BAL/ tracheal wash Flashcards
What are the main indications for a tracheal wash/ BAL?
radiographic evidence of tracheobronchial or pulmonary disease resulting in a chronic cough or respiratory distress
How does mucus appear in wash samples?
Mucus stains as an eosinophilic background deposit
and can have a ‘fern-like’ appearance on direct smears
There are also Curshmann’s spirals - casts of
inspissated mucus from small bronchioles and can
be seen in any lower airway disease resulting in the
excessive production of mucus
What does lots of mucus suggest in airway samples?
Inflammation/ infection
What are goblet cells?
Goblet cells are mucus-producing bronchial cells
and contain large deeply basophilic mucin granules.
Increased numbers of goblet cells can be seen with
conditions resulting in chronic airway irritation and
overproduction of mucus (eg, chronic bronchitis and
feline bronchial asthma).
How do alveolar macrophages appear?
Alveolar macrophages may be the predominant cell
type found in TW/BAL samples from clinically normal
animals. The cytoplasm becomes vacuolated and may
contain phagocytosed debris when these cells become activated.
How do neutrophils appear?
Neutrophils normally constitute less than 5 per cent of the total nucleated cell population. Increased numbers are seen in cases of inflammation, infection or tissue necrosis (a variable number of macrophages may also be present). The presence of neutrophils showing degenerative changes is more indicative of bacterial infection or tissue necrosis
Outline eosinophils in wash samples
Eosinophils are normally present in very low numbers
(<5 per cent of the total nucleated cell population) in
dogs but the figure may be as high as 20 per cent in
some apparently healthy cats. An increased number of
eosinophils with variable numbers of neutrophils and
macrophages may be seen in the case of hypersensitivity reactions or parasitism (lymphocytes, plasma cells and mast cells may also be seen
Some eosinophils may appear morphologically atypical, with the nucleus being round or oval-shaped rather than segmented.
Outline lymphocytes in wash samples
Lymphocytes are present in low numbers in normal
dogs and cats (5 to 14 per cent). Increased numbers can be seen in patients with airway hypersensitivity and in response to antigenic stimulation (eg, viral diseases and chronic infections). Some lymphocytes may transform into plasma cells.
Outline mast cells in wash samples
Mast cells are rarely seen in TW/BAL samples
from healthy dogs and cats (less than 2 per cent of the
total nucleated cell population). The number may be
slightly increased in the case of some hypersensitivity
reactions.
What are the differentials for neutrophilic inflammation within a lung lobe?
Possible causes of a neutrophilic (purulent) inflammatory response include tracheobronchitis (eg, kennel cough), bronchopneumonia, inhaled bronchial/
pulmonary foreign bodies, aspiration pneumonia, a
pulmonary abscess or a large necrotic tumour
What type of inflammation do protozoal/ mycobacterial infections produce?
a granulomatous or pyogranulomatous inflammatory response. The latter is characterised by an
increased number of reactive alveolar macrophages
and a variable number of neutrophils. Lymphocytes,
plasma cells and eosinophils may be present in low
numbers. A granulomatous inflammatory response
is characterised by an increased number of reactive
epithelioid macrophages. Large multinucleated giant
cells may also be present.
How would cytology from a dog or cat with chronic bronchitis appear?
tends to be less specific. The inflammatory response may be relatively mild and there may be evidence of increased mucus production.
Likely a combination of of nucleated cells is more consistent with a chronic active or mixed inflammatory response, although in many cases macrophages may predominate
What are the ddx for eosinophilic inflammation?
feline bronchial asthma and pulmonary infiltrate
with eosinophils, which includes allergic bronchitis,
eosinophilic bronchopneumonia, pulmonary eosinophilic granuloma associated with Dirofilaria immitis infection, and neoplasia (eg, lymphomas, mast cell tumours). Parasitism (eg, involving Oslerus osleri,
Angiostrongylus vasorum, Crenosoma vulpis and
Aelurostrongylus abstrusus [cats])
What suggests intrapulmonary haemorrhage?
The presence of macrophages containing red blood
cells or haemoglobin breakdown products, such as
haemosiderin (haemosiderophages) or haematoidin
crystals
What are the ddx for intrapulmonary haemorrhage?
trauma, the presence of a pulmonary foreign body, infectious (bacterial, fungal, protozoal or parasitic) diseases, lung lobe torsion, feline bronchial asthma, congestive heart failure, pulmonary thromboembolism, coagulopathies (eg, dicoumarol toxicity) or primary/metastatic neoplasia.
