Figures
- Figure 1
a) HRCT image of the lungs in sporadic LAM, demonstrating bilateral rounded cysts, and b) automated CT software image.
- Figure 2
Typical HRCT appearances of the lungs in BHD.
- Figure 3
Lung cysts and mid and upper lobe infiltrates in biopsy-proven hypersensitivity pneumonitis, with accompanying fibrotic change. The sensitising agent was the pet parrot.
- Figure 4
Thick-walled cysts in respiratory papillomatosis.
Tables
- Table 1
Causes of cystic lung disease
Associated with genetic mutations Lymphangioleiomyomatosis (tuberous sclerosis-associated and sporadic) Birt–Hogg–Dubé syndrome and other folliculin deficiencies Proteus syndrome, neurofibromatosis, Ehlers–Danlos syndrome, Marfan syndrome Neoplastic Pulmonary Langerhans cell histiocytosis, other histiocytoses (e.g. Erdheim–Chester disease) Metastatic sarcoma, cavitating adenocarcinomas Benign metastasising leiomyoma Associated with lymphoproliferative disorders Lymphocytic interstitial pneumonia Follicular bronchiolitis Amyloidosis Light chain deposition disease IgG4-related disease Associated with infections Pneumocystis jirovecii Staphylococcal pneumonia Respiratory papillomatosis Parasitic and fungal diseases (e.g. coccidiocomycosis, paragonimiasis) Occupational and environmental Hypersensitivity pneumonitis (e.g. farmer's lung, bird fanciers' lung) Hard metal lung disease (tungsten carbide sensitisation) Chronic beryllium disease (beryllium sensitisation) Respiratory bronchiolitis associated interstitial lung disease (smoking/? vaping) Hut lung (biomass fuels) Associated with interstitial lung disease Hypersensitivity pneumonitis Honeycombing in idiopathic pulmonary fibrosis Honeycombing in asbestosis and other pneumoconioses Conditions that may mimic cystic lung disease Emphysema α1-antitrypsin deficiency Bronchiectasis Sarcoidosis Cavities in rheumatoid arthritis, Crohn's disease, coal workers' pneumoconiosis (Caplan's syndrome) - Table 2
Characteristics of different diffuse cystic lung diseases
LAM PLCH BHD Lymphocytic interstitial pneumonia Amyloidosis Light chain deposition disease Infection Pathogenesis Proliferation of abnormal smooth-like muscle cells (LAM cells)
Sporadic or autosomal dominant (TSC-LAM)
Infiltration and destruction by CD1a+ Langerhans-like cells
Autosomal dominant (FLCN gene)
Diffuse reactive pulmonary lymphoid hyperplasia
Idiopathic or associated with an underlying immunological condition
Misfolding protein and its extracellular deposition as fibrils
Accumulation of monoclonal light chain secreted by a clone of plasma cells
PJP: fungal infection
RRP: HPV-6 and -11
Clinical Hx Occurs almost exclusively in women
Young smokers
Both sexes
Relative with BHD or FHx of pneumothoraces, skin lesions and renal cancer
Hx of autoimmune conditions or immunological conditions, e.g. Sjögren syndrome, HIV
Presents in the sixth decade of life
Hx of Sjögren syndrome, lymphoproliferative disease or lymphoma
Lymphoproliferative disorders
PJP: immunocompromised host
RRP: upper airway symptoms (hoarse voice, wheeze, stridor)
Distribution of cysts Diffuse
No lobar predominance
Upper and middle lobes
Sparing costophrenic angles
Basal predominance
Subpleural
Perivascular
Diffuse (often subpleural and perivascular)
Diffuse
Diffuse
PJP: upper lobe predominance
RRP: predominately lower lobes
Shape Round
Irregular
Round, elliptiform, lentiform
Round
Round
Round
Variable
Other findings on HRCT Chylous pleural effusions
Symmetric reticulo-micronodular infiltration ±cavities
Nil
Ground-glass infiltrates, poorly defined centrilobular nodules, interlobular septal thickening
Multiple nodules abutting cyst walls
Multiple nodules
PJP: bilateral ground glass (apical predominance, peripheral sparing), consolidation, linear reticular opacities, nodules, parenchymal cavities
RRP: solid nodules, tracheal wall irregularities, bronchiectasis
Extrapulmonary manifestations Renal angiomyolipomas
Chylous effusions (pleural or ascites)
Lymphangioleiomyomas
TSC: skin lesions, seizures, hamartomatous lesions in various organs
Adult PLCH is generally isolated
Rarely: bones (lytic lesions), pituitary (diabetes insipidus), skin rash
Skin fibrofolliculomas
Renal tumours
Autoimmune diseases and associated symptoms including sicca symptoms and Raynaud's
Renal, cardiac, gastrointestinal, neurological and skin manifestations
Renal failure
Lymphoproliferative disorders
PJP: immunosuppression, constitutional features
RRP: upper airway involvement
Supporting investigations VEGF-D >800 pg·mL−1
Tbbx or VATS biopsy
BRAF mutation testing
Tbbx or VATS biopsy
Genetic testing for FLCN mutations
Imaging for renal tumours
Skin biopsy
Autoimmune panel
HIV testing
VATS biopsy
Presence of monoclonal protein
VATS biopsy
Investigation for lymphoproliferative disorder
Renal biopsy
VATS biopsy
HIV status, CD4+ cell count
PCR of induced sputum, BAL fluid or nasopharyngeal aspirates
Treatment mTOR inhibition: everolimus, sirolimus
Smoking cessation
Nil
Corticosteroids and immunosuppression
Treatment of underlying disease
Treatment of underlying disease
PJP: trimethoprim-sulfamethoxazole
RRP: cidofovir
PLCH: pulmonary Langerhans cell histiocytosis; BHD: Birt–Hogg–Dubé syndrome; Hx: history; FLCN: folliculin; PJP: Pneumocystis jirovecii pneumonia; RRP: recurrent respiratory papillomatosis; HPV: human papilloma virus; FHx: family history; VEGF: vascular endothelial growth factor; Tbbx: transbronchial biopsy; VATS: video-assisted thoracoscopic surgery; BAL: bronchoalveolar lavage; mTOR: mammalian target of rapamycin.
Centrilobular emphysema Centrilobular lucencies that lack distinct walls Predominately upper lobes after tobacco smoking Cystic bronchiectasis Associated with bronchial dilation Connected to tubular airways Cavity Gas-filled space Wall thickness >4 mm Develops in an area of pulmonary consolidation, mass or nodule Bulla An airspace (size >1 cm) with a round focal lucency, bounded by a thin wall (<1 mm) Bleb Small sized (<1 cm), gas-containing space within the visceral pleura or in the subpleural area Pneumatocele A thin-walled, gas-filled space in the lung, caused by infection, trauma, aspiration of hydrocarbon fluid Honeycombing Subpleural, multiple cystic cluster, typically 3–10 mm in diameter with well-defined walls
