BAL was introduced for therapy in 1922 & diagnostic
use in 1974. BAL specimens may be obtained and sent to the lab
for cytology, cell count with differential, cytopathology examination,
and microbiology cultures. BAL for diagnosis of a focal process
will come from that segment; assessment of diffuse lung disease
usually comes from the RML or the left lung lingula, each accessible
with patient supine; usually one or a series of 204-60
ml. instillations with fluid recovery & subsequent pooling3.
These anterior sites allow "down-hill" return of fluid and a better yield. At least one authority3 writes that BAL can distinguish
between the 3 entities (EAA, IPF, & sarcoidosis) said to cause
90% of cases of interstitial lung disease (ILD). Here are some
notes that have come to our attention:
- gross exam of fluid: milky fluid may reflect alveolar
proteinosis1; others describe it as opaque brownish or sandy colored fluid which sediments out into layers if left to sit8.
- total cell count: the normal adult non-smoker cell
count is 4-23 cells per microliter1; smokers
have higher counts1; or average a slightly
lower count3.
- cell sample differential percentages implications:
- polys: are
0.1-4.4% of recovered cells1 (<3%8)& increased
in smokers1; up to 5 fold increase & up
to 5% of cells in smokers5.
In scleroderma "activity" workups, one is more likely to consider therapy when greater than 3 polys per microliter7.
- ***neutrophilia increases
the likelihood of an underlying fibrosing process (IPF, fibrosing
alveolitis of rheumatoid disease, asbestosis, or fibrotic sarcoid)6.
- some hypersensitivity pneumonitis.
- mild increase in EAA3.
- some IPF have an increase3,5;
70-90% are 5% or more6.
- mild increase in asbestosis.
- increased in idiopathic fibrosis and collagen vascular diseases.
- lymphocytes: are
10% (<15%8)of recovered cells2& mildly increased
in smokers1.
CD4/CD8 ratios might help in some DDXs (see8).
- ***a BAL lymphocytosis is
more suggestive of nonspecific interstitial pneumonia (NSIP), granulomatous
disease, or a drug-induced lung disease6.
- lymphocytosis of T helper cells1 more likely
reflects sarcoid; the helper:suppressor ratio (CD4/CD8) is frequently
high3.
- easily found (more than rare) lymphocytic rosettes around alveolar
macrophages tend to reflect sarcoidosis2.
- a lone lymphocytosis suggests sarcoidosis, granulomatous infection,
hypersensitivity pneumonitis, BOOP, nonspecific interstitial pneumonia
(NSIP), or LIP6.
- mild increase in asbestosis.
- some IPFs have an increase3; 10-20% have co-increase
with other cells6. But IPF seldom has just a lone
increase in lymphs and such indicates another disease6.
- increased in silicosis.
- present in berylliosis.
- hypersensitivity pneumonitis (extrensic allergic alveolitis [EAA])
has increased suppressor T lymphocytes1 and a low
CD4:CD8 ratio3.
- eosinophiles: usually
less than 1-2%8 of cells
- more likely reflects allergic or active asthmatic
- stable asthmatics have up to 5%.
- increased in idiopathic pulmonary fibrosis1 (IPF)
and collagen vascular diseases; some IPFs have an
increase3; 40-60% of IPFs have greater
than 5%6.
- greater than 40% eos seen with eosinophilic pneumonia
or acute tropical pulmonary eosinophilia.
- some hypersensitivity pneumonitis.
- plasma cells:
- presence highly suggestive of EAA (extrensic allergic alveolitis)3.
- macrophage clues: usually
90% of rcovered cells in normal nonsmokers
- macrophages tend to be (80%2)
84-99% of recovered cells1.
- macs engulf RBCs within 48 hours of bleed8.
- iron positivity reflects alveolar hemorrhage1.
- easily found (more than rare) lymphocytic rosettes
around alveolar macrophages tend to reflect sarcoidosis2.
- foamy macs nonspecific but common if patient on amiodarone8.
- a few Langerhans cells (dendritic macrophages)
in smokers & some interstitial lung diseases & more
numerous in eosinophilc granuloma1...and
histiocytosis X...Langerhans cell histiocytoses (IHC for S100)8.
- smears ID & cultures for microbiology:
- DFA stain for whatever LML can DFA; Gram for bacteria; AFB stain; silver stain fungi & P. car. (PCP).
- can send for PCR for various organisms such as M. tb.
- can culture for bacteria, fungi, and AFB.
- careful: healthy persons can shed cultureable
CMV or HSV in absence of pneumonia, but finding of cytopathic
change or inclusions is accepted as evidence of actual
infection1.
- upper lobe BAL specimens are the most likely to show
organisms of P. carinii.
- cancer cells: primary malignancies & even lymphangitic spread, can be seen1, 8.
- polarized light exam: for talcosis, silicosis, & asbestosis
bodies.
- wet prep exam: could note ciliary action of repiratory epithelium as appearing normal or dysfunctional.
- steroid responders: citing a 1981 study of "cryptogenic
fibrosing alveolitis", the corticosteroid responders tended
to have higher lymphocyte counts whereas the nonresponders had
higher polys and eos5.
References:
- Goldstein RA, et. al., Official ATS Statement, Clinical Role
of BAL in Adults With Pulmonary Disease, Am. Rev. Resp. Dis.,
142:481-486, 1990.
- M Drent, MA van Nierop, FA Gerritsen, EF Wouters and PG Mulder
Department of Pulmonology, University Hospital Maastricht, The Netherlands.
A computer program using BALF-analysis results as a diagnostic tool in
interstitial lung diseases, Am. J. Respir. Crit. Care Med., Vol 153, No.
2, 02 1996, 736-741.
- Drent, Marjolein, et. al., Interpretation of BALF Cytology,
CD ROM information webfile (http://www.pul.unimaas.nl/theses/bal_cd.pdf.).
- Leslie KO & Wick MR, Practical Pulmonary Pathology:
a Diagnostic Approach, 813 pages, 2005.
- Dail DH & Hammar SP, Pulmonary Pathology, 2nd Ed., 1640
pages, 1994.
- ATS International Concensus Statement, Idiopathic Pulmonary
Fibrosis: Diagnosis and Treatment, Am. J. Respir. Crit. Care
Med., Vol 161, No. 2, 02 2000, 646-664.
- per our pulmonologists.
- American Thoracic society website, BAL, on-line atlas of critical care procedures 12/08.
(posted 14 July
2005; latest addition 1 January 2008) |
