A hydropneumothorax is a term denoting the simultaneous presence of air and fluid in the pleural space. This clinical entity may be encountered in numerous conditions, including severe infections, trauma, and malignant diseases, with respiratory symptoms depending on the course and severity of hydropneumothorax, as well as accompanying respiratory changes. Plain X-rays are sufficient to make the diagnosis.
Although a hydropneumothorax is not frequently mentioned in the medical literature , its non-specific clinical appearance has been attributed to several conditions. Tumors, such as malignant pleural mesotheliomas (MPMs) and angiosarcomas, are documented as potential causes, whereas tuberculosis is designated as the most common infectious etiology of a hydropneumothorax, but hydatid lung disease caused by echinococcus granulosus is also reported as a possible cause    . On the other hand, invasive procedures of the lungs - thoracocentesis, placement of chest tubes and even a transbronchial biopsy all carry a risk for a post-procedural hydropneumothorax, suggesting their important role in the pathogenesis of this condition . The clinical presentation starts with an acute onset of respiratory insufficiency characterized by dyspnea, breathlessness and an overall decline in respiratory function, whereas additional signs of fever and constitutional symptoms (weight loss, malaise, anorexia) are often seen if tuberculosis is the underlying cause . Chest pain aggravated by deep breathing and a cough is reported in patients who suffer from hydatid disease, in whom cystic penetration into the pleural space causes hydropneumothorax . In a small number of cases, an urticarial reaction and even anaphylaxis can occur once immune cells interact with the echinococcal cysts .
Although a hydropneumothorax is principally diagnosed through imaging studies, physicians can include it in the differential diagnosis of respiratory symptoms only after a thorough patient history and a physical examination focused on lung auscultation. Tachypnea, signs of cyanosis and an "inconclusive" lung sound heard at the level of hydropneumothorax formation should prompt the physician to order a plain chest X-ray, a procedure that will undoubtedly reveal an air-fluid level lined almost perfectly at a horizontal level, mimicking pleural effusion . Furthermore, signs of lung collapse and pleural effusion may be shown on plain radiography and computed tomography (CT), which is also recommended during workup, especially if radiography is not conclusive . However, transthoracic sonography (TS) has shown to be an equally useful method in detecting pleural pathologies . In fact, its cost-effectiveness and the ability to perform the procedure bed-side, favor its use over plain radiography, especially when only supine X-rays can be carried out due to the overall condition of the patient .