Benign but fatal. A case of a newborn with congenital osteochondroma.

Osteochondroma is one of the most frequent benign bone tumors in children. Its incidence is hard to determine because this tumor usually is asymptomatic. These tumors may present as solitary, nonhereditary lesions or as hereditary multiple osteochondromas that are inherited in an autosomal dominant manner. Although osteochondromas are usually asymptomatic, significant symptoms may occur because of complications such as bone fracture, bone deformation, or joint problems. The tumor may also mechanically compress nerves or vessels. Osteochondromas growing inwardly may cause injury to internal organs. The authors present a preterm (34 weeks of corrected gestational age) neonate in whom osteochondroma, although histologically benign, caused death because of its size and location. Prenatal ultrasound imaging performed during the third trimester of pregnancy showed bilateral hydrothorax and hydroperitoneum as well as heterogeneous parenchymal area on the right side of the thorax. After birth, the neonate's condition was extremely severe. Although intensive and multidirectional treatment was applied, the condition of the infant continued to deteriorate and he died 26 h after birth. The autopsy confirmed presence of the tumor - osteochondroma - that caused total mediastinal shift with significant hypoplasia of both lungs and with signs of significant compression of the superior and inferior vena cava.