Abstract

Background: Round Cell Tumors are heterogeneous malignancy featuring primitive undifferentiated small cell morphology. Small round cell tumors mostly occur in children, adolescents, and young adults. Because of their significant morphological overlap, have become a paradigm for an integrated approach to diagnosis. Immunohistochemistry (IHC) is the most common ancillary technique used for differential diagnosis of round cell tumors. Finding from all these studies are reviewed and interpreted in respect with clinical history, laboratory investigations, and diagnostic imaging finding.

Objectives: (i) To study the incidence, and age vs. sex wise distribution of round cell tumors. (ii) To study the Immunohistochemical (IHC) pattern of these different round cell tumors and correlate the morphological diagnosis with IHC to determine its role as a confirmatory or diagnostic marker of the round cell tumors.

Materials and Methods: As a part of study 75 (seventy-five) cases were selected during the year 2013-2015. Relevant findings were obtained. Biopsy tissues/ samples were fixed, paraffin embedded, sectioned and, stained with hematoxylin and eosin. IHC was performed on each case. Results were analyzed and compared.

Results: Out of 75 cases, there were 22 cases (29.33%) of Non-Hodgkin’s lymphoma with the highest incidence. According to age wise distribution, the highest incidence was observed in 0-10 years of age group. According to sex wise distribution, a higher incidence was observed in males. There were 50 cases (66.66 %) of Males and 25 cases (33.33%) of Females. Overall M:F ratio was 2:1. Based on IHC, 22 cases of NHL were further classified into Burkitt’s lymphoma, Lymphoblastic lymphoma, and Diffuse Large B-cell lymphoma. IHC study of PNET and Rhabdomyosarcoma showed CD 99(86.7%), NSE(73.3%) and Vimentin(100%) positivity and Desmin, Actin, CD 99 and Vimentin positivity respectively. IHC study of Neuroblastoma and medulloblastoma showed NSE, NF, Chromogranin, S 100 and Synaptophysin positivity and GFAP, Synaptophysin, Vimentin, and Ki67 positivity respectively.

Conclusion: Most frequent Round Cell Tumors are Non-Hodgkins Lymphoma, Neuroblastoma, Ewing/PNET and Rhabdomyosarcoma. Neuroblastoma, Retinoblastoma, Wilms Tumor, Hepatoblastoma show presentation in early childhood while Rhabdomyosarcoma is seen throughout childhood. The majority of round cells tumors have male predominance. This study emphasizes the role of immunohistochemistry (IHC) to arrive a definite diagnosis.

Key words: Small blue round cell tumors, Non-Hodgkin’s lymphoma, Small cell undifferentiated tumors, Embryonal tumors, Primitive tumors, Childhood solid tumors