PD-L1 (22C3) expression and prognostic implications in esophageal squamous cell carcinoma.

Programmed cell death-ligand 1 (PD-L1) clone 22C3 is the only Food and Drug Administration-approved companion diagnostic test for pembrolizumab for the treatment of esophageal squamous cell carcinoma (ESCC). However, prior studies conducted in Asia and Europe have used various PD-L1 antibody clones other than 22C3. We aimed to study the expression profile of PD-L1, specifically of clone 22C3, in ESCC and its significance with regards to histological features, clinical parameters, and overall survival in a case series from two large US hospital systems.

Spectra of well-differentiated neuroendocrine lesions in the extrahepatic biliary system: a case series.

Aims: Neuroendocrine tumours (NETs) occurring in the extrahepatic biliary system are exceedingly rare. While NETs typically manifest as mass lesions, the occurrence of microscopic neuroendocrine cell proliferation without a distinct mass remains undocumented at this location. This study aims to characterise the clinicopathological features of a series of well-differentiated neuroendocrine lesions involving the extrahepatic biliary tree, including mass forming NETs and microscopic non-mass-forming neuroendocrine cell proliferation, designated neuroendocrine cell micronests (NCMs).

Follow-up biopsies in gastrointestinal immune checkpoint inhibitor toxicity may show markedly different inflammatory patterns than initial injury.

Colitis is a common manifestation of immune checkpoint inhibitor (ICI) toxicity and can present with varied histologic patterns of inflammation, some of which have been shown to be associated with specific ICI drug types. Although the histologic features of ICI colitis seen at the time of diagnosis have been described, there have been few reports following these patients over time. We evaluated initial and follow-up biopsies in 30 patients with ICI colitis and found that 37% of patients developed a different pattern of injury on follow-up biopsy compared to the initial biopsy.

INSM1 is a useful neuroendocrine marker to differentiate pancreatic serous cystadenoma from pancreatic well-differentiated neuroendocrine tumors in cytology and surgical specimens.

Introduction: Differentiating pancreatic serous cystadenoma (SCA) from well-differentiated neuroendocrine tumors (WDNETs) based on histomorphology is critical yet challenging, particularly in small biopsy samples. Our study aimed to examine the expression profile of INSM1 in cytologic and surgical resection specimens from pancreatic SCA to evaluate its potential as a discriminative marker against pancreatic WDNET.

Methods: We characterized INSM1 immunohistochemistry in 34 patients with pancreatic SCA, comprising 23 surgical resections and 11 cytology specimens.