Chromosome 22q11 Deletion Complicated by Dissecting Pulmonary Arterial Aneurysm and Jejunal Atresia in an Infant Open Access

It is now well documented that the majority of cases of DiGeorge syndrome and velocardiofacial syndrome result from a chromosome 22q11 deletion. Patients with this chromosomal anomaly may have variable manifestations in several organs, including cardiac defect of various types, abnormal facies, thymic hypoplasia or aplasia associated with T-cell deficiency, cleft palate, and hypoparathyroidism/hypocalcemia.1–4 Recently, Ryan et al4 reported that 8% (44/558) of the patients in their large series of chromosome 22q11 deletion cases died, usually within 6 months, and all except 1 of the deaths were due to congenital heart disease. Although noncardiac vascular anomalies are common in patients with chromosome 22q11 deletion,2 we found no report referring to abnormalities in the intrapulmonary branches of the pulmonary artery.

The patient described here, a 46-day-old Japanese male infant with chromosome 22q11 deletion, had multiple dissecting pulmonary arterial aneurysms (PAAs) distributed in both lungs, in addition to cardiac defects, abnormal facies, thymic hypoplasia, and hypocalcemia. Pulmonary arterial aneurysm, a rare pathologic condition, usually occurs in the trunk or the main pulmonary artery of adults with various disorders.5–9 In this report, we describe this extremely rare pulmonary vascular lesion and discuss its possible association with chromosome 22q11 deletion. In addition, we briefly comment on the other notable finding, multiple jejunal atresia with apple-peel deformity, which also to our knowledge has not been reported in association with chromosome 22q11 deletion.

The male proband was the first child of healthy, nonconsanguineous Japanese parents. The mother and father were 30 years old at the time of his birth. At 34 weeks' gestation, the mother was referred to our hospital because of possible intestinal atresia in the fetus. The patient was born at 35 weeks and 1 day of gestation and weighed 1906 g. Laboratory tests revealed no significant abnormalities except hypocalcemia (1.55–1.88 mmol/L). Further examination revealed a small ventricular septal defect and closing patent ductus arteriosus, which were considered to be non–life-threatening. Surgery for intestinal atresia was performed successfully at day 1. The small bowel showed 5 atretic lesions of the jejunum and absence of the dorsal mesentery. The distal small bowel was considerably reduced in length and was twisted around a marginal artery (apple-peel deformity10). Soon after the operation, the patient developed progressive anemia, thrombocytopenia, and intermittent pulmonary hemorrhage, followed by right cardiac failure, hepatic dysfunction, and renal failure. The patient died of multiple organ failure at day 46. Chromosome analysis was obtained from peripheral blood lymphocyte culture with phytohemagglutinin stimulation. Routine chromosome analysis showed a normal male karyotype, but fluorescence in situ hybridization analysis of peripheral blood lymphocytes revealed microdeletion at chromosome 22q11 [46,XY.ish del(22)(q11.2q11.2)(cosG1+,ADUBP−,TUPLE1−,N25−,cos77−,D0832−,cos40−,cHKAD26−,cosD1+)], confirming a common large deletion of chromosome 22q11.11 (cosG1, ADUBP, TUPLE, etc, are locus-specific DNA probes that are sequential with cosG1 centromeric and cosD1 telomeric; a plus or minus sign after the locus symbol indicates whether it is present or absent. All loci tested between cosG1 and cosD1 are deleted.)

The patient showed external minor abnormalities, including hypertelorism, small mouth, and anteverted nares. The thymus was hypoplastic (0.4 g, expected value 10 g). The heart revealed a small (2 × 2-mm) ventricular septal defect and closing patent ductus arteriosus. The postoperative intestine was patent and appeared to be functioning. The lung showed focal bronchopneumonia, multiple thrombi, and focal hemorrhagic infarcts. Hypertensive vascular changes remained within a mild degree (Heath-Edward grade I/II). Of note was a peculiar lesion in the intrapulmonary branches of the pulmonary arteries. The cut surface of the lung demonstrated dissections of pulmonary artery branches, creating pseudolumens often filled with blood (Figure 1). The pseudolumens were mainly localized within the media (Figure 2). Elastic fiber layers of the media were severely disrupted and disarranged. Some of the lesions were fresh and filled with red blood cells. The others were in chronic phase, showing organizing change, scattered calcification, and collections of hemosiderin-laden histiocytes. There was no significant accumulation of mucoid substance in the media. The lesions, observed in multiple areas of both lungs, were limited to large and medium-sized intrapulmonary branches of the pulmonary artery. The main pulmonary arteries, ductus arteriosus, aorta including the major branches, and veins showed no remarkable change. No overt tear sites were detected grossly; however, microscopic examination demonstrated occasional extension of the lesion to the intima, suggesting that the lesion and the true lumen communicated.

Fewer than 10% of cases with chromosome 22q11 deletion are considered fatal, mostly as a result of congenital heart disease.4 Unfortunately, only a few detailed autopsy records have been described in such cases. In spite of relatively mild congenital heart disease (small ventricular septal defect and closing patent ductus arteriosus), our patient developed obstinate pulmonary hemorrhage and, subsequently, multiple organ failure. Autopsy unexpectedly disclosed multiple dissecting PAAs, which were considered to be the cause of pulmonary hemorrhage, disturbance of pulmonary blood flow, thromboembolism, and constant consumption of platelets.

Pulmonary arterial aneurysm, a rare pathologic condition usually occurring in adults, has various etiologies, including infection, Marfan syndrome, atherosclerosis, vasculitis, and chronic pulmonary hypertension with or without congenital heart disease.5–9 Pulmonary artery anomalies have often been described in patients with chromosome 22q11 deletion, but most have involved stenosis or atresia of the main pulmonary arteries.12 Dissecting PAA is very rare, usually occurring in the pulmonary trunk or the main pulmonary artery. There has been one case report of chromosome 22q11 deletion with PAA in a neonate, but the PAA involved only the main trunk and showed no dissection.9 Dissecting intrapulmonary PAA is extremely rare,5–7 and we found no reports of this lesion during infancy in the English literature. Autopsy in the present case showed no pathologic condition other than pulmonary hypertension, which can cause PAA secondarily. But the pulmonary hypertension noted in this case was too mild to cause PAA in such a short clinical course. The presumed congenital nature of PAA strongly favored primary structural abnormalities in the pulmonary artery.

Goldberg et al2 stated that the most common anomalies in velocardiofacial syndrome, a major component of chromosome 22q11 deletion, are the behavioral manifestations and noncardiac vascular anomalies, most of which are not life-threatening. To our knowledge, no cases of chromosome 22q11 deletion with PAA have been reported to date. Because of the diagnostic difficulty from the clinical point of view, PAA might easily be overlooked unless autopsy is performed. Accumulation of pathologic examinations in the future will clarify whether this rare lesion is a mere coincidental occurrence or a significant complication in patients with chromosome 22q11 deletion.

The other notable finding was multiple jejunal atresia with apple-peel deformity. Recent studies demonstrated intestinal tract abnormalities, especially anal anomalies, in patients with chromosome 22q11 deletion.13 However, intestinal atresia has not been described in association with chromosome 22q11 deletion. Since intestinal atresia is not an extremely rare anomaly, mere coincidence with chromosome 22q11 deletion in this case is possible. Another explanation is that the multiple jejunal atresia with apple-peel deformity was related to some structural abnormalities in the mesenteric artery, possibly associated with chromosome 22q11 deletion.