Pancreatic Adenocarcinoma: This is the most common malignancy of the pancreas, and the head of the pancreas is the most frequent location. It often presents with jaundice, weight loss, and abdominal pain.

Chronic Pancreatitis: Inflammation of the pancreas can cause a mass-like appearance in the head of the pancreas, often associated with a history of pancreatitis, abdominal pain, and sometimes diabetes.
Ampullary Carcinoma: A malignancy arising from the ampulla of Vater, which is located near the pancreatic head, can cause obstructive jaundice and a mass in the pancreatic head.
Neuroendocrine Tumors: These tumors can occur in the pancreatic head and may be functional (producing hormones) or non-functional, often presenting with symptoms related to hormone production or mass effect.

Lymphoma: Although less common, lymphoma involving the pancreas can mimic a pancreatic head mass and is crucial to diagnose due to its different treatment approach.
Metastasis: Metastatic disease to the pancreas from other primary sites (e.g., lung, breast, colon) can present as a mass in the pancreatic head and is important to identify for appropriate management.
Duodenal Carcinoma: A malignancy of the duodenum adjacent to the pancreatic head can be difficult to distinguish from a primary pancreatic tumor and requires accurate diagnosis for proper treatment.

Solid Pseudopapillary Neoplasm (SPN): A rare, low-grade malignant tumor that can occur in the pancreas, more commonly in young women, and often has a better prognosis than pancreatic adenocarcinoma.
Pancreatic Lymphangioma: A rare, benign tumor composed of lymphatic vessels that can present as a cystic mass in the pancreatic head.
Intraductal Papillary Mucinous Neoplasm (IPMN): A tumor that grows within the pancreatic ducts and can cause a mass-like appearance, particularly if it involves the main pancreatic duct in the head of the pancreas.