Nervous system and Muscles Flashcards
- What is CSF cytology used for?
CSF cytology is used to assess metastatic or primary brain tumours or possible meningitis but the latter is diagnosed at microbiology. The macroscopic and microscopic investigations are both assessed Macroscopic investigation include the colour and consistency. Microscopic detection of any type of cells indicates a problem, CSF is normally acellular and any cells observed should be reported – including RBC, WBC, malignant cells.
- What are the microscopic and macroscopic features of CSF cytology?
Macroscopic – colour may be indicative of disease e.g. blood stained blood may be a sign of intracranial haemorrhage or incorrect sampling procedure (hitting a vessel)
Microscopy – should be acellular, the presence of any cells are noted including white cells, epithelial cells, malignant cells etc. The presence of red cells is not reported if suspected to be induced during sampling.
- How are nerve biopsies processed?
a. On the day of the surgical procedure the glutaraldehyde fixative is prepared. This is composed of 0.2M sodium cacodylate, 25% glutaraldehyde and distilled water.
b. Biopsy arrives in fresh saline wrapped in gauze it is registered
c. The nerve is spread out to its maximum length, typically around 4 centimetres then cut from the middle.
d. One piece (1.5-2cm) is placed in 10% NBF - processed in histology as normal, that is perform H&E stain, special stains such as congo red and immunostains e.g. myeline
e. The other half is place in 3% glutaraldehyde - packed with the request forms, case summary and covering letter and sent abroad for electron microscopy and expertise investigations.
- How are muscle biopsies processed?
Two pieces of muscle biopsies measuring 1cm3 are obtained. if the biopsy is for mitochondrial respiratory chain disorder, one biopsy is placed in dry ice with covering letter and case summary sent abroad for genetic testing. The other biopsy is kept for further studies at the laboratory and repeats.
A biopsy issued for investigation of myopathies or myositis is oriented transversely using a stereomicroscope, snap frozen at -80oC and processed. 50 slides are prepared – 25 slides with 1 section for histological stains and another 25 slides with 2 sections used for immunohistochemistry.
