Neutrophil Infiltration and Acinar-ductal Metaplasia Are the Main Pathological Findings in Pembrolizumab-induced Pancreatitis
Morihisa Hirota, Keigo Murakami, Akinobu Koiwai, Keita Kawamura, Yuki Yoshino, Atsuko Takasu, Ryo Kin, Tomofumi Katayama, Katsuya Endo, Takayuki Kogure, Takayoshi Meguro, Toshiharu Tabata, Kazuhiro Murakami, Kennichi Satoh
Abstract
The histopathological findings of immune checkpoint inhibitor (ICI)-induced pancreatitis have rarely been reported. A 56-year-old man with squamous cell carcinoma of the lung with bone metastasis was being treated with pembrolizumab, an anti-programmed cell death protein-1 antibody. After 13 doses, he was referred to our department due to pancreatitis. Despite characteristic symptoms of acute pancreatitis, imaging findings were similar to those of autoimmune pancreatitis. However, a histological examination showed neutrophil-based inflammatory cell infiltration and acinar-ductal metaplasia. Immunostaining showed CD8-positive T lymphocyte infiltration. This case revealed the characteristic histopathology of pembrolizumab-induced pancreatitis, which was previously poorly understood.