What is the diagnosis and management plan for an 85-year-old lady with a history of Chronic Obstructive Pulmonary Disease (COPD) and Rheumatoid Arthritis (RA) on Methotrexate, presenting with recurrent left upper quadrant pain and nausea, with elevated Alanine Transaminase (ALT), Alkaline Phosphatase (ALP), and C-Reactive Protein (CRP), and intolerance to Proton Pump Inhibitors (PPIs)?

Differential Diagnosis for 85-year-old Lady with Left Upper Quadrant Pain and Nausea

Single Most Likely Diagnosis

• Gastroesophageal Reflux Disease (GERD) or Peptic Ulcer Disease: Given the patient's history of COPD and rheumatoid arthritis, and the use of methotrexate, which can increase the risk of gastrointestinal issues, along with the mild elevation of ALT and raised ALP, this diagnosis seems plausible. The patient's symptoms of left upper quadrant pain and nausea, although not typical, could be related to GERD or peptic ulcer disease, especially considering the lack of response to famotidine and intolerance to PPIs.

Other Likely Diagnoses

• Gastritis: The patient's symptoms and laboratory findings, such as elevated CRP and mild elevation of liver enzymes, could also suggest gastritis, possibly exacerbated by methotrexate or other factors.
• Pancreatitis: Although the patient does not have typical symptoms of pancreatitis, such as severe abdominal pain radiating to the back, the raised ALP and mild elevation of ALT could indicate pancreatic involvement.
• Cholecystitis or Biliary Colic: The patient's left upper quadrant pain and nausea could be related to gallbladder disease, especially considering the raised ALP, which can indicate biliary obstruction.

Do Not Miss Diagnoses

• Malignancy (e.g., Gastric or Pancreatic Cancer): Although less likely, it is crucial to consider malignancy in an elderly patient with persistent symptoms and elevated inflammatory markers (CRP 200). A delay in diagnosis could have severe consequences.
• Pulmonary Embolism: Although the patient's symptoms do not typically suggest pulmonary embolism, it is essential to consider this diagnosis in an elderly patient with COPD, as it can present atypically and has a high mortality rate if missed.
• Infectious Causes (e.g., Pyelonephritis or Pneumonia): The patient's elevated CRP and mild elevation of liver enzymes could indicate an infectious process, which would require prompt treatment to prevent severe consequences.

Rare Diagnoses

• Sphincter of Oddi Dysfunction: This rare condition could cause the patient's symptoms, especially if there is biliary colic or pancreatitis involved.
• Amyloidosis: Given the patient's long-standing rheumatoid arthritis, amyloidosis could be a rare consideration, although it would require further investigation to confirm.
• Eosinophilic Gastroenteritis: This rare condition could cause the patient's gastrointestinal symptoms, although it would be unusual in an elderly patient without a history of atopy or eosinophilia.