Differential Diagnosis for a 76-year-old with Rheumatoid Arthritis (RA) and a Palpable Spleen

• Single most likely diagnosis:
  • Felty's Syndrome: This is a condition characterized by the combination of rheumatoid arthritis, splenomegaly (enlarged spleen), and anemia, often with neutropenia. The presence of a palpable spleen in a patient with RA makes Felty's Syndrome a strong consideration.
• Other Likely diagnoses:
  • Lymphoma: Patients with RA have an increased risk of developing lymphoma, which can cause splenomegaly. The chronic inflammation in RA may contribute to the development of lymphoma.
  • Chronic Lymphocytic Leukemia (CLL): CLL can cause splenomegaly and is more common in older adults. Although not directly related to RA, the coincidence of RA and CLL could explain the findings.
• Do Not Miss diagnoses:
  • Splenomegaly due to Infection: Certain infections (e.g., endocarditis, abscesses) can cause splenomegaly and are critical to diagnose promptly due to their potential severity and need for specific treatment.
  • Hematologic Malignancies other than Lymphoma: Conditions like myeloproliferative neoplasms (e.g., myelofibrosis) can cause splenomegaly and have significant implications for patient management and prognosis.
• Rare diagnoses:
  • Amyloidosis: Although rare, amyloidosis can cause splenomegaly and is associated with chronic inflammatory diseases like RA. It's a diagnosis that might not be immediately considered but could explain the splenomegaly in the context of RA.
  • Sarcoidosis: Sarcoidosis can involve multiple organs, including the spleen, leading to splenomegaly. It's less commonly associated with RA but could be a rare cause of splenomegaly in this context.