Prenatal features of congenital peribronchial myofibroblastic tumor.

Here, we report a case of a congenital peribronchial myofibroblastic tumor (CPMT). A 34-year-old primigravida was referred to our hospital at 31 gestation weeks because of suspected congenital pulmonary airway malformation (CPAM). Fetal ultrasonography showed a mass measuring 4.6 × 4.0 × 3.9 cm with mixed high and low echogenicity in the left lung, which was associated with microvascular blood flow in the tumor. Fetal magnetic resonance imaging (MRI) revealed a low-intensity left lobe lung lesion on a T2-weighted image. These findings suggested that the mass was a CPAM with atypical hypointense findings on MRI T2-weighted images or a rare primary pulmonary tumor, such as a CPMT. Unfortunately, the fetus died in utero at 34 gestation weeks due to cardiovascular failure, which could have resulted from direct encasement of the great vessels or cardiac compression due to rapid tumor growth. The autopsy findings confirmed the diagnosis of CPMT. Primary pulmonary tumors, such as CPMT, are extremely rare lung diseases that develop in utero. These tumors often rapidly grow during pregnancy, resulting in intrauterine fetal death. However, if the patient survives surgical mass resection, the prognosis is good. Given the adverse outcomes observed in our case, careful fetal monitoring is required in case of suspected CPMT during the third trimester of pregnancy. Moreover, in case the well-being of the fetus cannot be assured, immediate delivery should be considered, even in the preterm period, followed by surgery.