Differential Diagnosis

• Single most likely diagnosis
  • Chronic lymphocytic leukemia (C): This is the most likely diagnosis due to the patient's age, symptoms (increasing weakness, weight loss, generalized lymph node enlargement, and hepatosplenomegaly), laboratory findings (absolute lymphocytosis with the majority of cells being CD5+), and the presence of a mild antiglobulin-positive hemolytic anemia. Chronic lymphocytic leukemia (CLL) is a type of cancer that affects the blood and bone marrow, characterized by the production of an excessive number of immature white blood cells, known as lymphocytes. The CD5+ marker is commonly found in CLL.
• Other Likely diagnoses
  • Hairy cell leukemia (F): Although less likely than CLL, hairy cell leukemia could be considered due to the patient's symptoms such as hepatosplenomegaly and pancytopenia (not explicitly mentioned but possible given the clinical context). However, the CD5+ marker and the specific laboratory findings point more towards CLL.
  • Myelodysplastic syndrome (G): This could be a consideration given the patient's age and some of the symptoms like weakness and weight loss. However, the specific finding of CD5+ lymphocytosis and the clinical presentation lean more towards a lymphoproliferative disorder like CLL.
• Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
  • Acute lymphoblastic leukemia (A): Although less common in a 70-year-old and less likely given the CD5+ marker and the clinical presentation, ALL can present with similar symptoms and laboratory findings. It's crucial to distinguish between ALL and CLL due to significantly different treatment approaches and prognoses.
  • Acute promyelocytic leukemia (B): This is a medical emergency due to the risk of disseminated intravascular coagulation (DIC). While the presentation doesn't strongly suggest APL, any acute leukemia diagnosis is critical and requires immediate attention.
• Rare diagnoses
  • Fanconi's anemia (E): This is a rare genetic disorder that affects the body's ability to produce new blood cells, leading to bone marrow failure. It typically presents at a younger age and is characterized by congenital abnormalities, which are not mentioned in the scenario.
  • Myeloid metaplasia with myelofibrosis (H) and Polycythemia vera (I): These myeloproliferative neoplasms could present with hepatosplenomegaly but are less likely given the lymphocytosis and CD5+ marker. They are included here due to the hepatosplenomegaly but are not strong contenders based on the overall clinical picture.