Thrombocytosis: Symptoms and Differential Diagnosis

Thrombocytosis refers to an elevated platelet count in the blood, which can be either primary (due to a bone marrow disorder) or secondary (reactive, due to another condition). The differential diagnosis for thrombocytosis can be organized into the following categories:

• Single Most Likely Diagnosis
  • Reactive thrombocytosis: This is the most common cause of thrombocytosis, often seen in response to acute or chronic inflammation, infection, trauma, or iron deficiency. It is justified as the single most likely diagnosis due to its high prevalence and the common occurrence of these underlying conditions.
• Other Likely Diagnoses
  • Essential thrombocythemia: A myeloproliferative neoplasm characterized by the overproduction of platelets. It's a likely diagnosis in patients with a sustained elevation of platelet count without an apparent secondary cause.
  • Iron deficiency anemia: Chronic iron deficiency can lead to an increase in platelet production. This condition is common and can easily be overlooked as a cause of thrombocytosis.
  • Chronic inflammatory conditions (e.g., rheumatoid arthritis, inflammatory bowel disease): These conditions can stimulate the production of platelets as part of the inflammatory response.
• Do Not Miss Diagnoses
  • Polycythemia vera: Another myeloproliferative neoplasm that can present with thrombocytosis, along with an increase in red blood cells and sometimes white blood cells. Missing this diagnosis could lead to significant morbidity due to the risk of thrombotic events.
  • Myelodysplastic syndromes: A group of disorders caused by poorly formed or dysfunctional blood cells, which can sometimes present with thrombocytosis. Early detection is crucial for management and potential cure.
  • Malignancies: Certain cancers can cause thrombocytosis, either through direct bone marrow involvement or through paraneoplastic syndromes. Missing a malignancy could have fatal consequences if not promptly treated.
• Rare Diagnoses
  • Primary myelofibrosis: A myeloproliferative neoplasm characterized by the replacement of bone marrow with fibrotic tissue, which can lead to thrombocytosis in its early stages.
  • Chronic myeloid leukemia (CML): Although CML more commonly presents with leukocytosis, thrombocytosis can be an initial finding in some cases.
  • Splenectomy: The removal of the spleen can lead to thrombocytosis due to the spleen's role in sequestering platelets. This is a rare cause but should be considered in patients with a history of splenectomy.