Acquired cyclic thrombocytopenia-thrombocytosis with periodic defect of platelet function

The highs and lows of cyclic thrombocytopenia

Cyclic thrombocytopenia (CTP) is characterized by periodic platelet oscillation with substantial amplitude. Most CTP cases have a thrombocytopenic background and are often misdiagnosed as immune thrombocytopenia with erratically effective treatment choices. CTP also occurs during hydroxyurea treatment in patients with myeloproliferative diseases. While the aetiology of CTP remains uncertain, here we evaluate historical, theoretical and clinical findings to provide a framework for understanding CTP pathophysiology. CTP retains the intrinsic oscillatory factors defined by the homeostatic regulation of platelet count, presenting as reciprocal platelet/thrombopoietin oscillations and stable oscillation periodicity. Moreover, CTP patients possess pathogenic factors destabilizing the platelet homeostatic system thereby creating opportunities for external perturbations to initiate and sustain the exaggerated platelet oscillations. Beyond humoral and cell-mediated autoimmunity, we propose recently uncovered germline and somatic genetic variants, such as those of MPL, STAT3 or DNMT3A, as pathogenic factors in thrombocytopenia-related CTP. Likewise, the JAK2 V617F or BCR::ABL1 translocation that drives underlying myeloproliferative diseases may also play a pathogenic role in hydroxyurea-induced CTP, where hydroxyurea treatment can serve as both a trigger and a pathogenic factor of platelet oscillation. Elucidating the pathogenic landscape of CTP provides an opportunity for targeted therapeutic approaches in the future.

Cyclic Thrombocytopenia: A Rare Cause of Recurrent Thrombocytopenia

Cyclic thrombocytopenia (CTP) is a very rare hematological disorder that is characterized by periodic fluctuations in platelet counts. Diagnosis is generally delayed due to its similarity with immune thrombocytopenia (ITP). The pathophysiology is unknown and there are currently no guidelines for management. Many patients are usually treated for ITP initially prior to diagnosis. We describe a 67-year-old female with a history of multiple episodes of transient thrombocytopenia who presented to the hospital with another episode of thrombocytopenia. Her workup including HIV, hepatitis screening, vitamin B12, and folate was negative. She received a unit of platelet transfusion and was later observed in the hospital. Further review of her chart showed similar episodes in the past with spontaneous improvement. She was diagnosed with CTP. Her platelet count improved remarkably prior to discharge. In patients with recurrent fluctuation in their platelet count, CTP should be one of the differentials as this might prevent further unnecessary therapies.

How I manage cyclic thrombocytopenia

Cyclic thrombocytopenia (CTP) is a rare disease, which is characterized by periodic fluctuation of the platelet count. The pathogenesis of CTP is unknown and most likely heterogeneous. Patients with CTP are almost always misdiagnosed as having primary immune thrombocytopenia (ITP). The interval between ITP and CTP diagnosis can be many years. CTP patients often receive ITP-specific therapies including corticosteroids, thrombopoietin receptor agonists, rituximab, and splenectomy, which are followed by a transient increase in platelet count that is wrongly attributed to treatment effect with inevitable "relapse." CTP can be diagnosed by frequent platelet count monitoring, which reveals a typical pattern of periodic platelet cycling. An early diagnosis of CTP will prevent these patients from being exposed to possibly harmful therapies. The bleeding phenotype is usually mild and consists of mucocutaneous bleeding at the time when the platelet count is at its nadir. Severe bleeding from other sites can occur but is rare. Some patients respond to cyclosporine A or to danazol, but most patients do not respond to any therapy. CTP can be associated with hematological malignancies or disorders of the thyroid gland. Nevertheless, spontaneous remissions can occur, even after many years.

Idiopathic cyclic thrombocytopenia

Cyclic thrombocytopenia (CTP) is an uncommon disorder characterized by periodic fluctuations in platelet counts, typically resulting in episodes of thrombocytopenia alternating with normal platelet counts. While some CTP cases are associated with a primary hematologic disease, most are idiopathic. Patients with CTP are frequently misdiagnosed as idiopathic thrombocytopenic purpura (ITP) because CTP has clinical features very similar to ITP. When evaluating patients with suspected ITP, CTP should always be included in the differential diagnoses because CTP generally does not respond to standard ITP treatments, including corticosteroids, splenectomy, and intravenous immunoglobulin. Two clinical features relatively unique to CTP besides periodic thrombocytopenia are rebound thrombocytosis unrelated to recent splenectomy and platelet nadirs occurring during menses. When a diagnosis of CTP is made, patients must be offered a period of observation, as many may not require treatment. If treatment is clinically indicated, the literature suggests that hormonal therapy provides the best response.

Regulation of platelet production: the normal response to perturbation and cyclical platelet disease

An age-structured model for the regulation of platelet production is developed, and compared with both normal and pathological platelet production. We consider the role of thrombopoietin (TPO) in this process, how TPO affects the transition between megakaryocytes of various ploidy classes, and their individual contributions to platelet production. After the estimation of the relevant parameters of the model from both in vivo and in vitro data, we use the model to numerically reproduce the normal human response to a bolus injection of TPO. We further show that our model reproduces the dynamic characteristics of autoimmune cyclical thromobocytopenia if the rate of platelet destruction in the circulation is elevated to more than twice the normal value.

Danazol therapy in cyclic acquired amegakaryocytic thrombocytopenic purpura: a case report

Cyclic acquired amegakaryocytic thrombocytopenic purpura (AATP) is a rare disorder characterized by periodic fluctuations in the platelet counts due to a defect in the platelet production. We describe a 42-year-old female with cyclic AATP, in whom the cyclic fluctuations in the platelet counts ceased with danazol therapy. The pathogenesis of the disease and the possible mechanisms of danazol action have been reviewed.

Cyclical Neutropenia and Other Periodic Hematological Disorders: A Review of Mechanisms and Mathematical Models

Although all blood cells are derived from hematopoietic stem cells, the regulation of this production system is only partially understood. Negative feedback control mediated by erythropoietin and thrombopoietin regulates erythrocyte and platelet production, respectively, but the regulation of leukocyte levels is less well understood. The local regulatory mechanisms within the hematopoietic stem cells are also not well characterized at this point. Because of their dynamic character, cyclical neutropenia and other periodic hematological disorders offer a rare opportunity to more fully understand the nature of these regulatory processes. We review the salient clinical and laboratory features of cyclical neutropenia (and the less common disorders periodic chronic myelogenous leukemia, periodic auto-immune hemolytic anemia, polycythemia vera, aplastic anemia, and cyclical thrombocytopenia) and the insight into these diseases afforded by mathematical modeling. We argue that the available evidence indicates that the locus of the defect in most of these dynamic diseases is at the stem cell level (auto-immune hemolytic anemia and cyclical thrombocytopenia seem to be the exceptions). Abnormal responses to growth factors or accelerated cell loss through apoptosis may play an important role in the genesis of these disorders.

© 1998 by The American Society of Hematology.

Cyclical Neutropenia and Other Periodic Hematological Disorders: A Review of Mechanisms and Mathematical Models

Although all blood cells are derived from hematopoietic stem cells, the regulation of this production system is only partially understood. Negative feedback control mediated by erythropoietin and thrombopoietin regulates erythrocyte and platelet production, respectively, but the regulation of leukocyte levels is less well understood. The local regulatory mechanisms within the hematopoietic stem cells are also not well characterized at this point. Because of their dynamic character, cyclical neutropenia and other periodic hematological disorders offer a rare opportunity to more fully understand the nature of these regulatory processes. We review the salient clinical and laboratory features of cyclical neutropenia (and the less common disorders periodic chronic myelogenous leukemia, periodic auto-immune hemolytic anemia, polycythemia vera, aplastic anemia, and cyclical thrombocytopenia) and the insight into these diseases afforded by mathematical modeling. We argue that the available evidence indicates that the locus of the defect in most of these dynamic diseases is at the stem cell level (auto-immune hemolytic anemia and cyclical thrombocytopenia seem to be the exceptions). Abnormal responses to growth factors or accelerated cell loss through apoptosis may play an important role in the genesis of these disorders.

© 1998 by The American Society of Hematology.

Cyclic thrombocytopenia associated with IgM anti-GPIIb-IIIa autoantibodies

We studied a female patient with cyclic fluctuation in platelet count following splenectomy for autoimmune thrombocytopenia. The cyclical fluctuation appeared to be in phase with her menstrual cycle and her platelet count was low during menses. Bone marrow examinations performed at the peak as well as the bottom of the platelet count showed normal or increased numbers of megakaryocytes. The patient's platelet count increased rapidly after intravenous gamma-globulin (IVIgG) therapy, suggesting that a failure of platelet production is unlikely to account for the cycle. Platelet-associated IgM (PAIgM) was markedly elevated, whereas PAIgG was normal at any stage of the cycle. MACE assay demonstrated that PAIgM contained IgM anti-glycoprotein (GP) IIb-IIIa autoantibodies. Comparison between MACE assay using untreated and EDTA-treated platelets at 37 degrees C demonstrated that the platelet-associated IgM autoantibodies mainly recognized divalent cation-dependent conformation(s) of GPIIb-IIIa. No antibodies were, however, detected in her serum. The levels of IgM anti-GPIIb-IIIa showed an inverse relationship with the platelet count. In spite of the marked increase in platelet count after IVIgG, however, the levels of IgM anti-GPIIb-IIIa remained elevated. These findings suggest that platelet-associated IgM anti-GPIIb-IIIa autoantibodies are of pathogenic significance in this patient.