Study Smarter
Nipple shadows can often mimic pulmonary nodules. Clues to nipples being the source of the apparent nodules on the lateral radiograph, bilaterally and “lesions” whose inferior and lateral borders appear sharper than their superior and medial margins. Confirmation can be obtained by repeating the study with nipple markers or obtaining a different projection.
Components of the PA mediastianl shadow (A) include SVC (1), ascending aorta (2), RA (3), IVC (4), aortic arch (5), pulmonary trunk (6), LA appendage (7), and LV (8).
Mediastinal compartments on the lateral film (B) include: superior (S), anterior (A), middle (M) and posterior (P) compartments.
This is a normal lateral film of a female patient. Note the spine (sp), anterior costophrenic angle (acpa), gastric air bubble (gab), trachea (tr), left mainstem bronchus (lbr), right mainstem bronchus (rbr), aortic arch (ao), anterior/retrosternal (acs) and posterior/retrocardiac (pcs) clear spaces, and breast shadow (m)
On a film taken in full inspiration, the right hemidiaphragm should project over the 6th anterior interspace or 10th rib posteriorly. Films taken without a full inspiration are described as having a “poor inspiratory result”. This may result from a poor inspiratory effort or any other condition that prevents full inspiration.
This patient’s chest x-ray is normal in full inspiration. In relative expiration, the cardiac silhouette appears enlarged and the pulmonary vasculature appears crowded and indistinct. This appearance is easily mistaken for pulmonary edema
Hypertrophic First Rib
Rib hypertrophy, often at the costochondral junction and particularly involving the first rib, commonly mimics a lung nodule on the PA projection. It has been called “the medical student’s tumor.” Clues that the “nodule” is in fact due to rib hypertrophy include its absence on the lateral view, bilaterality, and the presence of rib hypertrophy at other levels. If there is any doubt, a lordotic projection can be obtained.
This patient has a well circumscribed mass in the posterior mediastinum. The valve of the lateral view is well depicted in this case; on the frontal radiograph there is no way to localize the lesion. The differential diagnosis for a posterior mediastinal mass includes:
This mass proved to be a neurofibroma.
This patient has a large mass in the middle mediastinum. The differential diagnosis for such a mass includes:
This elderly patient complained of gastroesophageal reflux symptoms. This clinical history, plus the presence of an air-fluid level within the mass suggests a hiatus hernia.
PA and lateral chest radiographs of a hiatal hernia. Left: PA chest view demonstrates a retrocardiac lucency with well defined lateral margins. Right: Lateral radiograph shows a large hiatal hernia in the middle mediastinum. Hiatal hernia is the most common radiographic abnormality of the middle mediastinum.
Radiologists divide the mediastinum into 3 compartments. The most popular classification is Felson’s division of the thorax into the following 3 compartments:
This approach is very useful in classifying mediastinal masses (please refer to Diagnostic Medical Imaging Chapter or to examples of mediastinal masses to follow).
There is a large mass in this patient’s anterior mediastinum. The differential diagnosis for such a mass includes:
In this case, the mass is accompanied by significant hilar and paratracheal lymphadenopathy. The patient is young and complains of fevers and night sweats. He was diagnosed with Hodgkin’s Lymphoma.
