Use of Immunohistochemistry in the differential diagnosis of Small Round Blue cell tumors.
Objectives: Objective of the study is to differentiate and sub-categorize malignant small round blue cell tumors by using immune-histochemistry. Study Design: Descriptive Observational study. Setting: Meezan Private Lab, Faisalabad, Pakistan. Period: 5 years, from July 2014 to June 2019. Material & Methods: Sample Size: 126 cases of Round blue cells tumors. Sampling Technique: Non probability purposive sampling. Data Collection Procedure: 126 cases which fulfilled the inclusion and exclusion criteria were selected for the study. All these cases were subjected to immunohistochemistry. The IHC technique used was based on Peroxidase anti-peroxidase (PAP) method. Based on site and morphological clues, initially Leukocyte common antigen (LCA), Myogenin, Cytokeratin (CK), Desmin, chromogranin, Neuron specific enolase (NSE), S-100, Smooth muscle actine (SMA) and CD99 were used. Further immune stains panels were used afterwards, as and when needed like CD20, CD3, CD30, BCL2, CD117, Ki-67, Tdt, synaptophysin, SMA, CD56, Melan A, HMB45 and WT1. Results: Out of 126 cases of small round blue cell tumors, 35 (27.8 %) cases were diagnosed as diffuse large B cell lymphoma, 6 as Lymphoblastic lymphoma, 4 as Burkitt’s lymphoma, and 6 cases as NK/T cell lymphoma. Ewing’s sarcoma/PNET (12/126, 9.5%) was the 2nd highest in frequency, followed by Rhabdomyosarcoma, Synovial sarcoma, Malignant melanoma, and Germ cell tumor, which were all 9/126 each with 7.1 %. Conclusion: Immunohistochemistry is an important tool for appropriate and clear differential diagnosis of malignant small round blue cell tumors of childhood.