Differential Diagnosis for Thrombocytopenia in a 72-year-old Female

Single Most Likely Diagnosis

• Pseudothrombocytopenia: This condition, where platelets clump together in response to anticoagulants used in blood collection tubes, can lead to falsely low platelet counts. Given the mild decrease in platelet count and otherwise normal CBC, this is a plausible explanation.

Other Likely Diagnoses

• Mild Bone Marrow Suppression: Various medications, viral infections, or early stages of bone marrow disorders can cause mild thrombocytopenia. The patient's age and the mild nature of the thrombocytopenia make this a consideration.
• Early Myelodysplastic Syndrome (MDS): MDS can present with mild cytopenias, including thrombocytopenia, in the elderly. The consistent but mild decrease in platelet count warrants consideration of this diagnosis.
• Chronic Liver Disease: Liver disease can lead to thrombocytopenia due to splenic sequestration. However, other signs of liver disease would typically be present.

Do Not Miss Diagnoses

• Heparin-Induced Thrombocytopenia (HIT): Although less likely given the mild and consistent nature of the thrombocytopenia, HIT is a critical diagnosis to consider due to its potential for severe thrombotic complications. Recent heparin exposure would increase suspicion.
• Immune Thrombocytopenic Purpura (ITP): While ITP is more common in children, it can occur in adults. The diagnosis is often made based on isolated thrombocytopenia with an otherwise normal CBC.
• Leukemia or Lymphoma: These conditions can present with thrombocytopenia among other cytopenias. Although less likely with a normal CBC, they are critical to rule out.

Rare Diagnoses

• Thrombocytopenia with Absent Radius (TAR) Syndrome: Extremely rare and typically diagnosed in infancy, but could be considered in the differential if other signs are present.
• Wiskott-Aldrich Syndrome: Another rare condition, primarily affecting males, characterized by thrombocytopenia, eczema, and immunodeficiency.
• May-Hegglin Anomaly: A rare genetic disorder affecting platelet function and morphology, which could potentially present with thrombocytopenia.

Each of these diagnoses has a different set of implications for patient management and prognosis, highlighting the importance of a thorough diagnostic workup.