Category | Key examples |
Disorders more prevalent in infancy |
Developmental lung disorders | - Alveolar capillary dysplasia, with and without misalignment of the pulmonary veins
- Acinar dysplasia and congenital alveolar dysplasia
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Alveolar growth abnormalities | - Pulmonary hypoplasia – eg, due to oligohydramnios, congenital diaphragmatic hernia, giant omphalocele, thoracic mass lesion
- Chronic neonatal lung disease (bronchopulmonary dysplasia) – eg, due to prematurity
- Associated with congenital heart disease
- Structural changes due to chromosomal abnormalities – eg, trisomy 21
- May be a manifestation of certain single-gene disorders, including NKX2-1 and FLNA
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Other forms of diffuse lung disease presenting in infancy | |
Genetic disorders of surfactant dysfunction and related abnormalities | - Mutations in the SFTPB, SFTPC, ABCA3, NKX2-1, and RAB5B genes are associated with altered surfactant production¶
- Mutations in the CSF2RA, CSF2RB, SLC7A7, MARS1, GATA2, STAT5B, and OAS1 genes impact the catabolism of surfactant via macrophage dysfunction; clinical manifestations may include pulmonary alveolar proteinosisΔ
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Disorders not specific to infancy |
Disorders of the normal host (immunocompetent) | - Bronchiolitis obliterans – A clinical syndrome and histologic phenotype that may be caused by infectious (eg, adenovirus) or noninfectious processes (eg, toxic inhalation, chronic hypersensitivity pneumonitis, or connective tissue disease)
- Infectious/postinfectious processes – May cause chronic airway changes, bronchiolitis obliterans, or organizing pneumonia
- Related to environmental agents (toxic inhalation or hypersensitivity pneumonitis)
- Aspiration syndromes
- Idiopathic pulmonary hemosiderosis
- Other disorders (eosinophilic pneumonia, AIP, NSIP)
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Disorders of the immunocompromised host | - Opportunistic infections
- Related to therapeutic intervention – eg, chemotherapy and/or radiation injury; drug reaction
- Related to transplantation or rejection syndromes (including bronchiolitis obliterans)
- Primary immunodeficiencies or immune regulatory disorders – eg, pathogenic variants in STAT3, GATA2, COPA, CTLA4, or LRBA; STING-associated vasculitis with onset in infancy
- Common histologic patterns include LIP and follicular bronchiolitis
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Disorders related to systemic disease processes | - Rheumatic disease/autoimmune – eg, juvenile systemic sclerosis (scleroderma); juvenile polymyositis/dermatomyositis; juvenile idiopathic arthritis; mixed connective tissue disease; systemic lupus erythematosus; Sjögren disease, anti-GBM antibody (Goodpasture), eosinophilic granulomatosis with polyangiitis, ANCA-associated vasculitides
- Metabolic or storage diseases – eg, Niemann-Pick disease, mucopolysaccharidosis, acid sphingomyelinase deficiency, glycogen storage diseases
- Nonspecific pulmonary manifestations – NSIP, pulmonary hemorrhage syndromes, organizing pneumonia, nonspecific airway changes◊
- Sarcoidosis
- Dyskeratosis congenita (bone marrow hypoplasia, often with skin, nail, and mucosal changes)
- Langerhans cell histiocytosis
- Malignant infiltrates
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Vascular disorders masquerading as ILD | - Pulmonary hypertension
- Congestive vasculopathy and veno-occlusive disease
- Lymphatic disorders – eg, lymphangiectasia, lymphangiomatosis
- Pulmonary edema
- Thromboembolic disease
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Unclassified | - Captures cases of diffuse lung disease that cannot be classified for any reason; common reasons include end-stage disease, nondiagnostic biopsies, or inadequate biopsy material
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