C51-10 Mimicking Malignancy: A Rare Presentation of Immune Thrombocytopenia in a Healthy Young Adult

Introduction Immune thrombocytopenia (ITP) typically causes isolated thrombocytopenia with mucocutaneous bleeding. However, transient blast-appearing cells are rare and may prompt an urgent leukemia evaluation. We report a severe relapse of ITP in a healthy young adult, with dramatic oral hemorrhagic bullae and blast-like peripheral forms, ultimately requiring bone marrow biopsy to exclude malignancy. An incidental chlamydia infection suggests infection-triggered exacerbation. Description of Case A 26-year-old man presented with painful black hemorrhagic bullae on the buccal mucosa and lip, petechiae on his legs, and scattered ecchymoses. He denied fever, weight loss, lymphadenopathy, or splenomegaly. Platelet count was 1 × 10³/µL. Peripheral smear showed no schistocytes. LDH was mildly elevated; Coombs was negative. Infectious testing (HIV, HBV, HCV, EBV, CMV, syphilis) and autoimmune studies (ANA, dsDNA, Smith) were negative except for asymptomatic Chlamydia trachomatis. He received IVIG and dexamethasone with platelets rising to 50 × 10³/µL by day 3. Ten days post-discharge, identical mucosal bleeding recurred with platelets again at 1 × 10³/µL. This time, peripheral smear demonstrated blast-like cells concerning for acute leukemia. Bone marrow biopsy revealed a normocellular marrow with abundant megakaryocytes, no fibrosis, no increase in blasts, and normal cytogenetics and flow cytometry. He was treated with repeat IVIG and transitioned to a prednisone taper. Platelets recovered to 24 × 10³/µL by day 3 and 250 × 10³/µL by day 10. He never developed lymphadenopathy, organomegaly, or systemic symptoms, and bullae resolved completely. Discussion This case demonstrates how severe ITP can clinically and hematologically mimic acute leukemia. Hemorrhagic oral bullae and transient blast-appearing forms on smear created a high-risk diagnostic dilemma, but bone marrow evaluation confirmed peripheral platelet destruction rather than a primary marrow process. The patient’s silent chlamydia infection raises the possibility of infectious triggers for relapse. In relapsing or atypical ITP especially with dramatic mucosal bleeding or malignant-appearing smears early bone marrow biopsy is essential to avoid misdiagnosis and guide appropriate therapy. This abstract is funded by: None