The ‘LVSI checklist’ lists features that favour LVSI and pseudo-LVSI. Lymphovascular space invasion (LVSI) assessment in endometrial cancer can be challenging at times. This review provides practical guidance and is summarised in this LVSI checklist. A list of morphological clues to true and pseudo-LVSI is provided for practising pathologists to support the assessment of LVSI.

Molecular, immunohistochemical, and clinical understanding of salivary gland lesions has advanced in recent years, yielding reclassification and a shift in nomenclature of benign and malignant neoplasms. Pathogenic understanding, clinical treatment, and patient prognostication will improve with increasing knowledge of these diverse entities.

Manual assessment of Ki67 hotspots is difficult and prone to variability. Automated Ki67 hotspot assessment correlated strongly with manual Ki67 assessment and provided higher Ki67 PIs. DL-based automated Ki67 assessment has high clinical applicability, because it does not depend on virtual alignment of slides and correlates strongly with manual scoring.

To distinguish malignant from benign lesions, especially in situ SUM versus atypical lentiginous melanocytic proliferations, aCGH analysis should be performed when the MC is above 45/mm. This pangenomic method can detect oncogene amplifications, as well as a number of CNV >3, which strongly support the diagnosis of malignancy.

Breslow thickness (BT) is the most important histological prognostic feature for melanoma prognosis. A count of invasive melanoma cell nuclei may refine and improve BT. This study demonstrates proof of concept that this proposal is correct.

Nonampullary small bowel medullary carcinomas are associated with coeliac disease and show higher rates of mismatch repair deficiency and PD-L1 positivity, as well as a more favourable outcome, compared to nonmedullary cases. They should be considered a distinct subtype of small bowel adenocarcinoma.

Despite loss of differentiation and phenotypical plasticity, methylation signatures are retained in undifferentiated, de-differentiated and trans-differentiated melanomas. DNA methylation profiling enhances diagnostic precision, proving useful in these diagnostically challenging cases.

Usual interstitial pneumonia (UIP) in a transbronchial cryobiopsy from a patient with an underlying connective tissue disease (CTD). UIP is one of the patterns seen in cryobiopsies from CTD patients and usually is not separable from UIP in patients with idiopathic pulmonary fibrosis or fibrotic hypersensitivity pneumonitis in this type of biopsy.

Mesonephric-like adenocarcinomas (MLA) show negative SOX17 (B), diffuse positive PAX8 (C), focal strong TTF1 (D), negative GATA3 (E) and focal positive CD10 (F).

HER2-positive grade 1 carcinomas are uncommon and more often have marked nuclear pleomorphism and lack oestrogen receptor and progesterone receptor expression compared with HER2-negative grade 1 carcinomas. A HER2-positive result in the core biopsy was confirmed in 11 of 13 tumours that had repeat testing.

This study describes the spectrum of extrahepatic biliary well-differentiated neuroendocrine lesions, ranging from incidental microscopic neuroendocrine cell micronests (NCMs) to grossly apparent mass-forming neuroendocrine tumours (NETs), potentially requiring different clinical management.

BAP1-inactivated tumours (BIMT) are indolent proliferations of dermal epithelioid melanocytes with nuclear loss of BAP1, and can present with severe cytological atypia. PRAME (preferentially expressed antigen in melanoma) immunohistochemistry consistently shows patchy and weak staining in BIMT and serves as a reassuring tool to distinguish BIMT from melanoma.