Risk of venous thromboembolism in patients with mycosis fungoides and parapsoriasis: A Danish nationwide population-based cohort study.

BACKGROUND: Mycosis fungoides (MF) and parapsoriasis are characterized by malignant proliferation and chronic inflammation, which may affect the risk for venous thromboembolism (VTE).

OBJECTIVES: To examine the risk for VTE in patients with MF and parapsoriasis.

METHODS: We conducted a nationwide population-based cohort study in Denmark to examine the relative risk (RR) of VTE in 525 patients with MF and 634 patients with parapsoriasis compared with that in sex- and age-matched controls from the general population.

RESULTS: In patients with MF, the 10-year absolute risk for VTE was 3.4% (95% confidence interval [CI], 2.0-5.4). The adjusted RRs were 2.41 (95% CI, 1.49-3.90) for VTE and 4.01 (95% CI, 2.16-7.46) for pulmonary embolism. Notably, within the first 5 years after diagnosis with MF, the RR of pulmonary embolism was increased 6.7-fold (to 6.71 [95% CI, 2.86-15.72]). Patients with parapsoriasis had a 2.7-fold increased RR of VTE (to 2.67 [95% CI, 1.32-5.40]) in the absence of other established VTE risk factors.

LIMITATIONS: We had no information regarding disease stage of MF and prescribed drugs.

CONCLUSION: Patients with MF and parapsoriasis had an increased RR of VTE, although the absolute risk remained low. These findings should increase awareness of comorbidities in patients with MF and parapsoriasis.