Femoral pseudotumor secondary to injury in a patient with idiopathic thrombocytopenic purpura: Case report

RATIONALE: Idiopathic thrombocytopenic purpura (ITP) is the condition of having a low platelet count of unknown causes and is a poorly understood acquired hemorrhagic disease involving destruction of platelets in the reticuloendothelial system induced by antiplatelet antibodies. Patients with ITP can have traumatic intra-articular, intraosseous or soft tissue hemorrhage which may present as a rare intraosseous pseudotumor on medical imaging. PATIENT CONCERNS: A 30-year old male patient had complaint of pain in the right leg for 1 year. Laboratory test revealed a much lower platelet count (3–12 × 10(9)/L). DIAGNOSES: Radiography and computed tomography showed expansive bone destruction in the distal segment of the right femur, and magnetic resonance imaging revealed heterogeneous signal intensity in the lesion. Lesion curettage and pathology showed an expansion cyst with a really thin cortical bone shell containing serum-like red liquid and some sediment-like deposit. Consequently, the diagnosis of a pseudotumor was confirmed. INTERVENTIONS: Lesion curettage and bone graft surgery were performed, and 8 units of platelet were transfused to the patient. Giant cell reaction was found on the shell of the lesion, but no tumor cell was found on pathological examination. OUTCOMES: The platelet count was 308 × 10(9)/L 5 days after operation, and the clotting time was normal. At 6 month follow-up after lesion curettage, the patient remained normal with no deterioration in the lesion site. CONCLUSION: The diagnosis of a pseudotumor of ITP relies mainly on imaging findings of the lesion and, in particular, knowledge of the underlying bleeding disorders. Radiologist and pathologist should be aware of the characteristics of this rare complication of ITP and other bleeding disorders like hemophilia in order to avoid misinterpretation of the lesion as a tumor or infection disease.