A Case of Anti‐ <scp>AMY1</scp> ‐Positive Lung Squamous Cell Carcinoma With Severe Hyperamylasemia Linked to Disease Progression

A 74-year-old man presented with abdominal pain. Preoperative evaluation for small bowel perforation revealed a 74-mm tumour shadow obstructing the right lower lobe bronchus. Endobronchial biopsy from the truncus intermedius was diagnostic of squamous cell carcinoma (SCC). Pathological findings in the small intestine were consistent with SCC. Based on other radiological findings, the patient was diagnosed with stage IVB (cT4N3M1c) lung SCC (LUSC). Serum amylase levels were elevated at 1693 U/L (pancreatic amylase 184 U/L) prior to treatment. AMY1 (2D4) immunohistochemistry was positive, confirming amylase-producing LUSC, a rarely reported entity. Amylase levels decreased to 203 U/L following combination therapy with carboplatin, nab-paclitaxel and pembrolizumab. The patient had no symptoms or signs of pancreatic or salivary gland disease. To our knowledge, this is the first reported case of LUSC with both histological evidence of amylase production and hyperamylasemia. This case provides new evidence that LUSC can produce amylase and cause hyperamylasemia.