A 61-year-old male was admitted to the hospital on December 6, 2017 due to "abdominal distension, vomiting with wasting for 15 days". The patient developed postprandial abdominal distension with vomiting 15 days before admission. Visited a local hospital, gastroscopy showed gastric retention and duodenal stenosis; Enhanced abdominopelvic CT examination showed thickened intestinal wall, narrow lumen and gastric retention in the descending duodenum. Consider duodenal mass occupation (nature to be investigated), gastric retention. After receiving treatment such as fasting water, gastrointestinal decompression, anti-infection and nutritional support, the patient lost about 7.5 kg in weight in 10 days, and was later transferred to our hospital. Past history: No history of chronic disease, no history of infectious disease, no history of allergy, appendectomy 20 years ago. Physical examination in hospital: thin body and clear consciousness; Body temperature 36.2 ℃, pulse 76 beats/min, breathing 17 beats/min, blood pressure 102/68 mmHg (1 mmHg =0.133 kPa); The skin and mucosa of the whole body were not yellowed, and the superficial lymph nodes were not palpable and obviously swollen. The bilateral pupils are equal in size and round, and they are sensitive to light reflection. No dry and wet rales and pleural friction were heard in both lungs, the heart rhythm was uniform, and no pathological murmur was heard in the auscultation area of each valve; Soft abdomen, no tenderness and rebound pain in the whole abdomen, subcostal and subsword of liver and spleen, Murphy sign (-); Physiological reflexes are present, but pathological reflexes are not elicited. Admission auxiliary examination: blood routine: white blood cell count 5.12×109/L, neutrophil percentage 66.6%, hemoglobin 141 g/L; Blood biochemistry: ALT 22 U/L, albumin 36 g/L, total bilirubin 15.8 μ mol/L, creatinine 98 μ mol/L. procalcitonin (PCT) (using Thermo Fisher B.R.A.H.M.S PCT antibody kit or VIDAS B.R.A.H.M.S PCT antibody kit of Mérieux, France)<0.5 μ g/L, Positive fecal occult blood. Coagulation function and tumor markers were normal. PET-CT examination showed abnormally increased metabolic mass in the descending duodenum with a SUVmax of 6.1, which was consistent with malignant lesion. Electronic gastroscopy: irregular mass after the duodenal bulb. Biopsy pathology revealed moderately differentiated adenocarcinoma.