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Pulmonary agenesis and related anomalies
Pulmonary
Agenesis By Benjamin
and Related Felson,
Anomalies
M.D.
C
ONGENITAL ABSENCE or underdevelopment of a lobe is a surprisingly common lesion. I have never seen it in the left lung. Three forms, all usually asymptomatic, have been described: agenesis, in which there is complete absence of the lobe as well as its bronchus (Fig. 1); aphasia, in which there is no lung tissue but a rudimentary lobar bronchus (Fig. 2A); and hypoplasiu, in which bronchi and alveoli are present but the lobe is underdeveloped.‘~‘8~‘g~23 Roentgenologically, there is displacement of the mediastinal structures toward the affected side, moreso on inspiration.‘r The involved lung shows normal or diminished radiolucency along with diminution in volume. Often there is loss of the silhouette of the right side of the heart and ascending aorta at the site of the absent lobe (Fig. 2B). This is difficult to understand since compensatory overexpansion of the remaining lobes should bring them alongside the heart border. The explanation lies in the failure of the remaining aerated lobes and the parietal pleura encasing them to extend anteriorly all the way to the chest wall. Instead, extrapleural areolar tissue has taken the place of the missing lobe and occupies the anteromedial portion of the thoracic cavity alongside the right heart border, between the parietal pleura posteriorly and the thoracic cage anteriorly.8 This extrapleural tissue is better seen in the lateral view as an anterior opacity paralleling the sternum from diaphragm to clavicle (Figs. 2C and 10B). In this projection, it simulates LUL collapse except that there is no hilar connection (mediastinal wedge), and of course it is on the wrong side. Its sharp posterior border represents the parietal pleura covering the anterior margin of the remaining normal right lung. The diagnosis of agenesis or aplasia is readily established by bronchography.15 In agenesis, the bronchus to the missing lobe is simply not there. In aplasia, the blind bronchus often has a distinctive smooth round-bottomed termination, about the shape of September morn (Fig. 10). The only other condition I have seen resembling it is a bronchus severed by trauma (fractured) or by the surgeon (Fig. 3). The bronchial tree supplying the remaining overexpanded pulmonary tissue has spread out to accommodate itself to the increased intrathoracic space. Interestingly, the large bronchi have become rearranged to simulate the normal anatomy. In fact, when two lobes remain, the bronchial tree is said to mirror that of a normal left lung. 2-ssgBut to me they don’t, because they extend over a larger area than they were designed to and the bronchi are smaller in caliber than normal segmental bronchi (Fig. 4). Absence of an entire lung is more readily recognized because the thorax is completely opaque and there is striking displacement of the mediastinal Supported in part Benjamin Felson, College of Medicine, Seminars
by USPHS Grant GM 72458-02. M.D.: Professor and Director Cincinnati, Ohio 45229.
in Roentgenology,
Vol.
7, No. 1 (January),
of Radiology,
1972
University
of Cincinnati
17
18
BENJAMIN
FELSON
Fig. 1. Lobar agenesis. There is only one lobar bronchus on the right, probably supplying the RML. An anomalous vessel (arrow) is visible in the right medial lung base. The trachea and heart are deviated to the right but the right hemidiaphragm is in normal position. The right heart border showed partial obliteration on the plain film. The left main stem is unusually long and the anatomy of the left bronchial tree is probably also abnormal. structures, diaphragm, and normal lung into the affected hemithorax.7*‘0*‘3 Daves claims that, unlike acquired gross loss of pulmonary volume, in congenital absence the external diameter of the affected hemithorax is not significantly smaller than the normal side. 6 Either lung may be totally absentI (Figs. 3 and 5). The pulmonary and bronchial arteries are lacking.22 The Scimitar
Syndrome
Lobar agenesis or aplasia is frequently associated with other anomalies in the thorax and reported under such interesting titles as the scimitar syndrome, the hypogenetic lung syndrome, the epibronchial right pulmonary artery syn-
F.ig. 2. Aplasia. A. The rudimentary lobar bronchus (arrow) is the only vestige of the congenitally absent RUL and RML. B. PA teleroentgenogram, same patient. The right border of the
heart and ascending aorta are obliterated. The right leaf of the diaphragm is elevated, especially laterally. (Continued on following page.)
BENJAMIN
C. Lateral rows point border of separated wall by a extrapleural patient as
FELSON
view. The arto the anterior the right lung from the chest thick layer of tissue. Same Fig. 7.
drome,” and the mivvor image ftrng syndrome,5 all of which are the same entity. The term scimitar syndvome, which I have come to prefer, implies the presence of partial anomalous pulmonary venous return below the diaphragm.2,3s12 This anomalous vessel, also occurring almost exclusively on the right side, drains into the inferior vena cava, portal vein, or a hepatic vein. Rarely it enters the lower right atrium directly (Fig. 1OC). The left-to-right shunt is hardly ever of clinical magnitude. The roentgen shadow of the anomalous vein has been likened to a Turkish scimitar5~16~20*21 (Fig. 6), although it reminds me more of a woman’s leg. But then anything does. The third component of the syndrome is less constant: a systemic artery arising from the lower thoracic or upper abdominal aorta and supplying the right lower lung. It occasionally supplies an area of pulmonary sequestration. The right pulmonary artery, which is small to begin with because it supplies fewer lobes than normal, provides no branches to the pulmonary tissue supplied by the anomalous systemic artery. 22,134In fact, the right pulmonary artery may be completely absent and the entire blood s~ipply to the right lung be derived from the aorta (Fig. 7). Anomalies about the right hemidiaphragm are commonly associated with the scimitar syndrome. These include accessory diaphragm (Fig. 8), hepatic herniation (Fig. o), phrenic cyst, sequestration, and rarely, absent inferior vena
PULMONARY
AGENESIS
21
Fig. 3. Agenesis of entire left lung. The termination of the left main bronchus is rounded off. A similar appearance is seen in fractured bronchus. Note the herniated right lung (arrows).
Fig. 4. Bronchial rearrangement in congenital absence of RUL and RML. Some similarity to the bronchial pattern of a normal left lung is noted. However, the bronchi here are smaller in caliber.
22
BENJAMIN
FELSON
PULMONARY
AGENESIS
23
Fig. 6. Anomalous drainage of right pulmonary vein below the diaphragm (scimitar shadow). PA teleroentgenogram. The aberrant vessel receives branches from most or all of the right lung and enlarges as it passes inferiorly toward the cardiophrenic angle (arrow) where it enters the abdomen, usually via the esophageal hiatus. Drainage is usually to the portal vein or inferior cava. Not proved.
Fig. 7. Pulmonary aplasia with total absence of the right artery. Same patient as Fig. 2. A. AP dextroangiocardiogram. is rotated into the right thorax. There is absence of the right trunk.
pulmonary The-heart pu.lmonary
B. Levoangiocardiogram. The right lung is supplied from the descending thoracic aorta by a single large vessel (arrowheads). (Courtesv of Dr. Dan R. McFarland, Witford Hall ‘Air Force Hospital.)
m
PULMONARY
AGENESIS
25
Fig. 8. Accessory diaphragm. A. There is loss of the right heart border and a peculiar flattopped hump on the right hemidiaphragm (arrow) in this infant. The heart is deviated to the right. B. AP bronchogram shows a constricted bronchus (arrow) leading into a small section of lung contained between two layers of the right hemidiaphragm. (Courtesy of Dr. James W. Passino, University of Tennessee, Knoxville, Tenn.)
cava (Fig. IO). Accessory diaphragm is a partially duplicated diaphragm that is fused anteriorly but separated posteriorly. The cephalic component extends upward and backward to join the posterior thoracic wall. Part or all of the RLL and sometimes the RML is contained between its layers.8 Any of the components of the scimitar syndrome may be absent in a given case. Tomography, bronchography, or angiography can establish which features are present. However, they are seldom necessary since the plain films are generally adequate for diagnosis and there is no need for a detailed demonstration of the specific anomalies since the condition is usually asymptomatic and seldom requires surgical treatment.
26
BENJAMIN
FELSON
PULMONARY
AGENESIS
27
Fig. 9. Hepatic herniation associated with the scimitar syndrome. A. Frontal view. An anomalous vessel associated with a mass is seen in the right cardiophrenic angle. B. Lateral view shows the mass lying below and behind the heart. C. Levoangiocardiogram. A large anomalous pulmonary vein passes through the diaphragm. At operation the hernia, the anomalous vessel, and an anomalous artery from the descending aorta passed through the same diaphragmatic defect. (Courtesy Dr. C. Vazan and Dr. B. B. Markette, San Antonio, Texas.)
28
BENJAMIN
FELSON
PULMONARY
29
AGENESIS
Fig. 10. Scimitar syndrome with probable absence of the inferior cava. A. On the PA teleroentgenogram, the gastric bubble is seen under the right hemidiaphragm (arrowhead). The end-on azygos vein visualized alongside the upper trachea is enlarged. The right heart border is lost and an anomalous vessel is seen in the right cardiophrenic angle (arrow). B. Lateral view. The extrapleural tissue replacing the missing lobe is clearly seen. C. Levoangiocardiogram shows entry of an anomalous pulmonary vein into the right atrium. An inferior vena cavagiam was not performed. (Courtesy of Cal. James Harrell, Walter Reed Army Hospital.) REFERENCES I. Bayindir, S., Bikfalvi, A., and Sailer, F. X.: Zur Frage der Lungen-Hypoplasie. Fortsch. Roentgen&r. 107:423, 1967. 2. Bessolo, R. J., and Maddison, F. E.: Scimitar syndrome: report of a case with unusual variations. Amer. J. Roentgen. 103
:572,
1968.
3. Bourassa,
M.
G.:
The
scimitar
syn-
drome: report of two cases of anomalous venous return from a hypoplastic right lung to the inferior vena cava. Canad. Med. Ass. J. 88:115, 1963. 4. Bruwer, A. J.: Posteroanterior chest roentgenogram in two types Of anomalous pulmonary venous connection. J. Thoracic Surg. 32:119, 1956.
30 5. Dalith, F., and Neufeld, H.: Radiological diagnosis of anomalous pulmonary venous connection: a tomographic study. Radiology 74:1, 1960. 6. Daves, M. L., and Walsh, J. A.: Minihemithorax. Amer. J. Roentgen. 109 :528, 1976. 7. Davidson, S. W.: Some anomalies of the respiratory system. J. Fat. Radiol. 8 :l, 1956. 8. Davis, W. S., and Allen, R. I’.: Accessory diaphragm: duplication of the diaphragm. Radiol. Clin. N. Amer. 6 :2iT3, 1968. 9. Ferencz, C., and Currarino, G.: Personal communication. 10. Field, C. E.: Pulmonary agenesis and hypoplasia. Arch. Dis. Child. 21:61, 1946. 11. Findlay, C. W., Jr., and Maier, H. C.: Anomalies of the pulmonary vessels and their surgical significance: with a review of the literature. Surgery 29:604, 1951. 12. Frye, R. L., Marshall, H. W., Kincaid, 0. W., and Burchell, H. B.: Anomalous pulmonary venous drainage of the right lung into the inferior vena cava. Brit. Heart J. 24~696. 1962. 13. Garber, R. L.: Congenital aplasia of the lung. Amer. J. Roentgen. 53 :129, 1945. 14. Holinger, I’. H.: Clinical aspects of congenital anomalies of the larynx, trachea, bronchi and oesophagus. J. Laryng. Otol. 75:1, 1961. 15. Huizinga, E., and van Weering, I. F.: Bronchography in agenesia and hypoplasia of the lung. Ann. Otol. 73 :26, 1964. 16. McKusick, V. A., and Cooley, R. N.: Drainage of right pulmonary vein into in-
BENJAMIN
FELSON
ferior vena cava: report of case, with a radiologic analysis of the principal types of anomalous venous return from the lung. New Eng. J. Med. 252:291, 1955. 17. Richter, K., et al.: The anomaly of the epibronchial right pulmonary artery as guiding symptom of a pulmo-cardiovascular syndrome. Fortschr. Roentgenstr. 107:31, 1967. 18. Schneider, L. : Bronchopulmonary hypogenesis : clinical and roentgenologic features in the adult, with long follow up observations. Amer. J. Med. Sci. 214 :665, 1948. 19. Stankey, R. M., Roshe, J., and Sogocio, R. M.: Carcinoma of the lung and dysphagia. Dis. Chest 55 :13, 1969. 20. Steinberg, I. : Anomalous pulmonary venous drainage of right lung into inferior vena cava with malrotation of the heart: report of three cases. Ann. Intern. Med. 47~227, 1957. 21. Steinberg, I.: Roentgen diagnosis of anomalous pulmonary venous drainage of right lung into inferior vena cava: report of three new cases. Amer. J. Roentgen. 81:280, 1959. 22. Steinberg, I., and Stein, H. L.: Angiocardiography in diagnosis of agenesis of a lung. Amer. J. Roentgen. 96~991, 1966. 23. Taybi, H. : Congenital malformations of the larynx, trachea, bronchi and lungs. In Kaufmann, H. J. (Ed.): Progress in Pediatric Radiology, Vol. 1. Chicago, Year Book Medical Publishers, 1967. 24. Viamonte, M., Jr.: Intrathoracic extracardiac shunts. Sem. Roentgen. 2 :342, 1967.
Agenesis By Benjamin
and Related Felson,
Anomalies
M.D.
C
ONGENITAL ABSENCE or underdevelopment of a lobe is a surprisingly common lesion. I have never seen it in the left lung. Three forms, all usually asymptomatic, have been described: agenesis, in which there is complete absence of the lobe as well as its bronchus (Fig. 1); aphasia, in which there is no lung tissue but a rudimentary lobar bronchus (Fig. 2A); and hypoplasiu, in which bronchi and alveoli are present but the lobe is underdeveloped.‘~‘8~‘g~23 Roentgenologically, there is displacement of the mediastinal structures toward the affected side, moreso on inspiration.‘r The involved lung shows normal or diminished radiolucency along with diminution in volume. Often there is loss of the silhouette of the right side of the heart and ascending aorta at the site of the absent lobe (Fig. 2B). This is difficult to understand since compensatory overexpansion of the remaining lobes should bring them alongside the heart border. The explanation lies in the failure of the remaining aerated lobes and the parietal pleura encasing them to extend anteriorly all the way to the chest wall. Instead, extrapleural areolar tissue has taken the place of the missing lobe and occupies the anteromedial portion of the thoracic cavity alongside the right heart border, between the parietal pleura posteriorly and the thoracic cage anteriorly.8 This extrapleural tissue is better seen in the lateral view as an anterior opacity paralleling the sternum from diaphragm to clavicle (Figs. 2C and 10B). In this projection, it simulates LUL collapse except that there is no hilar connection (mediastinal wedge), and of course it is on the wrong side. Its sharp posterior border represents the parietal pleura covering the anterior margin of the remaining normal right lung. The diagnosis of agenesis or aplasia is readily established by bronchography.15 In agenesis, the bronchus to the missing lobe is simply not there. In aplasia, the blind bronchus often has a distinctive smooth round-bottomed termination, about the shape of September morn (Fig. 10). The only other condition I have seen resembling it is a bronchus severed by trauma (fractured) or by the surgeon (Fig. 3). The bronchial tree supplying the remaining overexpanded pulmonary tissue has spread out to accommodate itself to the increased intrathoracic space. Interestingly, the large bronchi have become rearranged to simulate the normal anatomy. In fact, when two lobes remain, the bronchial tree is said to mirror that of a normal left lung. 2-ssgBut to me they don’t, because they extend over a larger area than they were designed to and the bronchi are smaller in caliber than normal segmental bronchi (Fig. 4). Absence of an entire lung is more readily recognized because the thorax is completely opaque and there is striking displacement of the mediastinal Supported in part Benjamin Felson, College of Medicine, Seminars
by USPHS Grant GM 72458-02. M.D.: Professor and Director Cincinnati, Ohio 45229.
in Roentgenology,
Vol.
7, No. 1 (January),
of Radiology,
1972
University
of Cincinnati
17
18
BENJAMIN
FELSON
Fig. 1. Lobar agenesis. There is only one lobar bronchus on the right, probably supplying the RML. An anomalous vessel (arrow) is visible in the right medial lung base. The trachea and heart are deviated to the right but the right hemidiaphragm is in normal position. The right heart border showed partial obliteration on the plain film. The left main stem is unusually long and the anatomy of the left bronchial tree is probably also abnormal. structures, diaphragm, and normal lung into the affected hemithorax.7*‘0*‘3 Daves claims that, unlike acquired gross loss of pulmonary volume, in congenital absence the external diameter of the affected hemithorax is not significantly smaller than the normal side. 6 Either lung may be totally absentI (Figs. 3 and 5). The pulmonary and bronchial arteries are lacking.22 The Scimitar
Syndrome
Lobar agenesis or aplasia is frequently associated with other anomalies in the thorax and reported under such interesting titles as the scimitar syndrome, the hypogenetic lung syndrome, the epibronchial right pulmonary artery syn-
F.ig. 2. Aplasia. A. The rudimentary lobar bronchus (arrow) is the only vestige of the congenitally absent RUL and RML. B. PA teleroentgenogram, same patient. The right border of the
heart and ascending aorta are obliterated. The right leaf of the diaphragm is elevated, especially laterally. (Continued on following page.)
BENJAMIN
C. Lateral rows point border of separated wall by a extrapleural patient as
FELSON
view. The arto the anterior the right lung from the chest thick layer of tissue. Same Fig. 7.
drome,” and the mivvor image ftrng syndrome,5 all of which are the same entity. The term scimitar syndvome, which I have come to prefer, implies the presence of partial anomalous pulmonary venous return below the diaphragm.2,3s12 This anomalous vessel, also occurring almost exclusively on the right side, drains into the inferior vena cava, portal vein, or a hepatic vein. Rarely it enters the lower right atrium directly (Fig. 1OC). The left-to-right shunt is hardly ever of clinical magnitude. The roentgen shadow of the anomalous vein has been likened to a Turkish scimitar5~16~20*21 (Fig. 6), although it reminds me more of a woman’s leg. But then anything does. The third component of the syndrome is less constant: a systemic artery arising from the lower thoracic or upper abdominal aorta and supplying the right lower lung. It occasionally supplies an area of pulmonary sequestration. The right pulmonary artery, which is small to begin with because it supplies fewer lobes than normal, provides no branches to the pulmonary tissue supplied by the anomalous systemic artery. 22,134In fact, the right pulmonary artery may be completely absent and the entire blood s~ipply to the right lung be derived from the aorta (Fig. 7). Anomalies about the right hemidiaphragm are commonly associated with the scimitar syndrome. These include accessory diaphragm (Fig. 8), hepatic herniation (Fig. o), phrenic cyst, sequestration, and rarely, absent inferior vena
PULMONARY
AGENESIS
21
Fig. 3. Agenesis of entire left lung. The termination of the left main bronchus is rounded off. A similar appearance is seen in fractured bronchus. Note the herniated right lung (arrows).
Fig. 4. Bronchial rearrangement in congenital absence of RUL and RML. Some similarity to the bronchial pattern of a normal left lung is noted. However, the bronchi here are smaller in caliber.
22
BENJAMIN
FELSON
PULMONARY
AGENESIS
23
Fig. 6. Anomalous drainage of right pulmonary vein below the diaphragm (scimitar shadow). PA teleroentgenogram. The aberrant vessel receives branches from most or all of the right lung and enlarges as it passes inferiorly toward the cardiophrenic angle (arrow) where it enters the abdomen, usually via the esophageal hiatus. Drainage is usually to the portal vein or inferior cava. Not proved.
Fig. 7. Pulmonary aplasia with total absence of the right artery. Same patient as Fig. 2. A. AP dextroangiocardiogram. is rotated into the right thorax. There is absence of the right trunk.
pulmonary The-heart pu.lmonary
B. Levoangiocardiogram. The right lung is supplied from the descending thoracic aorta by a single large vessel (arrowheads). (Courtesv of Dr. Dan R. McFarland, Witford Hall ‘Air Force Hospital.)
m
PULMONARY
AGENESIS
25
Fig. 8. Accessory diaphragm. A. There is loss of the right heart border and a peculiar flattopped hump on the right hemidiaphragm (arrow) in this infant. The heart is deviated to the right. B. AP bronchogram shows a constricted bronchus (arrow) leading into a small section of lung contained between two layers of the right hemidiaphragm. (Courtesy of Dr. James W. Passino, University of Tennessee, Knoxville, Tenn.)
cava (Fig. IO). Accessory diaphragm is a partially duplicated diaphragm that is fused anteriorly but separated posteriorly. The cephalic component extends upward and backward to join the posterior thoracic wall. Part or all of the RLL and sometimes the RML is contained between its layers.8 Any of the components of the scimitar syndrome may be absent in a given case. Tomography, bronchography, or angiography can establish which features are present. However, they are seldom necessary since the plain films are generally adequate for diagnosis and there is no need for a detailed demonstration of the specific anomalies since the condition is usually asymptomatic and seldom requires surgical treatment.
26
BENJAMIN
FELSON
PULMONARY
AGENESIS
27
Fig. 9. Hepatic herniation associated with the scimitar syndrome. A. Frontal view. An anomalous vessel associated with a mass is seen in the right cardiophrenic angle. B. Lateral view shows the mass lying below and behind the heart. C. Levoangiocardiogram. A large anomalous pulmonary vein passes through the diaphragm. At operation the hernia, the anomalous vessel, and an anomalous artery from the descending aorta passed through the same diaphragmatic defect. (Courtesy Dr. C. Vazan and Dr. B. B. Markette, San Antonio, Texas.)
28
BENJAMIN
FELSON
PULMONARY
29
AGENESIS
Fig. 10. Scimitar syndrome with probable absence of the inferior cava. A. On the PA teleroentgenogram, the gastric bubble is seen under the right hemidiaphragm (arrowhead). The end-on azygos vein visualized alongside the upper trachea is enlarged. The right heart border is lost and an anomalous vessel is seen in the right cardiophrenic angle (arrow). B. Lateral view. The extrapleural tissue replacing the missing lobe is clearly seen. C. Levoangiocardiogram shows entry of an anomalous pulmonary vein into the right atrium. An inferior vena cavagiam was not performed. (Courtesy of Cal. James Harrell, Walter Reed Army Hospital.) REFERENCES I. Bayindir, S., Bikfalvi, A., and Sailer, F. X.: Zur Frage der Lungen-Hypoplasie. Fortsch. Roentgen&r. 107:423, 1967. 2. Bessolo, R. J., and Maddison, F. E.: Scimitar syndrome: report of a case with unusual variations. Amer. J. Roentgen. 103
:572,
1968.
3. Bourassa,
M.
G.:
The
scimitar
syn-
drome: report of two cases of anomalous venous return from a hypoplastic right lung to the inferior vena cava. Canad. Med. Ass. J. 88:115, 1963. 4. Bruwer, A. J.: Posteroanterior chest roentgenogram in two types Of anomalous pulmonary venous connection. J. Thoracic Surg. 32:119, 1956.
30 5. Dalith, F., and Neufeld, H.: Radiological diagnosis of anomalous pulmonary venous connection: a tomographic study. Radiology 74:1, 1960. 6. Daves, M. L., and Walsh, J. A.: Minihemithorax. Amer. J. Roentgen. 109 :528, 1976. 7. Davidson, S. W.: Some anomalies of the respiratory system. J. Fat. Radiol. 8 :l, 1956. 8. Davis, W. S., and Allen, R. I’.: Accessory diaphragm: duplication of the diaphragm. Radiol. Clin. N. Amer. 6 :2iT3, 1968. 9. Ferencz, C., and Currarino, G.: Personal communication. 10. Field, C. E.: Pulmonary agenesis and hypoplasia. Arch. Dis. Child. 21:61, 1946. 11. Findlay, C. W., Jr., and Maier, H. C.: Anomalies of the pulmonary vessels and their surgical significance: with a review of the literature. Surgery 29:604, 1951. 12. Frye, R. L., Marshall, H. W., Kincaid, 0. W., and Burchell, H. B.: Anomalous pulmonary venous drainage of the right lung into the inferior vena cava. Brit. Heart J. 24~696. 1962. 13. Garber, R. L.: Congenital aplasia of the lung. Amer. J. Roentgen. 53 :129, 1945. 14. Holinger, I’. H.: Clinical aspects of congenital anomalies of the larynx, trachea, bronchi and oesophagus. J. Laryng. Otol. 75:1, 1961. 15. Huizinga, E., and van Weering, I. F.: Bronchography in agenesia and hypoplasia of the lung. Ann. Otol. 73 :26, 1964. 16. McKusick, V. A., and Cooley, R. N.: Drainage of right pulmonary vein into in-
BENJAMIN
FELSON
ferior vena cava: report of case, with a radiologic analysis of the principal types of anomalous venous return from the lung. New Eng. J. Med. 252:291, 1955. 17. Richter, K., et al.: The anomaly of the epibronchial right pulmonary artery as guiding symptom of a pulmo-cardiovascular syndrome. Fortschr. Roentgenstr. 107:31, 1967. 18. Schneider, L. : Bronchopulmonary hypogenesis : clinical and roentgenologic features in the adult, with long follow up observations. Amer. J. Med. Sci. 214 :665, 1948. 19. Stankey, R. M., Roshe, J., and Sogocio, R. M.: Carcinoma of the lung and dysphagia. Dis. Chest 55 :13, 1969. 20. Steinberg, I. : Anomalous pulmonary venous drainage of right lung into inferior vena cava with malrotation of the heart: report of three cases. Ann. Intern. Med. 47~227, 1957. 21. Steinberg, I.: Roentgen diagnosis of anomalous pulmonary venous drainage of right lung into inferior vena cava: report of three new cases. Amer. J. Roentgen. 81:280, 1959. 22. Steinberg, I., and Stein, H. L.: Angiocardiography in diagnosis of agenesis of a lung. Amer. J. Roentgen. 96~991, 1966. 23. Taybi, H. : Congenital malformations of the larynx, trachea, bronchi and lungs. In Kaufmann, H. J. (Ed.): Progress in Pediatric Radiology, Vol. 1. Chicago, Year Book Medical Publishers, 1967. 24. Viamonte, M., Jr.: Intrathoracic extracardiac shunts. Sem. Roentgen. 2 :342, 1967.