Table 2.
Radiologic and Pathologic Characteristics of Cysts Seen in Selected Diffuse Cystic Lung Diseases
| LAM | PLCH | BHD | LIP/FB | Amyloid/LCDD | |
|---|---|---|---|---|---|
| Distribution | Diffuse, random | Upper & middle lung zones; sparing costophrenic angles | Basilar/peripheral/subpleural and near vessels | Diffuse, random, often near vessels | Diffuse, random |
| Size | 2 mm to 2 cm | Variable, 2 mm to >2 cm | 75% <1 cm | Average size 3 mm to 1 cm | 4 to 45 mm, majority larger than 1 cm |
| Shape | Round, uniform | Bizarre, irregular | Elliptical, lentiform | Round, variable | Round, variable |
| Pathological examination diagnostic | Yes | Yes | No | Yes | Yes |
| Pathologic findings | Infiltration by HMB-45–positive LAM cells with smooth muscle phenotype | S100- and CD1a-positive Langerhans cells with intracellular Birbeck granules by electron microscopy; stellate fibrotic scars in late stages | Intraparenchymal and subpleural cysts abutting interlobular septae and lacking abnormal cell proliferations or significant fibroinflammatory component | LIP: diffuse interstitial polyclonal lymphocytic infiltrate | Amyloid: amorphous protein deposits with fibrillar ultrastructure and apple-green birefringence by Congo red stain viewed under polarized light |
| FB: peribronchiolar polyclonal follicular lymphoid hyperplasia with germinal centers | LCDD: typically monotypic kappa light chain deposition with finely granular ultrastructure lacking apple-green birefringence by Congo red stain and polarized light | ||||
| Other associated findings on HRCT | Pleural effusions | Micro and macro nodules with or without cavitation, thick-walled cysts, cavities and reticulation | Cysts frequently abut pleura and proximal vessels | Ground-glass attenuation, poorly defined centrilobular nodules, interlobular septal thickening, cysts may contain internal structure | Multiple nodules of varying attenuation and random distribution; nodules abut cyst walls |
Definition of abbreviations: BHD = Birt-Hogg-Dubé syndrome; FB = follicular bronchiolitis; HMB-45 = human melanoma black-45; HRCT = high-resolution computed tomography; LAM = lymphangioleiomyomatosis; LCDD = light-chain deposition disease; LIP = lymphoid interstitial pneumonia; PLCH = pulmonary Langerhans cell histiocytosis.