Role of Immunohistochemistry in Categorisation of Metastatic Tumours of Liver: A Cross-sectional Observational Study

Abstract

Introduction: The liver is the body’s largest solid organ and receives a dual blood supply, making it an easy target for metastases from both extra-abdominal and abdominal lesions. In adults, the most common sites of primary lesions are the breast, colon, lung and pancreas. Liver biopsies are pivotal for managing patients with metastatic diseases, aiding in diagnosis and treatment planning. When primary cancer sites are undetectable, the diagnosis often falls under Carcinoma of Unknown Primary (CUP), which carries a poor prognosis. Immunohistochemistry (IHC) is critical in such cases, using antibodies to identify the cancer’s origin when other methods fail. This technique is vital for confirming known malignancies and diagnosing elusive ones, thus informing treatment and improving patient outcomes. Aim: To study the role of IHC in the categorisation of metastatic tumours of the liver. Material and Methods: A cross-sectional observational study was conducted in the Department of Pathology, Sri Aurobindo Medical College and Postgraduate (PG) Institute, Indore, Madhya Pradesh, India, between March 2021 and April 2024. Core needle biopsy samples of 65 cases were processed and analysed for Haematoxylin and Eosin (H&E) stain and IHC markers. Data on demographics and lesion characteristics were entered into Microsoft Excel and analysed with a trial version of Statistical Package for the Social Sciences (SPSS). Significance was assessed using Pearson’s Chi-square test, with a p-value<0.05 considered statistically significant, and IHC findings were compared with radiological data. Results: The mean±Standard Deviation (SD) age of the study participants was 54.26±11.858 years. During the study period, 65 cases were recorded, with a slight female preponderance (n=34) over males. Hepatomegaly (n=23) was the most common clinical finding noted. All cases were grouped according to the radiological findings with reference to whether the primary site of the lesion was known or unknown. Twenty-seven cases had a known primary lesion, while 38 cases were classified as unknown. Accordingly, an IHC marker panel of Cytokeratin 7 (CK7) and Cytokeratin 20 (CK20) was initially applied, followed by the respective organ specific markers. With respect to all 65 cases, a concordance of 98.46% was recorded with the radiological findings, while a discordance of 1.54% was noted. A p-value<0.05 suggested that both IHC and the radiological findings regarding the nature of the primary lesion, whether known or unknown, were significant. Conclusion: Immunohistochemistry is paramount in ascertaining the origin of the primary lesion in hepatic metastatic tumours, which is crucial for prompt therapeutic intervention and favourable patient outcomes. The integration of IHC with radiological data is essential for accurate diagnosis and treatment plans.

Keywords

• abdominal lesions
• malignancies
• radiology
• unknown primary