Pancreatic Insufficiency: This condition, where the pancreas does not produce enough digestive enzymes, is a common cause of greasy stools (steatorrhea) due to the malabsorption of fats.

Celiac Disease: An autoimmune disorder that causes the immune system to react to gluten, leading to inflammation and damage in the small intestine, which can result in malabsorption of fats and other nutrients.
Crohn's Disease: A type of inflammatory bowel disease (IBD) that can affect any part of the gastrointestinal tract, leading to symptoms including diarrhea, abdominal pain, and malabsorption, which can cause greasy stools.
Small Intestine Bacterial Overgrowth (SIBO): A condition where there is an abnormal increase in the bacteria that inhabit the small intestine, which can lead to malabsorption and symptoms like bloating, gas, and greasy stools.

Cystic Fibrosis: A genetic disorder that can lead to severe damage to the lungs, digestive system, and other organs in the body. It affects the cells that produce mucus, sweat, and digestive juices, leading to malabsorption and greasy stools.
Whipple's Disease: A rare, systemic bacterial infection caused by Tropheryma whipplei, which can lead to malabsorption, weight loss, and other systemic symptoms, including greasy stools.

Abetalipoproteinemia: A rare inherited disorder that affects the absorption of fat and fat-soluble vitamins, leading to severe deficiencies and symptoms including greasy stools.
Short Bowel Syndrome: A condition where a significant portion of the small intestine is missing or not functioning, which can lead to malabsorption of nutrients, including fats, resulting in greasy stools.
Lipid Storage Diseases: A group of rare genetic disorders that affect the breakdown and storage of lipids, which can lead to the accumulation of lipids in the body and symptoms like greasy stools in some cases.