Differential Diagnosis for Pancytopenia without Splenomegaly with Normal LDH

Single Most Likely Diagnosis

• Aplastic Anemia: This condition is characterized by the failure of the bone marrow to produce blood cells, leading to pancytopenia. The absence of splenomegaly and normal LDH levels supports this diagnosis, as aplastic anemia typically does not involve spleen enlargement and does not significantly elevate LDH.

Other Likely Diagnoses

• Myelodysplastic Syndromes (MDS): These are a group of disorders caused by poorly formed or dysfunctional blood cells, often leading to pancytopenia. While splenomegaly can occur, it's not a universal finding, and LDH can be normal in many cases.
• Paroxysmal Nocturnal Hemoglobinuria (PNH): A rare, acquired, life-threatening disease of the blood characterized by the destruction of red blood cells, bone marrow failure, and the potential for thrombotic events. PNH can present with pancytopenia without splenomegaly and normal LDH levels.
• Bone Marrow Infiltration (e.g., by cancer or fibrosis): Infiltration of the bone marrow by malignant cells or fibrotic tissue can lead to pancytopenia. The absence of splenomegaly and normal LDH could be seen in early stages or in specific types of infiltration.

Do Not Miss Diagnoses

• Leukemia (especially Acute Lymphoblastic Leukemia or Acute Myeloid Leukemia): Although leukemia often presents with splenomegaly and elevated LDH, early stages or certain subtypes might not. Missing a diagnosis of leukemia could be fatal due to the aggressive nature of the disease.
• Lymphoma: Similar to leukemia, lymphoma can infiltrate the bone marrow, leading to pancytopenia. While splenomegaly and elevated LDH are common, they are not universal, making lymphoma a "do not miss" diagnosis.
• Disseminated Tuberculosis: TB can affect the bone marrow, leading to pancytopenia. It's crucial not to miss this diagnosis due to its treatability with appropriate antibiotics.

Rare Diagnoses

• Glycogen Storage Disease Type Ib: A rare genetic disorder that affects the body's ability to regulate blood sugar levels and can lead to pancytopenia due to neutropenia and sometimes anemia and thrombocytopenia.
• Shwachman-Diamond Syndrome: A rare congenital disorder characterized by exocrine pancreatic insufficiency, bone marrow failure, skeletal abnormalities, and short stature. Pancytopenia can be a feature, although it's more commonly associated with neutropenia.
• Dyskeratosis Congenita: A rare genetic disorder characterized by the triad of mucocutaneous signs (oral leukoplakia, nail dystrophy, and reticulated skin hyperpigmentation), bone marrow failure, and an increased risk of malignancy. Pancytopenia can occur due to bone marrow failure.