Pulmonary choristoma in a neonate

After a gestation period of 36 weeks, a 2,792 g male infant was born via cesarean delivery to a 32-year-old mother, gravida 6, para 3, spontaneous abortion 2. The mother had ingested Preludin (phenmetrazine hydrochloride) during early pregnancy. She had ingested no other medications, alcohol, or tobacco, except for aspirin and vitamins. First trimester bleeding resolved without medical treatment. At birth, the baby had Apgar scores of 8 at 1 mm and 8 at 5 mm but immediately developed respiratory distress and required resuscitation with mask, bagging, and oxygen. He was then transferred to our medical center where a workup including cultures of urine, blood, and spinal fluid was negative. He was given parenteral antibiotics for presumed pneumonia. Physical examination revealed occasional nasal flaring, a few basal rales, but no wheezes. The initial film, shortly after birth, showed haziness throughout the lungs, hyperexpansion, and mediastinal shift to the left (fig. 1 A). Three days later, after the rest of the lungs had partially cleared, a faintly opaque density could be identified occupying the right upper lobe. The inferior margin was indistinct. The mediastinal shift to the left remained, with secondary compression of the left lung. Minute rounded air shadows were identified within the right upper lobe mass (fig. 1 B). By 1 0 days, the rest of the lungs had cleared completely, and it was now apparent that there was an opaque mass occupying the enlarged right upper lobe and causing a mediastinal shift. Within the mass, there were tiny, irregularly shaped air bubbles, 1 -2 mm in diameter (fig. 1 C). A radionuclide scan showed a right-sided, nonsegmental, matching filling defect consistent with the abnormal area of plain film findings. On the 1 0th day, a right upper lobectomy was performed. The resected specimen consisted of a 36 g, 6 x 5.5 x 2.3 cm lobe of lung with smooth pink-tan pleural surfaces. Most of the lobe was occupied by a 4.4-cm-diam spherical mass of homogeneous pinktan finely spongy tissue. No capsule was identified, but the mass appeared well demarcated from the contiguous pulmonary tissue. A bronchial stump was present, but direct communication into the mass was not demonstrated. Histologic sections showed an orderly pattern of interconnecting fascicles of well differentiated striated skeletal muscle fibers enclosing irregular complex cystic spaces linked by well differentiated pseudostratified columnar epithelium. Alveolar structure, present in sequestrations and emphysematous conditions, was completely lacking within the monotonous cystic pattern. No significant mucous gland proliferation was present as would be expected for adenomatoid malformations. Scattered through this arrangement were portions of well formed bronchi containing smooth muscle bundles and cartilage plates in their walls. No proliferation of smooth muscle was present as in the fibroleiomyoma hamartomatous disorders. Serial sections showed no obvious connection between these normal bronchial divisions and the cystic spaces. Vascular fibrous septa divided the tumor mass into ovoid lobules. The boundary with the adjacent normal lung tissue was sharp in some areas and indistinct in others. No capsule was present (figs. 2A and 2B). The infant did well postoperatively and was discharged on the 23d day of life.