Case Report: Confirmed and suspected heparin-induced thrombocytopenia during therapeutic plasma exchange in neuromyelitis optica spectrum disorder: a single-centre case series.

Neuromyelitis optica spectrum disorder (NMOSD) is a B-cell-mediated autoimmune disease associated with aquaporin-4 (AQP4-IgG) antibodies in which patients may require anticoagulation, including heparin for venous thromboembolism prophylaxis, thereby exposing them to a risk of heparin-induced thrombocytopenia (HIT), an immune-mediated complication caused by antibodies directed against PF4-heparin complexes. Whether anti-AQP4-mediated autoimmunity contributes to susceptibility to anti-PF4/heparin immune responses warrants further investigation. Four cases of suspected or confirmed HIT in patients with NMOSD are presented, together with a review of the current literature. In our NMOSD cohort (n=90), 24 patients underwent therapeutic plasma exchange (TPE), among whom HIT was suspected in four cases (16,7% suspected and 8.3% immunoassay positive). These findings underscore the need for vigilance regarding HIT and thromboembolic complications in NMOSD patients undergoing relapse treatment with TPE. Strategies for the safe continuation of TPE using non-heparin anticoagulation and considerations for outpatient management are also addressed. Awareness of this potential association may facilitate earlier recognition and appropriate management in clinical practice.