Morphological and p40 immunohistochemical analysis of squamous differentiation in endoscopic ultrasound guided fine needle biopsies of pancreatic ductal adenocarcinoma

Beate Haugk,Philip Sloan,John Leeds,Paul Bassett,Antony Darne,Claire Jones,Manu Nayar,Kofi Oppong,David Horton,Thomas Ness

doi:10.1038/s41598-021-00652-5

Abstract

The basal-like molecular subtype of pancreatic ductal adenocarcinoma (PDAC) is associated with poor prognosis and upregulation in TP63ΔN (p40) network. Adenosquamous histology can be observed. This study assessed immunohistochemical p40 expression in fine needle biopsy (FNB) samples with PDAC and association with cytomorphological features of squamous differentiation and clinical data. 106 EUS FNBs with PDAC were assessed for eight cytomorphological features of squamous differentiation. P40 H-score (intensity 0–3 × percentage positive nuclei) was analysed for association with morphological features, patient age, gender, operability, chemotherapy and survival. P40 H-score in 14 paired FNBs and resections was compared. P40 h-score was 1–3 in 31%, 4–30 in 16% and > 30 in 13% of FNBs. It was significantly associated with intercellular bridges, elongated cell shape, sharp cell borders, angular nuclei with homogenous chromatin (p < 0.001) and dense cytoplasm (p = 0.002). Keratinisation was not seen. Inoperable patients (n = 81) had a shorter median survival for h-score > 30 (n = 9, 1.8 months) than for h-score ≤ 30 (n = 66, 6.7 months) not quite reaching statistical significance (p = 0.08). P40 was significantly associated with squamous morphology in FNBs with PDAC. P40 H-score > 30 showed a trend towards shorter survival in inoperable patients. Squamous differentiation may be a treatment target in PDAC.

Highlights

The basal-like molecular subtype of pancreatic ductal adenocarcinoma (PDAC) is associated with poor prognosis and upregulation in TP63ΔN (p40) network
The following 10 cases were excluded: definite or possible diagnosis of metastatic adenocarcinoma, ampullary or common bile duct adenocarcinomas on subsequent resection histology, adenocarcinomas apparently arising in the context of intraductal papillary mucinous neoplasms (IPMNs) and adenocarcinomas with non-pancreatobiliary histological type. 16 matching resection specimens from fine needle biopsy (FNB) samples containing PDAC were identified
In a cohort of over 100 consecutive PDAC FNB samples, we found p40 to be a reliable immunohistochemical marker of squamous d ifferentiation[18] to be expressed in over half of the samples, with 13% showing expression in at least 10% of tumour cells

Summary

Introduction

The basal-like molecular subtype of pancreatic ductal adenocarcinoma (PDAC) is associated with poor prognosis and upregulation in TP63ΔN (p40) network. Over the past decade extensive work based mainly on resected PDAC tissues was performed to identify molecular subtypes of PDAC to facilitate precision medicine in order to improve outcome[6,7,8,9] This has highlighted a complex molecular landscape in PDAC involving multiple genetic, epigenetic and tumour microenvironmental factors[5,9] with significant heterogeneity between and within tumours and limited clinical value. Two main epithelial subtypes of PDAC appear to be emerging: (1) the basal-like/quasi-mesenchymal/squamous type which is mainly referred to as basal-like; this is more commonly associated with p53 mutation, upregulation in TP63ΔN (p40) network, and clinically poor prognosis. Technical developments over the last decade have resulted in new generation biopsy needles which provide fine needle biopsies (FNBs) with intact tissue fragments showing higher accuracy in the diagnosis of PDAC and providing paraffin embedded intact tissue for ancillary tests[15]

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