Immunocytochemistry: It's role in diagnosis of undifferentiated neoplasms by fine needle aspiration cytology

BACKGROUND: Fine needle aspiration cytology (FNAC) is a rapid, cheap and reliable method for diagnosing any accessible lesion. However, there remains a group of malignant undifferentiated neoplasms, which can only be categorized with the help of immunocytochemistry (ICC). The categorization is important due to their vast difference in treatment and prognosis. AIM: To evaluate the effectiveness of ICC in categorizing the undifferentiated neoplasms diagnosed on routine FNAC smears. MATERIALS AND METHODS: Thirty six cases of undifferentiated neoplasms were selected from a group of total 78 cytology cases of undifferentiated tumors from different sites like head and neck, lymph node, soft tissue etc. These were then subjected to a panel of ICC markers based on the clinical and cytomorphological features. RESULTS: Of these, 21 were simple, ten were computerized tomography guided and five were ultrasound guided FNACs respectively. All the 78 cases were confirmed by histopathological examination and immunohistochemistry. Of the 36 cytological cases, final diagnosis correlated in 30 cases histologically. The six cases were incorrect either due to inadequate material on the smears (three cases) or false positive staining (three cases). CONCLUSIONS: Our study found that ICC is a sensitive and specific method for early and definitive diagnosis of undifferentiated neoplasms. However, selection of antibodies must be judicious to make it cost effective.