Introduction Atypical sites for thrombosis include deep vein thrombosis (DVT) of the upper extremity (UE-DVT), splanchnic vein thrombosis (SVT), and cerebral venous sinus thrombosis (CVST). In addition to specific pathogenic factors, their underlying mechanisms share similarities with typical venous thromboembolism (VTE), namely, DVT of the lower extremity and/or pulmonary embolism, but are less understood.

Methods Records of unselected patients with a history of typical VTE (n = 2,011), UE-DVT (n = 117), SVT (n = 83), and CVST (n = 82), who were referred to the Institute in Bonn for ambulatory thrombophilia testing, were retrospectively analyzed. Acquired and hereditary thrombosis risk factors were comparatively assessed.

Results UE-DVT was characterized by a high rate (50.4%) of site-specific acquired risk factors. Compared with typical VTE, SVT was more frequently associated with systemic inflammation, infection, or malignancy (2.2 vs. 12.0%, p = 3·10−8) and the JAK2 V617F mutation was present in 16.9%. In CVST compared with typical VTE, demographics and higher rates of oral contraception (43.2 vs. 57.6%, p = 0.011) and pregnancy (4.2 vs. 10.9%, p = 0.012) suggest a significant hormonal influence on etiology. While the prevalence of inhibitor deficiencies and factor V Leiden mutation did not differ between cohorts, the prevalence of F2 20210G > A was higher in SVT (15.7%, p = 0.003) and CVST (15.9%, p = 0.003) than in typical VTE (7.0%).

Conclusion The cohorts with thrombosis in atypical sites showed distinctive patterns of acquired risk factors. Further studies are warranted to provide additional mechanistic insight into the role of hormonal influence in CVST and the contribution of F2 20210G > A to the development of SVT and CVST.

H.R. and S.R. are joint senior authors. H.R. and S.R. conceived and designed the study; D.K., H.L.M, N.S., and S.R. collected the data; D.K., H.R., and S.R. analyzed the data. D.K., H.R., and S.R. drafted and edited the manuscript. All authors revised the manuscript, agreed with its content, and approved of submission.

J.O. has received research funding from Bayer, Biotest, CSL Behring, Octapharma, Pfizer, Swedish Orphan Biovitrum, and Takeda; consultancy, speakers bureau, honoraria, scientific advisory board, and travel expenses from Bayer, Biogen Idec, BioMarin, Biotest, Chugai Pharmaceutical Co., Ltd., CSL Behring, Freeline, Grifols, LFB, Novo Nordisk, Octapharma, Pfizer, F. Hoffmann-La Roche Ltd., Sanofi, Spark Therapeutics, Swedish Orphan Biovitrum, and Takeda. The other authors declare no competing financial interests.

*Heiko Rühl and Sara Reda are joint senior authors.

Received: 09 April 2024

Accepted: 14 May 2024

Article published online:
26 June 2024

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