Thrombocytopenia in hospitalized patients: approach to the patient with thrombotic microangiopathy

Diagnosis of thrombotic microangiopathy in preeclampsia in the common marmoset (Callithrix jacchus) and treatment by cesarean section

A pregnant common marmoset (Callithrix jacchus) showed tachypnea, hypothermia, and anorexia at close to the expected delivery date. Severe anemia and thrombocytopenia, schistocytes, and high levels of LDH and D-dimer were observed. Three days after the onset of clinical signs, a cesarean section was conducted due to stillbirth. Marmoset immediately recovered after surgery, and the abnormal CBC and blood chemistry parameters before surgery returned to the normal ranges. Diagnosis of pregnancy-associated thrombotic microangiopathy was made because removal of infant and placenta is curative. To the best of our knowledge, this is the first case report of thrombotic microangiopathy in a marmoset with preeclampsia.

How I treat microangiopathic hemolytic anemia in patients with cancer

Microangiopathic hemolytic anemia (MAHA) with thrombocytopenia, suggests a thrombotic microangiopathy (TMA), linked with thrombus formation affecting small or larger vessels. In cancer patients, it may be directly related to the underlying malignancy (initial presentation or progressive disease), to its treatment, or a separate incidental diagnosis. It is vital to differentiate incidental thrombotic thrombocytopenia purpura or atypical hemolytic uremic syndrome in cancer patients presenting with a TMA, as they have different treatment strategies, and prompt initiation of treatment impacts outcome. In the oncology patient, widespread microvascular metastases or extensive bone marrow involvement can cause MAHA and thrombocytopenia. A disseminated intravascular coagulation (DIC) picture may be precipitated by sepsis or driven by the cancer itself. Cancer therapies may cause a TMA, either dose-dependent toxicity, or an idiosyncratic immune-mediated reaction due to drug-dependent antibodies. Many causes of TMA seen in the oncology patient do not respond to plasma exchange and, where feasible, treatment of the underlying malignancy is important in controlling both cancer-TMA or DIC driven disease. Drug-induced TMA should be considered and any putative causal agent stopped. We will discuss the differential diagnosis and treatment of MAHA in patients with cancer using clinical cases to highlight management principles.

Evans' Syndrome: From Diagnosis to Treatment

Evans' syndrome (ES) is defined as the concomitant or sequential association of warm auto-immune haemolytic anaemia (AIHA) with immune thrombocytopenia (ITP), and less frequently autoimmune neutropenia. ES is a rare situation that represents up to 7% of AIHA and around 2% of ITP. When AIHA and ITP occurred concomitantly, the diagnosis procedure must rule out differential diagnoses such as thrombotic microangiopathies, anaemia due to bleedings complicating ITP, vitamin deficiencies, myelodysplastic syndromes, paroxysmal nocturnal haemoglobinuria, or specific conditions like HELLP when occurring during pregnancy. As for isolated auto-immune cytopenia (AIC), the determination of the primary or secondary nature of ES is important. Indeed, the association of ES with other diseases such as haematological malignancies, systemic lupus erythematosus, infections, or primary immune deficiencies can interfere with its management or alter its prognosis. Due to the rarity of the disease, the treatment of ES is mostly extrapolated from what is recommended for isolated AIC and mostly relies on corticosteroids, rituximab, splenectomy, and supportive therapies. The place for thrombopoietin receptor agonists, erythropoietin, immunosuppressants, haematopoietic cell transplantation, and thromboprophylaxis is also discussed in this review. Despite continuous progress in the management of AIC and a gradual increase in ES survival, the mortality due to ES remains higher than the ones of isolated AIC, supporting the need for an improvement in ES management.

Expert consensus on the diagnosis and treatment of thrombocytopenia in adult critical care patients in China

Thrombocytopenia is a common complication of critical care patients. The rates of bleeding events and mortality are also significantly increased in critical care patients with thrombocytopenia. Therefore, the Critical Care Medicine Committee of Chinese People's Liberation Army (PLA) worked with Chinese Society of Laboratory Medicine, Chinese Medical Association to develop this consensus to provide guidance for clinical practice. The consensus includes five sections and 27 items: the definition of thrombocytopenia, etiology and pathophysiology, diagnosis and differential diagnosis, treatment and prevention.

Comparison between optical microscopy and the Sysmex XN-3000 for schistocyte determination in patients suspected of having schistocytosis

Background and aims

Diagnosis of thrombotic microangiopathy (TMA) relies on microscopic schistocyte determination by an experienced microscopist. In addition, schistocytes can be found in non‐TMA–related disorders such as thalassaemia. We aimed to compare the accuracy of the automated haematology analyser Sysmex XN‐3000 for schistocyte detection, to that of the microscopy approach, in patients suspected of having schistocytosis.

Methods

Consecutive blood samples were collected between April 2016 and March 2017 at Siriraj Hospital, Mahidol University, Bangkok, Thailand. Specimens were collected from adults with suspected TMA or with thalassaemia trait and/or disease. All blood samples were examined by both microscopy and the analyser. Samples were considered to be positive for schistocytes (ie, schistocytosis) if they had a schistocyte count ≥1% by microscopy. The analyser's ability to determine schistocytosis was assessed by receiver operating characteristic (ROC) curve. Sensitivity, specificity, positive (PPV), and negative predictive value (NPV) of an appropriate cut‐off point were calculated, with manual microscopy as the standard. Quantitative agreement in schistocyte counts between the two approaches was assessed using 95% limits of agreement, Bland‐Altman plots, intraclass correlation coefficient, and concordance correlation coefficient.

Results

Ninety‐seven blood samples (62 suspected TMA and 35 thalassaemia) were collected. ROC curve analysis of the analyser for determining schistocytosis showed an area under the curve of 0.803 (95% confidence interval, 0.689‐0.917, P < 0.001). A cut‐off point of 0.6% yielded 86.1% sensitivity, 77.8% specificity, 94.4% PPV, and 56.0% NPV. The automated schistocyte count did not quantitatively agree with schistocyte counts by microscopy, neither in all blood specimens (mean of difference: −1.09; 95% limits of agreement, −11.9 to 9.7) nor in the subgroups (TMA, −0.88; 95% limits of agreement, −6.60 to 4.84; thalassaemia, −2.4; 95% limits of agreement, −14.10 to 9.30). The differences in the estimation of fragmented red blood cells between the methods tended to increase at higher schistocyte counts.

Conclusion

Sysmex XN‐3000 can be used for qualitative measurement of schistocytosis, but should not be used as a quantitative tool for schistocyte counting. Improvements are needed before this analyser's schistocyte detection feature can be recommended for use in clinical practice.

Microangiopathy in Cancer: Causes, Consequences, and Management

Thrombotic microangiopathy (TMA) is a syndrome involving fragmentation haemolysis, thrombocytopenia, and thrombosis. A range of disorders including cancer may have TMA as a clinical manifestation. TMA in cancer may be caused by several mechanisms, including systemic microvascular metastases, but may also be due to extensive bone marrow involvement with cancer or secondary necrosis. Chemotherapeutic agents may also cause associated TMA through a range of different mechanisms. Gemcitabine, platinum-based drugs, mitomycin C, and proteasome inhibitors are known to cause TMA in cancer patients. Transplant-associated TMA (TA-TMA) may affect either solid organ or HSCT patients. TA-TMA remains a difficult complication to address due to its high mortality rate, lack of standard diagnostic criteria, and limited therapeutic options. The challenge of cancer-associated TMA is furthered by the fact that plasma exchange is ineffective in its management.