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Key Points
Pulmonary agenesis is defined as complete absence or severe hypoplasia of one or both lungs.
Pulmonary agenesis may be found in isolation or in association with other malformations.
Bilateral agenesis of the lung is rare, and is incompatible with life; unilateral agenesis occurs more commonly, and may be compatible with normal life.
Sonographically, the mediastinum is shifted toward the affected side and the diaphragm on the ipsilateral side is elevated.
Detailed sonography and fetal magnetic resonance imaging (MRI) may distinguish unilateral pulmonary agenesis from other causes of mediastinal shift.
Unilateral or bilateral pulmonary agenesis is not thought to be associated with chromosomal abnormalities.
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Pulmonary agenesis is a rare developmental condition in which there is complete absence or severe hypoplasia of one or both lungs (Oyamada et al., 1953; Valle, 1955; Booth and Berry, 1967; Borja et al., 1970; Yaghmai, 1970; Costas et al., 1977; Boxer et al., 1978; McCormick and Kuhns, 1979; Shenoy et al., 1979; Mygind and Paulsen, 1980). Although quite rare, it was initially recognized by dePozzi in 1673 (Skandalakis and Gray, 1994). Munchmeyer was the first to diagnose unilateral agenesis of the lung clinically in 1885 (Ferguson and Neuhauser, 1944). There have since been more than 200 cases of unilateral agenesis of the lung reported. However, only 14 cases have been reported of bilateral agenesis of the lung (Allen and Affelbach, 1925; Tuynman and Gardner, 1952; Claireaux and Ferreira, 1957; Devi and More, 1966; Ostor et al., 1978; Faro et al., 1979; Diaz et al., 1989; Engellenner et al., 1989). In some cases, bilateral pulmonary agenesis was an isolated finding. In other cases, pulmonary agenesis was found in association with other anomalies in the gastrointestinal, genitourinary, and ocular systems (Tuynman and Gardner, 1952; Claireaux and Ferreira, 1957; Devi and More, 1966; Ostor et al., 1978).
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A number of theories have been advanced to explain the pathogenesis of lung aplasia. Lung aplasia has been observed in experimental animals fed a diet deficient in vitamin A (Warkany et al., 1948). Some authors have suggested that there may be a vascular cause of pulmonary agenesis, similar to that invoked for intestinal atresia (Louw, 1959). Other authors have suggested a genetic cause for the pulmonary agenesis. Booth and McKenzie and their colleagues linked unilateral pulmonary agenesis to ipsilateral facial and jaw abnormalities, an association noted more recently by several authors (McKenzie and Craig, 1955; Booth and Berry, 1967; Kenawi and Dickson, 1976; Maymon et al., 2001; Dorchy, 2004; Priolo et al., 2004). The gene involved may have a variable expressivity and penetrance. However, the actual cause of this type of pulmonary agenesis remains obscure.
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