Congenital right lung hypoplasia associated with dextrocardia

To the Editor, We read with interest the report of Almansori and Ouf [1], describing the case of an absence of the right lung associated with dextro-position of the heart in a 49-year-old female patient, who presented with pneumonia. We would like to make some comments on this regard. Absence of the lung is an extremely rare congenital anomaly resulting from a failure of development of the primitive lung bud [1–3]. Pulmonary agenesis is classified into three categories: Type 1 (Agenesis) – complete absence of lung and bronchus and no vascular supply to the involved side [2,3]. Type 2 (Aplasia) – rudimentary bronchus with complete absence of pulmonary parenchyma [2,3]. Type 3 (Hypoplasia) – presence of variable amounts of bronchial tree, pulmonary parenchyma and supporting vasculature [2,3]. Typical radiographical findings seen on chest X-ray in cases of absence of right lung are: homogeneous opacity (or hyperopacity) of the right hemithorax, compensatory hyperinflation of the controlateral left side, elevated right hemidiaphragm, tracheal, mediastinal and cardiac shift to the defective left side [2,3]. As far as one can observe, the chest X-ray provided by the authors [1] does not, in our opinion, show typical findings of a complete absence of the right lung, Type 1 (agenesis), but rather specific findings, which are consisting with Type 3, i.e. hypoplasia of the right lung [1]. The provided chest X-ray shows in our opinion, a still aerated pulmonary parenchyma, modest elevated of the right hemidiaphragm [1]. Further the chest X-ray shows a right sided shift of the heart, left aortic arch, and left gastric air bubble, findings which are consistent with dextrocardia with situs solitus [1]. Neither hyperopacity of the right side, nor shift of the trachea to the right side are, in our judgment, clearly observed [1]. Further, the statement of the authors [1], that “dextro-position of the heart is a rare condition, often misdiagnosed as dextrocardia”, is still a matter of a debate, since dextro-position of the heart is considered by other investigators as a subtype of dextrocardia [4]. Three types of dextrocardia, or the “right lying heart”, were described [4,5]. The most common and familiar is the “mirror image of normal” or “mirror-image dextrocardia”, in which the anterior-posterior relationship of the various parts of the heart are normal but their right to-left orientation is reversed [4,5]. It occurs in one or two in 20,000 persons [5]. It is associated with some degree of abdominal situs inversus, in which the stomach and spleen lie in the right, while the liver lies in the left [4,5]. In 2013, we have encountered a case of 22-year-old female patient with dextrocardia (Fig. 1) and situs inversus, who was admitted because of 2 weeks history of frequent episodes of orthostatic collapse. The second type, is dextrocardia with situs solitus, D-loop ventricles, and normally related great arteries [4,5]. It has been also termed as “dextroversion” because the heart appears to be rotated into the right hemithorax relative to its normal position [4,5]. The third type of dextrocardia, is dextroposition, as the case described by Almansori and Ouf, in which an otherwise normal heart is displaced or shifted into the right hemithorax by other extracardiac causes such as agenesis or fibrosis of the right lung and right pneumonectomy [1,4,5]. Figure 1 Chest radiography shows the cardiac apex facing the right, right-sided aortic arch, a right hemi-diaphragm lower than the left and a right gastric air bubble, findings which are consistent with dextrocardia and situs inversus totalis.