Evaluation of Imprint (touch smear) Cytology as a Diagnostic Tool in Central Nervous System Tumours at the Kenyatta National Hospital

Abstract

Cytology is a useful adjunct to frozen section examination when multiple rapid samples are available or when superior cytological detail is required. Cytological analysis can be used in place of frozen section examination when rapid diagnosis is desired by the surgeon so that appropriate management can be effected. In this way imprint/smear cytology is reliable, rapid and inexpensive method of diagnosis which can be employed in intra operative diagnosis and management of cases, thereby providing immediate cytological diagnosis. To introduce and evaluate the Diagnostic Accuracy of Imprint Cytology of Central Nervous System tumours at the Kenyatta National Hospital when compared to conventional histopathology. This was a six-month descriptive prospective study of specimens from patients undergoing surgery for cenyal nervous system tumours at the Kenyatta National Hospital. Diagnostic details from imprint/smear cytology were compared with those obtained from histopathological analysis. A total of seventy one (71) patients were sampled and included in the study. Their radiological and clinical diagnoses were studied. Smear (imprint touch) cytological findings were compared with those of histology which has been considered the gold standard of diagnosis, i.e confirmatory. Of these meningiomas, were the most frequently diagnosed, cytologically accounting for 40.8%(29 cases) followed by astrocytomas26.8%(19cases) figure 1 and table 9. Tumour cysts lesions accounted for 7%. Other diagnosed cases were like adenomas, medulloblastomas, tuberculomas. However four lesions were inconclusive in this diagnostic modality. The overall accuracy rate was found to be eighty four point five (84.5) percent while in case of meningioma was 96.7% and astrocytomas was 82.6%. The sensitivity and specificity of this modality of investigation was 98.3% and 85.7% respectively. The level of association was significant in all variables with P value< 0.05. So was the spearman correlation index. Imprint/smear cytology can be employed as a modality of providing a provisional diagnosis hence assisting in intra-operative and immediate post-operative management for most CNS tumours.