Daisuke Kobayashi, Sayuri Takamura, Shunsuke Sakai, Yoko Wada, Eriko Hasegawa, Ayako Wakamatsu, Yukiko Nozawa, Hiroe Sato, Takeshi Kuroda, Suguru Yamamoto
Pregnancy after anti-melanoma differentiation-associated gene 5 (anti-MDA5) antibody-positive dermatomyositis-associated interstitial lung disease is rarely described, and preconception management remains uncertain. A 29-year-old woman presented with fever, arthralgia, cough, characteristic Gottron's and inverse Gottron's papules, normal muscle enzyme levels, mild interstitial lung abnormalities on high-resolution computed tomography, and positivity for anti-melanoma differentiation-associated gene 5 antibody. Because of the potential risk of rapid pulmonary deterioration, she received prednisolone, a calcineurin inhibitor, and intravenous cyclophosphamide, followed by maintenance immunosuppression. Mycophenolate mofetil was discontinued as part of preconception planning 24 months after disease onset. After two biochemical pregnancies that ended before ultrasonographic confirmation of a gestational sac, a subsequent pregnancy was confirmed approximately 36 months after disease onset while she was receiving prednisolone 10 mg/day and tacrolimus. Pregnancy was not complicated by relapse of dermatomyositis or interstitial lung disease, hypertensive disorder, gestational diabetes, fetal growth restriction, or non-reassuring fetal status. She delivered a healthy female infant at 38 weeks and 3 days of gestation by vaginal delivery. At more than 4 years postpartum, she remained relapse-free, and the antibody remained negative. This case suggests that planned pregnancy may be feasible in carefully selected patients after sustained preconception disease control, discontinuation of teratogenic drugs, and continuation of pregnancy-compatible immunosuppression under multidisciplinary surveillance; serial anti-MDA5 antibody measurements may provide adjunctive information when interpreted alongside clinical, pulmonary function, and imaging assessments.