| An approach
to histopathological reporting of the
pulmonary parenchymal biopsies:
I) In the bronchioles:
- Peribronchial or
peribronchiolar inflammation:
Non-specific:
Reactive lymphoid follicles as in follicular
bronchiectasis or follicular
bronchiolitis
; Granulomatous .
- Obliterative changes in bronchioles with fibrous scarring, as in bronchiolitis obliterans:
- Organizing
granulation tissue in bronchiolar lumina, as in cryptogenic organizing pneumonia (also known as bronchiolitis obliterans organizing pneumonia or BOOP).
II) In the alveoli and interstitium:
- Architecture:
-Destruction
of alveolar walls without fibrosis in
emphysema
;
-Destruction of alveolar walls with interstitial and intra-alveolar fibrosis, alveolar collapse, and bronchiolization in advanced interstitial lung disease;
-Alveolar
walls:
- Interstitial inflammatory infiltration ;
- Focal acute inflammation with central necrosis and scattered giant cells in fungal pneumonias;
- Heavy lymphocytic infiltrate, as in lymphoid interstitial pneumonia
(LIP), extrinsic allergic alveolitis, monomorphic and
atypical lymphoid infiltrate, as in malignant lymphoma;
- Non-necrotizing well formed granulomas in
sarcoidosis ;
- Non-necrotizing poorly formed granulomas
in
extrinsic
allergic alveolitis;
- Necrotizing granulomas in mycobacterial
and
fungal infection ;
- Palisaded granulomas in Wegener’s granulomatosis
and
rheumatoid nodules
;
- Interstitial fibrosis;
-
Asbestos
bodies;
-
Amyloid;
- Smooth muscle cells in
lymphangioleiomyomatosis ;
- Lymphatic infiltration by tumour cells as in extra-pulmonary primary adenocarcinoma (lymphangitis carcinomatosa), lymphoma,
Kaposi's sarcoma
,
epithelioid
hemangioendothelioma ;
- Calcification- metastatic in the elastic of alveolar walls, dystrophic in areas of long-standing fibrosis;
- Calcified bodies (Schaumann bodies) in areas of hyaline fibrosis in
sarcoidosis;
- Hemosiderin deposition in areas of hemorrhage;
- Alveolar lining cells:
- Hyaline
membranes in diffuse acute alveolar damage;
- Proliferation of type II pneumocytes in the reparative phase of hyaline membrane disease;
- Multinucleate giant cells:
-giant cell interstitial pneumonia (hard metal
disease);
-giant cell pneumonia (
measles infection in children, occasionally
respiratory syncytial virus infection or
parainfluenza
B);
-viral inclusions, such as
cytomegalovirus or measles;
- cytoplasmic hyaline in type II pneumocytes, first identified in asbestosis but also seen in other conditions;
-atypical cells: seen with some cytotoxic drugs such as busulfan or
bleomycin;
-bronchiolisation
of distal air spaces in advanced diffuse pulmonary fibrosis;
-squamous metaplasia as a result of chronic inflammation ;
-tumour cells lining alveoli in bronchioloalveolar carcinoma, which
may be mucus secreting or non-mucus secreting.
- Alveolar lumina:
-Inflammatory
cells:
-polymorphs in bacterial pneumonias ;
-eosinophils in eosinophilic pneumonia ;
-histiocytes/macrophages - foamy in obstructive pneumonitis or
lipid pneumonia
, containing fine lipofuscin pigment in desquamated
interstitial pneumonia, ‘blue bodies’ associated with lysosomal accumulation in
such conditions as DIP ;
-multinucleate foreign body giant cells, often associated with
cholesterol crystal clefts, in obstructive pneumonitis or
pulmonary
alveolar proteinosis ;
-Granular eosinophilic debris, often with cholesterol crystals, in
pulmonary alveolar proteinosis,
- Granular and foamy lightly eosinophilic material in
pneumocystis pneumonia
;
- Hemorrhage or accumulation of haemosiderin-laden macrophages in
hemorrhagic diathesis, pulmonary capillaritis, idiopathic pulmonary
hemosiderosis, pulmonary venous hypertension;
- Intra-alveolar irregular laminated calcospherites in pulmonary
microlithiasia;
- Organizing exudates (Masson bodies
-Masson's Tumour) in organizing pneumonia;
III) In the blood vessels:
- Vasculitis:
-Eosinophil infiltration with granuloma
formation in Churg-Strauss syndrome;
-Extravascular granulomas and areas of necrosis
in Wegener’s granulomatosis;
-Granulomas in vessel walls in
sarcoidosis , necrotizing
sarcoidal granulomatosis, and reaction to talc
particles in drug addicts;
- Capillaritis with alveolar hemorrhage in
Wegener’s granulomatosis, microscopic polyarteritis and
hypersensitivity vasculitis;
- Infiltration of vessel walls by atypical
lymphoid cells in angiocentric lymphoma (lymphomatoid
granulomatosis);
- Pulmonary hypertension and thromboembolic disease:
- Muscular arteries - medial hypertrophy in
hypoxic pulmonary hypertension, pulmonary venous
hypertension and plexogenic pulmonary arteriopathy; subintimal
longitudinal muscle fibres in hypoxic pulmonary hypertension;
- Intimal thickening-eccentric in thromboembolic
pulmonary hypertension, associated with organizing
thrombus or other embolic material, concentric in plexogenic
pulmonary arteriopathy ; dilatation lesions, plexiform lesions
and fibrinoid necrosis in plexogenic pulmonary arteriopathy;
- Muscularization of arterioles in
hypoxic
pulmonary hypertension
;
- Veins:
- Obliteration by connective tissue in
pulmonary veno-occlusive disease;
- Thickening of the media with arteriolization in pulmonary venous hypertension;
- Replacement of the vein wall by a
network of capillaries with abnormal capillaries in alveolar walls in
pulmonary capillary hemangiomatosis.
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