Intraoperative cytology (squash smear) in neurosurgical practice - pitfalls in diagnosis experience based on 3057 samples from a single institution.
OBJECTIVE
The smear technique is challenging for a neuropathologist where rapid and accurate diagnosis is to be given on small biopsies. The present study, a large retrospective analysis of squash smears in neurosurgical practice, was conducted to assess the usefulness, accuracy and the diagnostic pitfalls of smear diagnosis.


METHODS
The authors analysed 3057 central nervous system (CNS) lesions sent for intraoperative cytology (IC) during the years 1988-2005. The stain used was 1% alcoholic toluidine blue. The smear diagnosis was compared with the histological diagnosis to evaluate the diagnostic accuracy.


RESULTS
Diagnostic accuracy irrespective of lesion and site ranged from 83.0% to 86.0% per year (mean=85%). The highest rate of correlation among common brain tumours was noted in schwannoma (96.6%) and pituitary adenoma (92.2%), followed by meningiomas (88.9%), astrocytomas (88.4%), chordomas (86.4%) and neurocytomas (86.9%). Infections as a whole contributed 380 cases. The most common infection was tuberculosis.


CONCLUSIONS
This is the largest series reported from India to the best of our knowledge. Squash smear technique is a very reliable and rapid method of intraoperative diagnosis. Knowledge of clinical and neuroimaging details helps the experienced neuropathologist to improve the diagnostic accuracy.
Goel
D
D
Department of Pathology, Nizam's Institute of Medical Sciences, Hyderabad, Andhra Pradesh, India.
Sundaram
C
C
Paul
T R
TR
Uppin
S G
SG
Prayaga
A K
AK
Panigrahi
M K
MK
Purohit
A K
AK
D016543:Central Nervous System Neoplasms / Q000175:diagnosis*; D003584:Cytological Techniques / Q000379:methods*; D006801:Humans; D007432:Intraoperative Period; D019635:Neurosurgical Procedures; D012189:Retrospective Studies; D012680:Sensitivity and Specificity