Extreme Reactive Thrombocytosis in Probable Tuberculous Meningitis Mimicking a Myeloproliferative Neoplasm: A Case Report

Abstract

Background: Extreme thrombocytosis is uncommon in infectious disease and may mimic a myeloproliferative neoplasm, creating a diagnostic and management challenge.

Case presentation: A 23-year-old woman presented with several weeks of headache, fever and recurrent vomiting, followed by progressive alteration in sensorium. Her platelet count was 1716 × 10⁹/L. Peripheral blood smear showed marked thrombocytosis without blasts or dysplasia. Brain magnetic resonance imaging demonstrated multiple ring-enhancing lesions with surrounding oedema and meningeal enhancement, and cerebrospinal fluid showed lymphocytic pleocytosis. In the absence of microbiological confirmation, a working diagnosis of probable tuberculous meningitis with intracranial tuberculomas was made. She received antituberculous therapy, adjunctive corticosteroids and supportive care; cytoreductive, antiplatelet and anticoagulant therapy were not initiated. Platelet counts fell to 420 × 10⁹/L at three weeks and 222 × 10⁹/L at two months, accompanied by clinical improvement.

Conclusion: Extreme thrombocytosis may occur as a reactive phenomenon in probable tuberculous meningitis and can closely resemble a myeloproliferative neoplasm. Careful clinical assessment and serial platelet monitoring may help avoid unnecessary invasive investigation or cytoreductive treatment when a reactive cause is strongly supported.