Differential Diagnosis for Chronic Abdominal Pain
The patient presents with chronic abdominal pain upon deep palpation, a recent normal colonoscopy, no bloody diarrhea, positive lactose intolerance, and a past medical history of non-insulin-dependent diabetes mellitus (NIDDM). Considering these factors, the differential diagnoses can be categorized as follows:
Single Most Likely Diagnosis
- Irritable Bowel Syndrome (IBS): Given the patient's positive lactose intolerance and the absence of alarming symptoms like bloody diarrhea, IBS is a plausible diagnosis. The chronic abdominal pain and the normal colonoscopy results also support this diagnosis, as IBS is a functional disorder without clear structural abnormalities.
Other Likely Diagnoses
- Lactose Intolerance Complications: Although the patient is already diagnosed with lactose intolerance, consuming lactose-containing products could exacerbate abdominal pain, suggesting that better management of lactose intolerance might be necessary.
- Non-alcoholic Fatty Liver Disease (NAFLD): Associated with NIDDM, NAFLD could cause chronic abdominal pain, especially if there is liver inflammation or fibrosis.
- Chronic Pancreatitis: Although less common, chronic pancreatitis can cause chronic abdominal pain and is associated with diabetes, which could be a consideration in this patient.
Do Not Miss Diagnoses
- Pancreatic Cancer: Although rare and less likely given the absence of significant weight loss or jaundice, pancreatic cancer is a deadly diagnosis that must be considered, especially in a patient with NIDDM, which is a risk factor.
- Inflammatory Bowel Disease (IBD): Despite the normal colonoscopy, it's essential to consider IBD, as it can have a patchy distribution and might not always be detected on a single colonoscopy. The absence of bloody diarrhea does not rule out IBD entirely.
- Intestinal Ischemia: This condition can cause chronic abdominal pain and is more common in patients with diabetes due to vascular disease.
Rare Diagnoses
- Celiac Disease: An autoimmune reaction to gluten, which can cause chronic abdominal pain and is associated with lactose intolerance due to the small intestine's inability to absorb lactose properly.
- Abdominal Migraine: A condition that can cause recurrent episodes of abdominal pain, often associated with other migraine symptoms.
- Eosinophilic Gastroenteritis: A rare condition characterized by eosinophilic infiltration of the gastrointestinal tract, leading to chronic abdominal pain among other symptoms.