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Prior studies have suggested that immune thrombotic thrombocytopenic purpura (iTTP) may display seasonal variation; however, methodologic limitations and sample sizes have diminished the ability to perform a rigorous assessment. This 5-year retrospective study assessed the epidemiology of iTTP and determined whether it displays a seasonal pattern. Patients with both initial and relapsed iTTP (defined as a disintegrin and metalloprotease with thrombospondin type motifs 13 activity <10%) from 24 tertiary centers in Australia, Canada, France, Greece, Italy, Spain, and the US were included. Seasons were defined as: Northern Hemisphere-winter (December-February); spring (March-May); summer (June-August); autumn (September-November) and Southern Hemisphere-winter (June-August); spring (September-November); summer (December-February); autumn (March-May). Additional outcomes included the mean temperature in months with and without an iTTP episode at each site. A total of 583 patients experienced 719 iTTP episodes. The observed proportion of iTTP episodes during the winter was significantly greater than expected if equally distributed across seasons (28.5%, 205/719, 25.3%-31.9%; p = .03). Distance from the equator and mean temperature deviation both positively correlated with the proportion of iTTP episodes during winter. Acute iTTP episodes were associated with the winter season and colder temperatures, with a second peak during summer. Occurrence during winter was most pronounced at sites further from the equator and/or with greater annual temperature deviations. Understanding the etiologies underlying seasonal patterns of disease may assist in discovery and development of future preventative therapies and inform models for resource utilization., (© 2024 The Author(s). American Journal of Hematology published by Wiley Periodicals LLC.)

Cryofibrinogenemia is a rare disorder in which plasma, not serum, forms a cryoprecipitate. Patients with cryofibrinogenemia may be asymptomatic, or they may have painful ulcers, purpura, livedo reticularis, Raynaud phenomenon, perniosis of the extremities, thrombosis, and arthralgia. Cryofibrinogenemia may be primary or secondary to an underlying disorder such as connective tissue disease, malignancy, infection, drugs, or thromboembolic disease. Here, we present a 41-year-old woman with a pancreatic neuroendocrine tumor who underwent a Whipple procedure in 2003 followed by 2 liver transplants for hepatic metastases. Three years posttransplant, we discovered a biopsy-proven metastatic lesion in her femur. Five years posttransplant, she developed acute, severe pain in both feet, and was found to have cryofibrinogenemia despite immunosuppression post-transplant. Testing for connective tissue diseases and hematologic malignancy were negative. She was treated with high-dose prednisone, which completely resolved her symptoms. We also conducted a review of the literature via a PubMed search to summarize the association of cryofibrinogenemia with malignancy and treating cryofibrinogenemia with corticosteroids. Our study is the first reported case of cryofibrinogenemia that developed secondary to a neuroendocrine tumor posttransplant. Our report suggests that cryofibrinogenemia may occur despite immunosuppression adequate to prevent graft rejection, and that high-dose corticosteroids are an effective treatment for posttransplant cryofibrinogenemia.