Cholestasis due to intrahepatic or extrahepatic bile duct obstruction: The significantly elevated GGT (343) and Alkaline Phosphatase (210) levels, with relatively mild elevations in AST (50) and ALT (41), suggest a cholestatic pattern of liver injury. This pattern is often seen in conditions affecting the bile ducts, such as gallstones, tumors, or strictures.

Primary Biliary Cholangitis (PBC): This autoimmune disease primarily affects the bile ducts within the liver, leading to cholestasis. The elevated alkaline phosphatase and GGT levels are consistent with PBC, although further testing (e.g., anti-mitochondrial antibodies) would be needed for diagnosis.
Drug-induced Cholestasis: Certain medications can cause cholestasis, presenting with elevated alkaline phosphatase and GGT. A thorough medication history is essential to consider this diagnosis.
Viral Hepatitis: Although the pattern is more cholestatic than hepatocellular, viral hepatitis (especially hepatitis B and C) can present with a wide range of liver enzyme abnormalities. Serologic testing for hepatitis viruses would help in diagnosing this condition.

Pancreatic Cancer: This diagnosis is critical to consider due to its poor prognosis if not caught early. Obstruction of the bile duct by a pancreatic tumor can lead to the observed pattern of liver enzyme elevation. Imaging studies (e.g., CT or MRI) of the abdomen would be crucial in evaluating for this condition.
Cholangiocarcinoma: A malignancy of the bile duct, which can also cause obstructive jaundice and cholestasis. Its presentation can be similar to that of pancreatic cancer, with significant elevations in alkaline phosphatase and GGT.

Sclerosing Cholangitis: A chronic liver disease characterized by inflammation and scarring of the bile ducts inside and outside the liver. It can present with cholestatic liver enzyme elevations but is less common than other causes of cholestasis.
Histiocytosis X (Langerhans Cell Histiocytosis): A rare disorder in which the body accumulates too many immature Langerhans cells, part of the immune system. It can affect various organs, including the liver, and cause cholestasis among other symptoms.
Amyloidosis: A condition characterized by the deposition of amyloid (a particular type of protein) in various tissues, including the liver. It can cause a range of liver function abnormalities, including cholestasis, although this is a rare presentation.