochemistry analysis (IHC) has been shown to be sensitive for SCB diagnosis. However, weak focal pan-Trk nuclear staining was previously found in 10% of non-secretory breast carcinomas. To further examine pan-Trk IHC specificity, we evaluated pan-Trk staining in various breast carcinoma subtypes. Methods The study cohort consisted of 346 invasive breast carcinomas (IBCs), including 8 SCBs and 48 triple-negative histological mimickers (36 metaplastic carcinomas, including 12 matrix-producing carcinomas; 5 adenoid cystic carcinomas; 5 apocrine carcinomas; 2 acinic cell carcinomas), 101 triple-negative IBCs of no special type, 101 estrogen receptor (ER)-positive/HER2-negative IBCs and 88 HER2-positive IBCs. Six salivary gland secretory carcinomas were also included. Pan-Trk IHC was performed on tumours using a rabbit monoclonal pan-Trk antibody. Any nuclear staining in the invasive carcino

Aims A new molecular subtype classification was proposed for small-cell lung carcinoma (SCLC). We aimed to further validate the classification in various SCLC patient samples using immunohistochemistry (IHC) to highlight its clinical significance. Methods We analysed the protein expression of four subtype (achaete-scute family BHLH transcription factor 1 (ASCL1), neuronal differentiation 1 (NEUROD1), POU class 2 homeobox 3 (POU2F3) and Yes1-associated transcriptional regulator (YAP1)) and two predictive markers (delta-like ligand 3 (DLL3) and MYC) using IHC in 216 specimens from 195 SCLC patients, including 21 pairs of resected biopsy tumours. Associations among molecular subtypes, clinicopathological features and prognostic implications were also explored. Results The ASCL1, NEUROD1, POU2F3, YAP1, DLL3 and MYC-positive expression rates were 70.3%, 56.9%, 14.9%, 19.0%, 75.4% and 22.6%, respectively. DLL3 expression had positive and negative associations with that of ASCL1 and POU2F3/YA

Background Diagnosing paediatric Crohn’s disease (CD) based on histology can present challenges. We evaluate the histological spectrum of treatment-naïve biopsies from children with CD and assess these findings’ diagnostic and predictive value. Methods Three cohorts were identified: (1) 137 patients with CD, (2) 116 patients with ulcerative colitis (UC) and (3) 50 patients without inflammatory bowel disease. Biopsies from the gastrointestinal (GI) tract were re-examined for signs of active and chronic inflammation, including lymphocyte-pattern oesophagitis, focal enhancing gastritis and indicators of chronicity. Additionally, granulomas and microgranulomas (defined as clusters of 4–9 epithelioid histiocytes) were evaluated. Results Lymphocyte-pattern oesophagitis was observed in 15% of patients (n=20). Moderate-to-severe diffuse gastritis was noted in 50.4% of patients (n=68), while focal enhancing gastritis was identified in 11.1% (n=15). In terminal ileal biopsies, 46.1% exhibited ac