Diagnostic Cytology
Indications for Use:
1. Effusions—Abdominal and Thoracic
Our evaluation of such fluid samples would usually include cell
count and protein concentration to determine the category of fluid,
such as true transudate, modified transudate and exudate. This is
important to narrow the list of differentials for a particular case
(e.g., a true transudate might be associated with hypoalbuminaemia;
whereas an exudate could relate to bacterial sepsis). Morphological
assessment of the cells, e.g., neoplastic criteria or septic features,
is also part of a cytology report, with an overall comment and
suggestions as to further tests where appropriate.
2. Cutaneous/Subcutaneous Masses, Ulcerative Lesions
Advantages: relatively non-invasive, should not
require anaesthesia, easy to perform, pre-operative evaluation, e.g.,
knowledge that a mass is a Mast Cell Tumour before surgery may enable
the surgeon to plan the 3 cm margins, which are usually
recommended—both lateral and deep—to such a mass.
Disadvantages: may not always be diagnostic. In
these cases, we usually offer histopathology at 50% normal fee where a
cytology sample has already been processed.
3. Others
- Respiratory Tract Disease (direct pulmonary aspirates,
transtracheal washes, nasal flushes)
- Synovial fluid
- Prostate and direct aspirate, washing
- Urine sediments
- Diffuse organomegally (liver, spleen, kidney)
- Abdominal mass
- Lymphadenopathy
- Bone Marrow aspirate (must be combined with FBC for
interpretation).
Management of the Specimen
The dictum "garbage in - garbage out" is well applied to the
preparation of cytology specimens. Even the expert cytologist using
the best microscope cannot observe what is not there. We have
protocols available for fine needle aspirates, prostatic washes and
transtracheal washes. In addition, fluid samples are best submitted in
EDTA containers, and where sample volume permits, a second aliquot in
formal saline (1 drop per ml) might be helpful. If possible, an
air-dried smear prepared at collection might improve cell morphology.
Urine and prostatic specimens are best preserved in boric acid, rather
than EDTA, which inhibits bacterial overgrowth. For FNA, submission of
unstained smears is preferred.
We are always happy to discuss sampling techniques and sample
handling before collection.
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