Table 2.
Description of HRCT Features of Rare Cystic Lung Diseases
| Condition | HRCT Features |
|---|---|
| HP | Centrilobular ground glass nodules with mosaic attenuation and airways involvement.6, 7 In < 10% of cases of HP, cysts are seen. These are usually few in number and random in distribution |
| MALToma | Diffuse multiple thin-walled cysts and small ill-defined nodules exhibiting a perilymphatic pattern in bilateral lung fields7 |
| Follicular bronchiolitis | Small centrilobular nodules with occasional peribronchial nodules and areas of ground-glass opacity. It is included in the same category of lymphoproliferative diseases as lymphoid interstitial pneumonia. In this disease, a major distinguishing feature from lymphoid interstitial pneumonia is that the findings are confined primarily to the peribronchiolar region and that ground-glass opacities are uncommon8, 9 |
| Lymphomatoid granulomatosis | Small thin-walled cysts, small lung nodules distributed in peribronchovascular (core) areas, coarse irregular opacities, and mediastinal nodal enlargement10 |
| Ankylosing spondylitis | Upper lobe predominant with apical fibrosis, associated interstitial lung disease and bronchiectasis. Seen in 10% of patients with ankylosing spondylitis11 |
| Neurofibromatosis | Numerous upper lobe predominant cysts seen bilaterally. Cysts more commonly seen in smokers12, 13 |
| Proteus syndrome | Rare syndrome characterized by vascular malformations and asymmetric postnatal overgrowth of connective tissues. Thin- and thick-walled cystic changes, as well as emphysematous enlargement of air spaces can be seen in approximately 10% of patients with Proteus syndrome14, 15 |
| Ehlers-Danlos Syndrome | Rare genetic disorder of connective tissues characterized by skin hyperextensibility, joint hypermobility, and tissue fragility. Multiple parenchymal cysts and cavities are rarely seen in patients with Ehlers-Danlos syndrome16 |
| Fire-eater’s lung | Chemical pneumonitis resulting from accidental aspiration of petroleum products. Cystic changes in lung parenchyma represent pneumatoceles, and they typically follow a benign course leading to resolution in a few weeks17, 18 |
| Hyper-IgE syndrome | Primary immunodeficiency condition characterized by multiple skin and sino-pulmonary infections, as well as an elevated IgE level. Lung cysts likely represent pneumatoceles secondary to staphylococcal infections19, 20 |
| CPAM | Presents as cystic or solid lung masses. The types of CPAM, based mainly on the size of the cysts, are as follows21, 36: Type 1 (70%): most common type, with large cysts (2-10 mm) Type 2 (20%): small uniform cysts, 0.5-2 cm in diameter, associated with air-filled multicystic masses or focal areas of consolidation Type 3 (10%): poor prognosis; lesions are visualized as multiple cysts < 2 mm in size that usually involve entire lobe of the lung Type 4: These are very large cysts, sometimes ≥10 cm in size usually affecting one lobe |
These are either rare or uncommon manifestations of cystic lung diseases that are not discussed in the current article. CPAM = congenital pulmonary airway malformation; HP = hypersensitivity pneumonitis; HRCT = high-resolution CT scan; MALToma = mucosa-associated lymphoid tissue lymphoma.