Adverse perinatal outcomes and recurrent perivillous fibrin deposition in Anti-Jo-1 antisynthetase syndrome: a case report

Antisynthetase syndrome (ASyS) is a rare idiopathic inflammatory myopathy characterised by the presence of anti-aminoacyl-tRNA synthetase antibodies, most commonly Anti-Jo-1. Pregnancy in women with ASyS is uncommon and carries significant obstetric risk. We report a case of a 36-year-old female with Anti-Jo-1–positive ASyS whose first pregnancy ended in intrauterine fetal death at term, with placental histology showing maternal floor infarction and massive perivillous fibrin deposition (MPVFD). In a subsequent pregnancy, she was managed with tocilizumab, hydroxychloroquine, cyclosporine, and low-dose prednisolone, along with low-dose aspirin (also used in the first pregnancy) and prophylactic enoxaparin sodium (newly introduced in the second). Maternal disease remained clinically quiescent throughout early pregnancy, until a mild articular flare occurred in the second trimester. Following subsequent stabilisation, fetal growth restriction was detected in the third trimester, leading to emergency caesarean section at 33+5 weeks for fetal distress. The neonate was healthy and discharged. Placental histology revealed extensive perivillous fibrin deposition not meeting MPVFD criteria. This case documents recurrent perivillous fibrin deposition across two consecutive pregnancies in Anti-Jo-1 ASyS, with divergent perinatal outcomes observed. The findings are consistent with the possibility that immune-mediated placental injury may be associated with adverse events, even when maternal muscle disease appeared clinically quiescent and biochemical markers were normal. Placental pathology provided additional information for risk stratification and supported the use of intensified surveillance and preventive strategies. This report supports considering systematic placental histopathology and early multidisciplinary surveillance may help inform the management of pregnancies in women with Anti-Jo-1 ASyS.