Fetal hemothorax due to intrapleural rupture of a small anterior thoracic lymphatic malformation: a case report

Abstract Background Fetal pleural effusion is usually chylous, whereas hemothorax is considerably rarer. Trauma, iatrogenic complications, and rupture of intrathoracic tumors have been reported as causes of fetal hemothorax. Lymphatic malformations often enlarge during the fetal period; however, these benign lesions may regress spontaneously after birth or be managed with sclerotherapy. Accurate prenatal diagnosis is therefore crucial for determining whether fetal intervention or postnatal management is the most appropriate strategy. Here, we present a rare case of a fetus with hemothorax presumably caused by the rupture of a small anterior chest wall lymphatic malformation that progressed to hydrops fetalis. Case presentation A Japanese woman in her 30 s (gravida 2, para 1) was referred at 26 weeks of gestation after bloody pleural fluid was obtained by thoracentesis at another hospital. On admission, ultrasonography showed right pleural effusion without ascites or subcutaneous edema. Additionally, there was a small heterogeneous echogenic region in the anterior chest wall without detectable blood flow, although its clinical significance was initially unclear. Fetal magnetic resonance imaging demonstrated pleural fluid with signal characteristics consistent with hemothorax and identified a small anterior chest wall cystic lesion, suggestive of a lymphatic malformation. Because the pleural effusion was hemorrhagic, thoracoamniotic shunting was avoided owing to concerns regarding rebleeding and potential worsening of fetal anemia. At 27 weeks and 6 days, an emergency cesarean section was performed for worsening hydrops. The infant required immediate intubation, chest drainage, and blood transfusion. Postnatal imaging confirmed an anterior chest wall lymphatic malformation extending toward the mediastinum. The lesion did not require surgical or sclerosing therapy and showed spontaneous regression during follow-up. Neurodevelopmental assessment was within the normal range at a corrected age of 18 months. Conclusion This case demonstrated the importance of detailed imaging studies, including magnetic resonance imaging, for the diagnosis of pleural effusion and small anterior chest lesions. In cases of tumor-associated fetal hemothorax caused by benign lesions such as lymphatic malformations, early delivery followed by neonatal management may represent a reasonable alternative to fetal intervention.