Radiographic Findings

Representative radiographs and CTs are shown below.

A chest radiograph obtained on presentation shows a diffuse, fine-nodular pattern in the lungs. This can best be appreciated by comparing with a chest film taken 3 years before (below), which demonstrates normal pulmonary parenchyma and prominent pulmonary vessels. Rapid development of diffuse, 3-5 mm pulmonary nodules (not present on a film taken 2 months before) is worrisome for miliary tuberculosis.

What other diseases can cause diffuse tiny nodules (less than 5 mm)? Answer

Also note the increased prominence of the central hilar structures in the current film.

The elevation of the right hemidiaphragm, noted on films taken over a 9-year period, represents an eventration of the diaphragm.

CTs--Image 1: Lung Window

CT on presentation shows the central hilar prominence to be a combination of adenopathy and thickening of the central bronchovascular interstitium. The mass-like bronchovascular thickening is best seen on Image 1 extending from the hilum into the anterior segment of the LUL and Image 2 extending into the middle lobe. Also note evidence for architectural distortion (usually related to fibrosis) with a medial positioning of the anterior segment LUL bronchus.

Lung window Images 1 and 2 also demonstrate the distribution of the parenchymal nodules. Note multiple, tiny nodules at the anterior, subpleural regions, bilaterally; one (RUL, Image 1) at a thickened, peripheral, interlobular septum at 10 o'clock; a few along the major fissures; and a few at the bronchovascular interstitium of the anterior segment RUL pulmonary artery.

Image 2: Lung Window

There are also multiple nodules in a centrilobular distribution, seen best in the anterior portions of the RLL and in the RML. A few are also seen at the ends of vessels.

This distribution of nodules fits the description of a random or miliary pattern--nodules randomly distributed in relation to small vessels, pleura, and interlobular septa [1], except for one difference: these nodules are not uniformly distributed. The nodules in this case predominate in some portions of the lung and spare other portions, particularly the LLL. Case 32 has an excellent example of true random nodules for comparison.

Image 3: Mediastinal Window

 

 

Mediastinal windows (Images 3 and 4) demonstrate bilateral hilar adenopathy and adenopathy in the right paratracheal and precarinal spaces and aorticopulmonary window.

Adenopathy is also evident in the azygoesophageal recess in Image 3.

Image 4: Mediastinal Window

Abnormal small lymph nodes are also seen in the prevascular space anterior to the aortic arch in image 4.

Reference

1.Webb W, Müller N, Naidich D: High-resolution CT of the Lung, 2nd ed., Philadelphia, Lippincott-Raven Publishers, 1996, p 63.

Clinical summary Clinical summary continued

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Answer: Miliary fungal disease (histoplasmosis, coccidioidomycosis, blastomycosis, cryptococcosis), varicella pneumonia, hematogenous metastatic malignancy (especially tumors of the thyroid, kidney, breast, and pancreas, and choriocarcinoma and melanoma), bronchioloalveolar carcinoma, lymphangitic tumor and lymphoma, silicosis and other pneumoconioses, sarcoidosis, and eosinophilic granuloma [1]. Very rare causes include hemosiderosis, alveolar microlithiasis, amyloidosis, hypersensitivity pneumonia, nocardia, and bronchiolitis.

Reference

1. Slone R. Differential diagnosis for the chest. In Slone R, Gutierrez F, Fisher A eds: Thoracic Imaging: A Practical Approach. New York, McGraw-Hill, 1999, p 31.

Clinical summary Clinical summary continued

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