Differential Diagnosis for Poor Appetite, Weight Loss, Abdominal Pain, and Enlarged Spleen

Single Most Likely Diagnosis

• Lymphoma: Given the significant weight loss, poor appetite, and notably enlarged spleen (18cm), lymphoma is a strong consideration. The symptoms of lymphoma can include systemic symptoms like weight loss and loss of appetite, along with localized symptoms such as abdominal pain due to organ involvement, including the spleen.

Other Likely Diagnoses

• Chronic Lymphocytic Leukemia (CLL): CLL can cause splenomegaly and systemic symptoms like weight loss and decreased appetite. The disease often presents in older adults and can lead to significant enlargement of the spleen.
• Liver Cirrhosis: While primarily known for liver dysfunction, cirrhosis can lead to splenomegaly due to portal hypertension. Weight loss and poor appetite can also be present, especially in advanced stages.
• Gastric Cancer: Gastric cancer can cause epigastric pain, weight loss, and poor appetite. Although less commonly associated with significant splenomegaly, metastasis to the spleen or splenic involvement due to tumor spread can occur.

Do Not Miss Diagnoses

• Splenic Abscess or Infarct: Although less likely, a splenic abscess or infarct can present with acute abdominal pain and splenomegaly. These conditions are medical emergencies requiring prompt intervention.
• Pancreatic Cancer: Pancreatic cancer can cause weight loss, poor appetite, and abdominal pain. While not all cases present with significant splenomegaly, the condition's severity and potential for rapid progression make it a critical diagnosis not to miss.
• Tuberculosis: TB can affect multiple systems, including the gastrointestinal system and spleen, leading to weight loss, abdominal pain, and splenomegaly. It's particularly important to consider in endemic areas or in individuals with risk factors.

Rare Diagnoses

• Sarcoidosis: Sarcoidosis is a systemic disease that can involve any organ, including the spleen, and cause splenomegaly. It might also lead to weight loss and abdominal pain, although these are less common presentations.
• Primary Splenic Neoplasms: Tumors originating in the spleen, such as lymphangiomas or hemangiomas, are rare and can cause splenomegaly. However, they are less likely to cause systemic symptoms like significant weight loss and poor appetite.
• Amyloidosis: Amyloidosis can involve the spleen, leading to splenomegaly, and may also cause weight loss and gastrointestinal symptoms. It is a rare condition with a wide range of presentations.