Carcinoma of the pylorus is by far the most important differential diagnosis of adult pyloric stenosis.
Rare causes of pyloric obstruction include:
- adult pyloric hypertrophy
- scarring secondary to a benign gastric ulcer near the pylorus
- a chronic stricture resulting from a duodenal ulcer
- invasion of the pylorus by malignant lymph nodes e.g. non-Hodgkins lymphoma
- infiltration from a pancreatic carcinoma
Clues to the aetiology are provided by the history and examination.
- length of history: a history of several years of characteristic peptic ulcer pain in contrast to cancer with a painless history lasting months
- gross dilatation of the stomach favours a benign lesion
- the presence of a mass at the pylorus indicates probable malignant disease. However in rare instances a palpable inflammatory mass in association with a large duodenal ulcer can be detected.