Unilateral agenesis of the lung: a rare entity.

BACKGROUND: Agenesis of the lung, a rare congenital anomaly, arises or develops when there is disruption of evolution of the primitive lung bud, leading to complete absence of the lung, bronchi, and the main pulmonary artery. With right-sided agenesis, a variety of cardiac and other congenital malformations are more commonly seen, leading to a poor prognosis. CASE REPORT: A young female, aged 15 years, presented with complaints of sore throat and cough. Her x-ray of the chest showed a homogeneous opacity in the middle and lower zones on the right side with marked shift of the mediastinum to the right side. Upon investigation, she was diagnosed with agenesis of the right lung with scoliosis, without any other congenital anomaly. CONCLUSIONS: Especially in adults, it requires a high level of good clinical judgement to identify and diagnose this congenital aberration, as they are often wrongly diagnosed as more common diseases associated with unilateral opaque hemithorax on x-ray. Hence, when confronted with an opaque hemithorax with shift of the mediastinum to the affected side in a young person, "agenesis of the lung" should be an important differential diagnosis while investigating the case.

Complicated hydatid cyst and "air bubble" sign: a stepping-stone to correct diagnosis.

BACKGROUND: Hydatid cyst, or Echinococcosis, is an important helminthic zoonotic disease in humans that commonly affects the liver and lungs. Uncomplicated hydatid cysts, seen as round opaque lesions on chest radiography, are easily diagnosed, whereas complicated cysts (infected and or perforated) may change the radiographic appearance of the hydatid cyst, causing an incorrect diagnosis and delayed treatment. Although in radiology many signs have been described, the "air bubble" sign, seen in the mediastinal window of CECT as a single or multiple small rounded radiolucent areas with sharp margins within the periphery of a solid mass lesion, is being recognized as a sign with high sensitivity and specificity in the diagnosis of complicated hydatid cysts. CASE REPORT: A 32-year-old female on anti-tubercular treatment for the past 3 months without any improvement was admitted to our hospital. CECT of the chest revealed a mass-like lesion with the "air bubble" sign. After 15 days the patient had a vigorous bout of coughing, leading to expectoration of pieces of whitish yellowish gelatinous membrane for the next 3 days. The ELISA result for Echinococcus was highly positive. On the basis of the "air bubble" sign, positive serology, and expectorated pieces of the membrane, the patient was diagnosed as having a complicated hydatid cyst. CONCLUSIONS: Due to the varied presentations of complicated hydatid cyst, the knowledge and awareness of various signs in radiology associated with the hydatid cyst, in particular the "air bubble" sign, is imperative in making a prompt and accurate diagnosis of a complicated hydatid cyst.