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The Community Oncologist

Disseminated Malignancy Misdiagnosed as Thrombotic Thrombocytopenic Purpura: A Report of 10 Patients and a Systematic Review of Published Cases

Hematology-Oncology Section, Department of Medicine, College of Medicine, Department of Biostatistics and Epidemiology, College of Public Health, The University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, USA

Key Words. Cancer • Thrombotic thrombocytopenic purpura • Hemolytic-uremic syndrome • Microangiopathic hemolytic anemia

Correspondence: James N. George, M.D., The University of Oklahoma Health Sciences Center, Hematology-Oncology Section, Room CHB 358, P.O. Box 26901, Oklahoma City, Oklahoma 73190, USA. Telephone: 405-271-4222; Fax: 405-271-6444; e-mail: james-george{at}ouhsc.edu

Background. Patients with disseminated malignancy who present with microangiopathic hemolytic anemia and thrombocytopenia may be misdiagnosed as thrombotic thrombocytopenic purpura (TTP), resulting in inappropriate plasma exchange treatment, a procedure with major risk, and delay of appropriate chemotherapy.

Purpose. To assess clinical features that may distinguish occult disseminated malignancy from TTP.

Patients and methods. We report the 17-year experience of The Oklahoma TTP-Hemolytic-Uremic Syndrome (HUS) Registry (1989–2005) and a systematic review of previously published case reports.

Results. Ten of 351 patients in the Oklahoma Registry who were initially diagnosed with TTP and treated with plasma exchange were subsequently discovered to have disseminated malignancy. Only one patient had a history of cancer. In these 10 patients, neurologic abnormalities, hematocrit, platelet count, and serum creatinine were not different from the 133 concurrent patients with idiopathic TTP. Patients with disseminated malignancy had a longer duration of symptoms, more frequent presence of respiratory symptoms, higher lactate dehydrogenase levels, and more often failed to respond to plasma exchange treatment. Diagnosis of malignancy was made by bone marrow biopsy in six patients but not until autopsy in two patients. A systematic literature review identified 19 additional patients, reported from 1965 to 2005, in whom TTP or HUS was initially suspected and systemic malignancy was subsequently discovered. Fourteen different malignant disorders were diagnosed in these 29 patients.

Conclusions. Occult disseminated malignancy may mimic TTP. A search for systemic malignancy, including a bone marrow biopsy, is appropriate when patients with TTP have atypical clinical features or fail to respond to plasma exchange.