대한흉부영상의학회 Korean Society of Thoracic Radiology

Discussion

Diagnosis With Brief Discussion

Courtesy

S

Imaging Findings

PA chest radiograph shows mild thickening of paratracheal stripe, bilateral hilar prominency, and reticular opacities in both mid-lung zones.
Thin-section lung window CT scans show diffuse thickening of bilateral bronchovascular bundles,
fissural thickening, and centrilobular micronodules with some subpleural micronodules.
Contrast-enhanced CT scans show bilateral mediastinal, subcarinal, and hilar lymph node enlargement.

Discussion

Sarcoidosis is a systemic granulomatous disease of unknown etiology that affects young adults and
typically manifests with bilateral hilar adenopathy, pulmonary infiltrates, uveitis, and erythema nodosum.
Microscopically there are widespread epitheloid noncaseating granulomas in more than one organ.

Several authors have described that the major CT finding in patients with pulmonary sarcoidosis is thickened bronchovascular bundles
(i.e., irregularly enlarged vessels, thickened bronchial wall, and small nodules along vessels).

Approximately 60-70 % of patients with sarcoidosis have a characteristic radiologic appearance consisting of
enlarged hilar and paratracheal lymph nodes with our without concomitant parenchymal changes.
In 25-30 % of cases, however, the radiologic findings are nonspecific or atypical, and in 5-10 % of patients the radiograph is normal.

The variable and nonspecific radiographic findings are surprising given the characteristic pathologic appearance and distribution of sarcoidosis.
Sarcoid granulomas, the hallmark of the disease, are distributed along the lymphatics in the bronchovascular sheath and,
to a lesser extent in the interlobar septa and pleura.
This perilymphatic distribution is difficult to appreciate on the radiograph because of the superimposition of the parenchymal shadows,
but often it can be on CT.

Hamper et al assessed the typical and atypical CT manifestations in 36 patients.
Subpleural nodules were seen in some patients, but no mention was made of peribronchovascular distribution or thickening of the interlobular septa.
In this present case, the parenchymal finding on CT consisted of nodules along the bronchovascular bundles.
This reflects the distribution of sarcoid granulomas.
Established sarcoid fibrosis, when present, was also more marked along the bronchovascular bundles.

The distribution of sarcoid granulomas along the lymphatics is similar to that seen with pulmonary lymphangitic carcinomatosis.
Both conditions cause a beaded appearance of the bronchovascular bundles and of the interlobular septa.
The nodules in sarcoidosis often have irregular margins; those in lymphangitic carcinomatosis are rather smooth.
Irregular linear opacities and evidence of fibrosis are also more suggestive sarcoidosis.
In some patients, however, the pattern of parenchymal involvement of sarcoidosis may be identical to that of lymphatic spread of tumor.

Reference

1. Melissa L. Rasado de Christenson. Imaging insights: pulmonary sarcoidosis. Radiology 1993;187:883
2. Scadding JG, Mitchell DN, eds. Sarcoidosis. Lodon: Chapman and Hall Medical, 1985:101-180
3. Hamper UM, Fishman EK, Khouri NF. Typical and atypical CT manifestation of pulmonary sarcoidosis. J Comput Assist Tomogr 1986;10:928-936
4. Muller NL, Mawson JB. Sarcoidosis: Correlation of CT with clinical, functional, and radiologic findings. Radiology 1989;171:613-618
5. Lee KS, Kim TS, J Han, et al. Diffuse micronodular lung diseases: thin-section CT and pathologic findings. J Comput Assist Tomogr 1999;23:99-106

Keywords

Lung, Idiopathic interstitial pneumonia, Sarcoidosis,