Today’s radiographs belong to a 54-year-old man with vague chest complaints.
What do you see?
Check the images below, leave your thoughts in the comments section, and come back on Friday for the answer.
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Findings: PA radiograph shows a poorly defined paramediastinal opacity (A, arrow) that is projected over the trachea in the lateral view (B, arrow).
Coronal and sagittal enhanced CT demonstrate a spiculated lung nodule (C and D, arrows), highly suspicious of malignant disease.
Final diagnosis: carcinoma of the lung
In Diploma cases 123–126, I reviewed the various presentation forms of lung carcinoma as an aid to identify them. In the next two Diplomas, I intend to discuss how to avoid missing them and incurring a potentially harmful delay in the diagnosis.
Overlooking lung cancer has two main causes:
Faulty visualization, in which the lesion is hidden by chest structures
Failure of recognition: the neoplasm is seen, but is confused with benign disease
In this presentation I will review the causes of faulty visualization, which may be due to the lesion being hidden by chest organs or obscured by overlying lung disease.
Overlooking a lesion is our most common mistake, accounting for around 50% of errors. A carcinoma in any part of the lung can be missed (Fig. 1), but it occurs more commonly in what is called the blind areas of the chest. In the PA radiograph these include the apical region, the hila and mediastinal shadows, and the areas behind both hemidiaphragms (Fig. 2).
The lung apices are difficult to evaluate because of the superimposed first ribs and clavicles (Fig. 3). Radiologists miss 25% to 50% of nodules in the apical regions. The missed nodules have a mean size of 1.6 cm (Fig. 4).
The hilar regions are imprecise areas where small tumors in the vicinity may go unrecognized if the hila are not examined carefully (Fig. 5). Any increased opacity of the hilum should always be investigated to exclude malignancy (Fig. 6).
The mediastinal shadow can hide large-size tumors in the PA view (Fig. 7). That is why a lateral view should always be taken when studying the chest.
The hemidiaphragms hide a significant portion of the lower lobes. A carcinoma in this location may be barely visible in the PA view and better seen in the lateral projection (Figs. 8 and 9).
Coronal and sagittal enhanced CT demonstrate a large necrotic mass in the RLL (C and D, arrows). Needle biopsy confirmed the diagnosis of carcinoma.
Faulty visualization can also be due to the tumor being obscured by overlying lung disease, either acute (Fig. 10) or chronic.
Chronic diffuse lung disease can also hide a malignancy. This is important to consider because patients with interstitial lung disease are known to have a higher incidence of tumors (Figs. 11 and 12).
Follow Dr. Pepe’s advice:
1. Lung tumors may be hidden in the “blind” areas of the PA view.
2. These include the apices, hilar and mediastinal shadows, and both hemidiaphragms.
3. Lung disease, either acute or chronic, can also hide lung tumors.