Immunocytochemistry in the diagnosis of small blue cell tumours of childhood

Abstract

Objective: This study attempts to define a limited, cost effective, reliable primary panel of antibodies for immunohistology, as an adjunct to morphological features, for the diagnosis of Small Blue Cell Tumors (SBCT) which would be convenient for use in low resource settings to improve their diagnostic accuracy. The choice of antibodies is based on the common childhood tumors in Ibadan and limited by financial constraints and availability of antibodies. Materials & methods: Twenty-five representative cases of previously diagnosed small blue cell tumours of childhood were selected from the file of the Department of Pathology, University College Hospital, Ibadan. The retrieved blocks were cut and stained with antibodies to desmin, leucocyte common antigen, cytokeratin, chromogranin, neuron-specific-enolase, vimentin and neurofilament using the avidin-biotin technique as previously described. Results: Of the 25 cases studied 24 (96%) gave interpretable immunostaining reaction and the immunophenotype of these were defined. The staining quality equaled that produced on the control well-fixed positive control sections. The final diagnosis of six of the 25 cases changed based on immunostaining. Four cases previously diagnosed as lymphoma were confirmed to be rhabdomyosarcoma (3 cases) and neuroblastoma, one case each of rhabdomyosarcoma and neuroblastoma were both reclassified as lymphoma. Conclusion: Based on our findings, the use of a small first-line panel of antibodies to leucocyte common antigen, desmin and neuron-specific-enolase are ideal for immunohistochemical discrimination of SBCT, as an adjunct to morphology, in low-resource settings.