Alveolar sarcoidosis is an atypical pulmonary manifestation of sarcoidosis.
This appearance may be apparent in approximately 4% of those with pulmonary sarcoidosis on plain film 1 and up to 15% on CT 2.
This appearance is thought to result from the aggregation of a vast number of interstitial granulomas rather than representing a true alveolar process. Some authors have therefore applied a more appropriate term, pseudoalveolar sarcoidosis.
There can be large areas of pulmonary opacification ranging in diameter from 1 to 4 cm. These can be rounded or elongated in shape, have irregular edges and blurred margins, with or without air bronchograms. They are typically found either along the bronchovascular bundles or in the lung periphery adjacent to the pleural surface (i.e., subpleural) 3.
When these opacities are accompanied by multiple surrounding nodules, representing granulomas as well, the entire conglomerate is often termed the galaxy sign.
Another pattern of alveolar sarcoidosis is an appearance termed "fairy ring", which refers to circumferentially organized opacities. In this situation, a reverse halo sign may be seen.
Treatment and prognosis
With prompt and appropriate treatment the parenchymal changes are usually reversible 6.
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- 2. Park HJ, Jung JI, Chung MH et-al. Typical and atypical manifestations of intrathoracic sarcoidosis. Korean J Radiol. 2009;10 (6): 623-31. doi:10.3348/kjr.2009.10.6.623 - Free text at pubmed - Pubmed citation
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- 4. Ors F, Gumus S, Aydogan M et-al. HRCT findings of pulmonary sarcoidosis; relation to pulmonary function tests. Multidiscip Respir Med. 2013;8 (1): 8. doi:10.1186/2049-6958-8-8 - Free text at pubmed - Pubmed citation
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- 6. Traill ZC, Maskell GF, Gleeson FV. High-resolution CT findings of pulmonary sarcoidosis. AJR Am J Roentgenol. 1997;168 (6): 1557-60. doi:10.2214/ajr.168.6.9168723 - Pubmed citation
- 7. Kuhlman JE, Fishman EK, Hamper UM et-al. The computed tomographic spectrum of thoracic sarcoidosis. Radiographics. 1989;9 (3): 449-66. doi:10.1148/radiographics.9.3.2727355 - Pubmed citation
- 8. Ibn Sellam A, Zahraoui R, Soualhi M et-al. [The pseudoalveolar form of sarcoïdosis: a diagnostic pitfall]. Rev Mal Respir. 2007;23 (4 Pt 1): 367-72. Pubmed citation
- 9. Elicker BM, Webb WR. Fundamentals of High-Resolution Lung Ct. Lippincott Williams & Wilkins. (2013) ISBN:1451184085. Read it at Google Books - Find it at Amazon
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