A Combined Cytomorphological and Immunocytochemical Approach in the Diagnosis of Cancers of Unknown Primary Origin

Abstract

Introduction: Unknown Primary Cancers (UPCs) present a major diagnostic challenge to both clinicians and pathologists. Hence, there is a strong need to effectively diagnose these cases. Aim: To study the cytological features of metastatic deposits from UPCs and the role of appropriate immunomarkers in identifying the primary site. Materials and Methods: This was a prospective descriptive study conducted between December 2012 to December 2015 in the Department of Pathology in JIPMER, Puducherry, India. Patients presenting with suspicious nodal or other probable metastatic deposits were subjected to Fine Needle Aspiration Cytology (FNAC). Morphologic features were studied and provisional/differential diagnosis were made, following which whenever essential, Immunocytochemistry (ICC) using appropriate panels of immunomarkers was performed on smears or cell blocks. Only the cases with subsequent histological/clinicoradiological correlation were statistically analysed by Statistical Package for Social Sciences (SPSS version 16.0) software and the distribution of data was expressed in frequencies and percentages and the p-value <0.05 was considered as significant level. Results: Out of total 224 cases of UPCs, 162 cases with subsequent follow-up were included in the study; 130 patients had histopathological follow-up, while 32 patients had only clinico-radiological follow-up. There was cytohistological concordance rate of 100% with a diagnostic accuracy of 95.4% for specific subtyping and a p-value of <0.0001. The maximum diagnostic accuracy for specific subtyping was noted with Squamous Cell Carcinomas (SCC), followed by Adenocarcinomas (ADC), miscellaneous diagnosis and lastly the Poorly Differentiated Carcinomas (PDC). Conclusion: This study demonstrated that a combined cytomorphological/immunocytochemical approach is highly effective in predicting the cell of origin and also the possible primary site of Cancer of Unknown Primary (CUP).

Keywords

• fine needle aspiration cytology
• immunocytochemistry
• metastatic deposits