cystic lung diseases

Lymphangioleiomyomatosis cystic lung disease mimics.

(A) Centrilobular emphysema—note the lack of a true cyst wall and the presence of the centrilobular artery (arrowhead) within the cystic region. (B) Pulmonary Langerhans cell histiocytosis—note unusually shaped cysts (arrowheads) and numerous nodules. (C) Birt-Hogg-Dubé syndrome—note lower lobe predominance of cysts. Spontaneous pneumothorax (asterisks) is present bilaterally. (D) Lymphocytic interstitial pneumonia—the cysts in this disorder may closely simulate lymphangioleiomyomatosis, particularly when no other infiltrative parenchymal findings coexist. (E) Lymphangioleiomyomatosis, presented for comparison. Note the relatively uniform, thin-walled appearance of the cysts with normal-appearing intervening lung parenchyma.1

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The radiographic and histologic findings presented are consistent with the diagnosis of sarcoidosis (choice D is correct) (Figure 4). With that said, the chest CT findings in this patient are not typical of sarcoidosis. The CT shows bilateral perilymphatic cystic and cavitary lesions in a central/mid-to-upper lung zone distribution, as well as extensive mediastinal and hilar adenopathy. Cysts and cavities, when present, are mostly related to fibrotic changes with advanced sarcoidosis. Rarely, cavities can be the presenting feature of sarcoidosis. Primary cavitary sarcoidosis (PCS) is extremely rare, and is reported in less than 1% of cases. In a large series of 1,060 cases of sarcoidosis, the prevalence of cavitary lung lesions was 2.2%. Seventeen of the 23 cases with cavitary sarcoidosis were found to be chronic fibrocystic sarcoidosis seen in stage IV disease. PCS was diagnosed in only six cases, suggesting a prevalence of PCS of only 0.56%. Micronodules are the most common parenchymal manifestation of sarcoidosis and are found in a perilymphatic distribution, along the bronchovascular bundles, interlobular septa, major fissures, and subpleural regions. Cavitation occasionally occurs within these nodules. Although the precise mechanism underlying the formation of cavities remains unclear, the histopathology of PCS is characterized by noncaseating granulomas with minimal fibrosis within the cavity walls (Figure 5). Pulmonary function testing (PFT) in sarcoidosis characteristically reveals a restrictive pattern with a reduction in the diffusing capacity to carbon monoxide (Dlco). Endobronchial involvement may lead to impairment of airflow and obstructive respiratory physiology.

Footnotes

  1. Murray and Nadel Ch 97 Lymphangioleiomyomatosis ↩

  2. Algorithmic approach to multiple intraparenchymal cysts. Abbreviations: HRCT, high-resolution CT; BHD, Birt-Hogg-Dubé; H/O, history of; LAM, lymphangioleiomyomatosis; TS, tuberous sclerosis [complex (TSC)]; PTX, pneumothorax; PFT = pulmonary function test; HMB-45, Human Melanoma Black. Figure courtesy of Raoof S, Bondalapati P, Vydyula R, et al. Cystic lung diseases: algorithmic approach. Chest. 2016;150(4):945-965. ↩