RESUMEN
The authors reported a newborn female baby, 36 weeks gestational age, 2680 gms who developed respiratory distress at 2 hours after birth. Her chest roentgenograms showed a normal-sized heart, sparse lung markings and bilateral masses involving the posterior 6th to 8th ribs. Thoracotomy with partial removal of the left chest mass was performed when she was 12 hours age. Postoperatively, the baby developed progressive respiratory distress and expired at 29 hours-age. Autopsy revealed bilateral nodular masses arising from the inner side of the posterior aspect of the 6th to 8th ribs, measuring 6 x 5 x 4 cm (right) and 7 x 6 x 4 cm (left). The cut surfaces showed multicystic spaces containing blood. Histologically, many blood filled spaces with walls of fibroblasts, cartilage and bone tissue were noted. The diagnosis was mesenchymal hamartoma of the chest wall. Mesenchymal hamartoma of the chest wall usually arises from the posterior or lateral portions of the rib and usually involves many ribs. Multi focal lesions and bilaterality are rare. The clinical presentation can be asymptomatic, mild or severe respiratory distress. Surgical resection is the treatment of choice.