Pulmonary Tumor Thrombotic Microangiopathy

Pulmonary tumor thrombotic microangiopathy (PTTM) is a rare clinical entity where tumor cell embolisms in pulmonary circulation induce thrombotic microangiopathy (TMA), respiratory failure, and subacute cor pulmonale. We describe 3 cases of PTTM that presented as the initial manifestation of metastatic gastric adenocarcinoma with TMA and pulmonary infiltrates. All 3 cases had similar clinical and laboratory features, which included moderate thrombocytopenia without renal failure, hemolysis with extremely high serum lactate dehydrogenase levels, leukoerythroblastosis in peripheral blood smear, altered coagulation tests, lymphadenopathies, and interstitial pulmonary infiltrates. All patients died within 2 weeks of diagnosis. Two cases were initially misdiagnosed as idiopathic thrombotic thrombocytopenic purpura and treated with plasma exchange with no response. One patient had bone marrow infiltration by malignant cells. Autopsies revealed PTTM associated with gastric disseminated adenocarcinoma (signet-ring cell type in 2 patients and poorly differentiated type in 1). PTTM should be considered in the differential diagnosis of patients with fulminant microangiopathic hemolytic anemia, such as atypical thrombotic thrombocytopenic purpura, mainly those with pulmonary infiltrates, disseminated intravascular coagulation, or Trousseau syndrome. (Medicine 2014;93: 359–363) Abbreviations: aPTT = activated partial thromboplastin time, ADAMTS-13 = a desintegrin and metalloprotease with a thrombospondin type 1 motif, member 13, CT = computed tomography, DAT = direct antiglobulin test, DIC = disseminated intravascular coagulation, FDPs = fibrin degradation products, ICU = intensive care unit, LDH = lactate dehydrogenase, LOS = length of stay, MAHA = microangiopathic hemolytic anemia, NHL = non-Hodgkin lymphoma, PT = prothrombin time, PTTM = pulmonary tumor thrombotic microangiopathy, TMA = thrombotic D, PhD, Arturo P hD, D, PhD, and Josep M. Nicolás, MD, PhD INTRODUCTION P ulmonary tumor thrombotic microangiopathy (PTTM) is a rare clinical entity where tumor cell embolisms in pulmonary circulation induce thrombotic microangiopathy (TMA), respiratory failure, and subacute cor pulmonale. TMA is a disorder characterized by thrombocytopenia, Coombs negative microangiopathic hemolytic anemia (MAHA), and variable degrees of organ dysfunction. Diagnosis of PTTM is challenging. It is often misdiagnosed as thrombotic thrombocytopenic purpura (TTP), and the patient is started on plasma exchange therapy. However, such treatment is ineffective and the disease usually progresses quickly to a fatal outcome. Therefore, prompt etiologic diagnosis is very important because the only chance for the patient is to achieve a response to tumor-specific chemotherapy. We present hereby 3 patients with PTTM presenting with TMA and lung involvement admitted to the same hospital. We note that these patients presented features of TTP but with atypical characteristics that can help to shape the differential diagnosis. We also address other potential differential diagnoses. PATIENTS AND METHODS We describe 3 cases of PTTM that presented as the initial manifestation of metastatic gastric adenocarcinoma with TMA and pulmonary infiltrates. All 3 patients had similar clinical and laboratory features and were admitted to the intensive care unit (ICU) of the same hospital due to the severity and clinical complications during the hospitalization. All patients died within 2 weeks of diagnosis. As this is a retrospective and descriptive study with no intervention, and figures do not show identifiable patients, institutional review board approval and informed consents were waived.