Tuberculosis-associated Immune Thrombocytopenia: A Case Report

Al Argan, Reem J.; Al Elq, Abdulmohsen H.

Thrombocytopenia with TB can occur because of a defect in platelet production related to bone marrow infiltration, as a side effect of anti-TB therapy, splenomegaly or concomitant histiophagocytosis, thrombotic thrombocytopenic purpura, DIC or immune-mediated platelet destruction. The initial response to IVIG and steroids in this patient supports the immune bases of TB-induced thrombocytopenia. The mechanism of TB-related ITP remains unclear, although it has been postulated that the activation of B lymphocytes by Mycobacterium tuberculosis leads to the production of antiplatelet antibodies or that M. tuberculosis may share antigen with the platelets, leading to the production of antiplatelet antibodies. [8] The antiplatelet antibodies were not measured in this patient, as in the 2011 American Society of Hematology guidelines, the evidence to recommend measuring antiplatelet antibodies during diagnosis of ITP is insufficient. [9] As stated above, the occurrence of ITP during TB infection is exceedingly rare and only few cases have been reported in the literature. In a study from Saudi Arabia comprising 846 cases of active TB, only 9 (1%) presented with ITP as the sole presentation. Of these 9 cases, 3 had pulmonary TB, 3 abdominal abscess or lymphadenitis and 3 disseminated (miliary) TB. All patients had purpura, the platelet count varied between 4 and 21 × 10 9 /L and the bone marrow showed increased megakaryocytes. [3] In a review by Tsuro et al., [10] pulmonary TB constituted 31% of all ITP cases, TB lymphadenitis 31% and miliary TB 27%. Most patients were of Middle Eastern and Asian descent. Similarly, the patient in this report is from an Asian descent and TB lymphadenitis was the initial presentation but was later found to have lung involvement.