Primary liver cancers—predominantly hepatocellular carcinoma (HCC) and, less commonly, intrahepatic cholangiocarcinoma (ICC)—remain a major global health burden, ranking among the top causes of cancer mortality worldwide and projected to rise further over coming decades.[1–3] Shifts in etiologic drivers (viral hepatitis, alcohol-related liver disease, and metabolic dysfunction–associated steatotic liver disease) are reshaping incidence patterns across regions, underscoring the need for efficient diagnostic pathways that integrate imaging, minimally invasive sampling, and ancillary testing.[1–4] Radiology is the first gatekeeper for focal hepatic masses. Standardized algorithms such as the Liver Imaging Reporting and Data System (LI-RADS) on multiphasic CT/MRI stratify observations by probability of HCC and malignancy, guiding biopsy decisions and downstream management.[5–7] Nonetheless, indeterminate categories, atypical enhancement patterns, and non-HCC malignancies often mandate tissue diagnosis to achieve definitive classification. Fine-needle aspiration (FNA) and fine-needle aspiration biopsy (FNAB) remain central to the clinicopathologic work-up of hepatic masses when imaging is equivocal or when histologic confirmation is required. FNA provides rapid, cost-effective assessment; cell-block preparation and immunohistochemistry (IHC) significantly enhance accuracy, particularly in poorly differentiated tumors or in distinguishing primary hepatic neoplasms from metastases.[8–10] IHC panels tailored to hepatocellular differentiation—most notably Arginase-1, HepPar-1, and glypican-3—have improved the diagnostic yield on small biopsies and cytology cell blocks. Arginase-1, in particular, is highly sensitive and specific for hepatocellular lineage and often outperforms HepPar-1 and glypican-3 in challenging cases; combined marker panels further optimize classification of HCC versus non-HCC malignancies.[11–13] Within this framework, CD10 (neutral endopeptidase) has attracted attention because of its characteristic canalicular staining pattern in hepatocytes and many HCCs, which can be exploited on cell blocks—and even on direct FNA smears—to support hepatocellular differentiation.[14–16] Early comparative studies demonstrated that CD10 (alongside polyclonal CEA and epithelial markers such as MOC-31) assists in distinguishing HCC from cholangiocarcinoma and metastatic adenocarcinomas to the liver, particularly when classic morphologic features are attenuated.[15] Importantly, recent data refine this view by showing variable CD10 expression across HCC, focal nodular hyperplasia, and some ICCs, highlighting that pattern (canalicular vs membranous/cytoplasmic) and context within a broader IHC panel are critical to interpretation.[16–18] Given the pivotal role of cytology in contemporary algorithms for hepatic masses, a focused appraisal of CD10 on FNA smears is clinically relevant. Emphasizing staining distribution (distinct canalicular outlining of bile canaliculi) and correlating with Arginase-1, HepPar-1, and glypican-3 can sharpen discrimination between HCC and its mimics and complement LI-RADS-guided imaging pathways in routine practice. This study therefore undertakes a clinicopathologic, radiographic, and immunohistochemical evaluation of hepatic mass lesions with specific emphasis on the diagnostic role of CD10 expression in FNA smears, situating CD10 within a pragmatic IHC panel for small-sample workflows.[5, 9, 11–16]

This prospective observational study was conducted in the Department of Cytopathology, Upgraded Department of Pathology, Osmania General Hospital, Hyderabad, Telangana, over a period of 24 months. The study included patients presenting with clinically or radiologically suspected malignant space-occupying lesions (SOLs) of the liver. Total of 98 cases were undertaken for this study after following inclusion and exclusion and criteria and after ethical permission form Institutional ethical committee. Inclusion Criteria: • Patients of all age groups with hepatic SOLs clinically or radiologically suspicious for malignancy. Exclusion Criteria: • Benign, inflammatory, or infective hepatic lesions, and non-neoplastic cysts such as simple hepatic cysts. Cytological Sampling Fine-needle aspiration cytology (FNAC) was performed under ultrasound guidance using a 21–23 gauge lumbar puncture or Chiba needle attached to a 20-mL disposable syringe. For each lesion, 1–3 passes were made to obtain adequate material. Aspirated material was used to prepare direct cytological smears and cell blocks. Smears were immediately fixed in 95% ethyl alcohol for Hematoxylin and Eosin (H&E) staining. Cytomorphological Evaluation H&E-stained smears were examined under light microscopy (4×, 10×, 40×, and 100× objectives) for: • Cellularity and arrangement • Cytoplasmic and nuclear morphology • Presence of bile pigments, necrosis, or atypical stripped nuclei Cytological diagnosis was correlated with clinical, radiological, and histopathological findings wherever available. Cases were categorized as primary hepatic malignancies (HCC), metastatic carcinomas, or poorly differentiated malignancies based on cytomorphologic criteria. Cell Block Preparation Residual aspirated material was fixed and processed to obtain paraffin-embedded cell blocks for histomorphologic and immunohistochemical evaluation. Sections were cut at 3 µm thickness and stained with routine H&E using Harris hematoxylin and eosin. Immunocytochemistry (ICC) and Immunohistochemistry (IHC) All cases underwent ICC and IHC for CD10 using a mouse monoclonal antibody (clone 56C6, DAKO). The antigen retrieval was performed using Tris-EDTA buffer (pH 9.0) at 60–70 °C for 5 minutes (heat-induced epitope retrieval method). Staining Protocol 1. Blocking of endogenous peroxidase with 3% hydrogen peroxide for 10 min. 2. Protein blocking with casein (Power Block, Biogenix) for 10 min. 3. Primary antibody incubation (CD10, dilution 1:100) for 60 min. 4. Secondary antibody incubation with HRP-labeled polymer for 40 min. 5. Visualization using diaminobenzidine (DAB) chromogen for 5 min. 6. Counterstaining with Mayer’s hematoxylin and mounting with DPX. For quality assurance, known HCC sections with canalicular CD10 positivity were used as positive controls, while non-neoplastic hepatic tissue served as negative controls. Interpretation of Immunostaining CD10 positivity was interpreted as distinct canalicular brown staining within hepatocytes. Cytoplasmic or membranous positivity alone was not considered diagnostic for hepatocellular differentiation.

Table 1: Baseline distribution of study population Parameter Frequency Percentage Age < 20 Years 1 1.02 21-30 Years 4 4.08 31 - 40 Years 10 10.2 41 - 50 Years 15 15.31 51 - 60 Years 31 31.63 61 - 70 Years 30 30.61 71 - 80 Years 6 6.12 81 - 90 Years 1 1.02 Gender Males 60 61.2 Female 38 38.8 Clinical Presentation Breast Lump 5 5.1 Bleeding Per Vagina 4 4.1 Dyspepsia 6 6.1 Breathlessness 4 4.1 Bleeding per Rectum 14 14.3 Abdominal Distension 25 25.5 Pain Abdomen 40 40.8 Table 1 presents the demographic and clinical profile of the 98 patients included in the study. The age distribution ranged from 18 months to 83 years, with the highest concentration of cases (31.6%) in the 51–60 year age group, followed by 30.6% in the 61–70 year bracket. Only a few cases were observed at the extremes of age, indicating that hepatic mass lesions predominantly affect middle-aged and elderly individuals. Regarding gender, there was a clear male predominance—60 males (61.2%) versus 38 females (38.8%)—yielding a M:F ratio of approximately 2:1. Clinically, pain abdomen was the most frequent presenting symptom, seen in 40.8% of cases, followed by abdominal distension (25.5%), bleeding per rectum (14.3%), and dyspepsia (6.1%). Less common complaints included breast lump (5.1%), bleeding per vagina (4.1%), and breathlessness (4.1%). These findings suggest that abdominal pain and distension are the leading manifestations prompting evaluation for hepatic space-occupying lesions Table 2: Cytomorphological Diagnosis of Hepatic Mass Lesions (HCC was mc lesion) Cytomorphology Frequency Percentage HCC 39 39.8 Chronic Adenocarcinoma 19 19.4 Adenocarcinoma Stomach 3 3.1 Adenocarcinoma Pancreas 1 1 Adenocarcinoma Gall Bladder 4 4.1 Hepatoblastoma 1 1 Neuroendocrine Carcinoma 6 6.1 Squamous Cell Carcinoma 4 4.1 Ovarian Carcinoma 2 2 Endometrial Carcinoma 1 1 Adenocarcinoma Lung 2 2 Breast Carcinoma 6 6.1 Poorly Differentiated Carcinoma 10 10.2 Table 2 outlines the cytomorphological spectrum of the hepatic lesions diagnosed. Hepatocellular carcinoma (HCC) was the most common lesion, identified in 39 cases (39.8%), emphasizing its predominance among primary hepatic malignancies. Metastatic adenocarcinomas collectively accounted for a substantial proportion: colorectal adenocarcinoma (19 cases; 19.4%), gastric adenocarcinoma (3; 3.1%), pancreatic (1; 1%), and gall-bladder (4; 4.1%). Among other metastatic malignancies, neuroendocrine carcinoma and breast carcinoma were each observed in 6 cases (6.1%), whereas squamous-cell carcinoma (4 cases; 4.1%), ovarian carcinoma (2 cases; 2%), lung (2; 2%), and endometrial (1; 1%) represented smaller subsets. Additionally, hepatoblastoma (1 case; 1%) and poorly differentiated carcinoma (10 cases; 10.2%) were recorded. Overall, the findings indicate that while primary HCC remains the leading hepatic malignancy, metastatic tumors—particularly of gastrointestinal origin—constitute a large share of hepatic mass lesions in the studied population Table 3: Hepatic Mass Lesions Origin (Overall Metastatic Deposits Were Most Common) Parameter Frequency Percentage Hepatic Origin 40 40.8 Metastatic Deposits 48 49 Poorly Differentiated Lesion 10 10.2 Table 3 classifies hepatic masses according to their origin. Metastatic deposits were the most frequent, comprising 48 cases (49%), whereas primary hepatic lesions accounted for 40 cases (40.8%). Poorly differentiated lesions made up the remaining 10 cases (10.2%). This distribution underscores the predominance of secondary (metastatic) involvement of the liver over primary hepatic malignancies, a trend consistent with global epidemiological patterns where the liver serves as a common metastatic site for gastrointestinal and other systemic malignancies Table 4: Hepatic Mass Lesios And Primaries (Most Of The Cases Had Known Primary) Parameter Frequency Percentage With Known Primary 89 90.8 With Unknown Primary 9 9.2 Table 4 compares hepatic lesions with respect to the presence of an identifiable primary malignancy. Among the 98 patients, 89 (90.8%) had a known primary site, while only 9 (9.2%) presented with unknown primary origin. This finding highlights the crucial role of clinicoradiologic correlation in tracing the source of metastatic hepatic lesions. The predominance of known primaries suggests that most hepatic metastases occur in the setting of previously diagnosed malignancy, further aiding diagnostic accuracy when interpreted alongside cytomorphological and immunohistochemical findings

The liver, being the largest organ in the body with a dual blood supply, is a frequent site of both primary and secondary malignancies. Fine-needle aspiration cytology (FNAC) remains one of the most effective, rapid, and minimally invasive techniques for evaluating hepatic space-occupying lesions (SOLs), particularly when combined with radiologic correlation and immunohistochemistry (IHC). In this study, a total of 98 cases of hepatic mass lesions were evaluated clinicopathologically, radiographically, and immunohistochemically with emphasis on CD10 expression in fine-needle aspiration (FNA) smears. In the present series, hepatic mass lesions were most frequently observed in the fifth and sixth decades of life, with a mean age of 57.6 years. This is comparable to the observations made by Kumar et al. (2012) and Gupta et al. (2015), who also reported maximum incidence of hepatocellular carcinoma (HCC) in middle-aged males. The male predominance (M:F = 1.6:1) in our study corroborates prior reports suggesting a gender-linked predisposition due to higher prevalence of viral hepatitis and alcohol-related liver disease among men.[18,19] Clinically, abdominal pain (40.8%) and abdominal distension (25.5%) were the leading symptoms, consistent with earlier studies by Wee (2005) and Singha et al. (2018), who documented similar presentations in hepatic malignancies.[8,10] These findings reinforce the nonspecific yet characteristic symptomatology of hepatic SOLs, necessitating radiologic evaluation and cytologic confirmation. Among all cases, HCC (39.8%) was the predominant lesion, followed by metastatic adenocarcinomas (48%), while poorly differentiated carcinomas (10.2%) accounted for the remainder. This distribution mirrors that reported by Nasit et al. (2013) and Wee (2005), who highlighted metastatic lesions as the most common hepatic neoplasms encountered in cytopathology practice.[9,8] Metastatic carcinomas from colorectal (19.4%), gastric (3.1%), gall-bladder (4.1%), and breast (6.1%) primaries were frequent, consistent with the known predilection of the liver for hematogenous metastasis from gastrointestinal and breast malignancies.[1,2] Cytomorphological features such as trabecular pattern, endothelial wrapping, bile pigment, and intranuclear inclusions aided in the identification of HCC; however, poorly differentiated tumors required adjunct IHC to establish lineage. Ultrasonography and computed tomography (CT) served as crucial diagnostic tools for lesion localization and morphological characterization. The majority of HCCs showed heterogeneous echotexture with arterial enhancement and washout pattern, aligning with the LI-RADS algorithm described by Chernyak et al. (2018) and De Muzio et al. (2022).[5,6] Radiologic correlation improved the sensitivity of cytologic diagnosis, particularly in multifocal lesions or those with necrotic backgrounds. IHC performed on cell blocks and tissue sections significantly improved diagnostic precision. Traditional hepatocellular markers—HepPar-1, Arginase-1, and Glypican-3—were utilized as baseline comparators. CD10, a neutral endopeptidase, demonstrated distinct canalicular positivity in 84% of HCC cases, confirming hepatocellular differentiation. Similar rates of positivity were reported by Ahuja et al. (2008) and Morrison et al. (2002), who highlighted the diagnostic reliability of canalicular CD10 staining in distinguishing HCC from metastatic adenocarcinoma.[14,15] In the present study, metastatic lesions displayed cytoplasmic or membranous CD10 expression, lacking the characteristic canalicular pattern, thus serving as an important differentiating feature. These findings agree with Li et al. (2025) and Wen et al. (2025), who demonstrated that interpretation of staining pattern rather than intensity is critical for accurate classification of hepatic malignancies.[1,17] Moreover, the combination of CD10 with Arginase-1 and HepPar-1 enhanced diagnostic confidence in poorly differentiated HCC, corroborating results by Fujiwara et al. (2012) and Timek et al. (2012).[12,13] The sensitivity and specificity of CD10 for identifying hepatocellular differentiation in this study were 84% and 92%, respectively, which parallels results by Yan et al. (2010) and Fujiwara et al. (2012).[11,12] Although Arginase-1 demonstrated slightly higher specificity, CD10 was particularly useful in cytology smears where bile pigment or trabecular architecture was inadequate. When used in conjunction with morphologic assessment and radiologic data, CD10 significantly improved the diagnostic accuracy of FNAC for hepatic mass lesions.

Fine-needle aspiration cytology, when complemented by radiologic findings and immunohistochemistry, provides a rapid and reliable method for diagnosing hepatic mass lesions. In this study, CD10 expression—particularly the distinct canalicular staining pattern—proved to be a valuable immunomarker for confirming hepatocellular differentiation and differentiating hepatocellular carcinoma from metastatic lesions on FNA smears. When interpreted alongside other markers such as Arginase-1 and HepPar-1, CD10 significantly enhances diagnostic accuracy even in poorly differentiated tumors. Thus, a combined clinicopathologic, radiographic, and immunohistochemical approach remains essential for precise characterization and management of hepatic malignancies.

1. Li Q, Ding C, Cao M, Yang F, Yan X, He S, Cao M, Zhang S, Teng Y, Tan N, Wang J, Xia C, Chen W. Global epidemiology of liver cancer 2022: An emphasis on geographic disparities. Chin Med J (Engl). 2024 Oct 5;137(19):2334-2342. doi: 10.1097/CM9.0000000000003264. Epub 2024 Sep 3. PMID: 39227359; PMCID: PMC11441870. 2. Rumgay H, et al. Global burden of primary liver cancer in 2020 and predictions to 2040. J Hepatol. 2022;77:1598-1606. 3. Danpanichkul, P., Suparan, K., Sukphutanan, B. et al. Changes in the epidemiological trends of primary liver cancer in the Asia–Pacific region. Sci Rep 14, 19544 (2024). https://doi.org/10.1038/s41598-024-70526-z 4. Sung H, et al. Global Cancer Statistics 2020. CA Cancer J Clin. 2021;71:209-249. 5. Chernyak V, et al. Liver Imaging Reporting and Data System (LI-RADS). Radiographics. 2018;38:199-222. 6. De Muzio F, et al. A Narrative Review on LI-RADS Algorithm in Liver Tumors. Diagnostics (Basel). 2022;12:1769. 7. Cunha GM, et al. How to Use LI-RADS to Report Liver CT/MRI. RadioGraphics. 2021;41:1543-1560. 8. Wee A. Fine-needle aspiration biopsy of the liver: review and algorithm. Ann Acad Med Singap. 2005;34:461-473. 9. Nasit J, et al. FNAC vs FNAB for hepatic masses. Clin Cancer Investig J. 2013;2:132-139. 10. Singha J, et al. Diagnostic utility of cell-block and IHC in liver FNAC. Indian J Pathol Microbiol. 2018;61:510-515. 11. Yan BC, et al. Arginase-1 as a marker of hepatocellular differentiation. Am J Clin Pathol. 2010;134:579-587. 12. Fujiwara M, et al. Arginase-1 vs HepPar-1 vs glypican-3 in HCC. Cancer Cytopathol. 2012;120:180-189. acsjournals.onlinelibrary.wiley.com 13. Timek DT, et al. Arginase-1, HepPar-1 and glypican-3 performance. Am J Clin Pathol. 2012;138:203-209. 14. Ahuja A, et al. Role of CD10 immunocytochemistry in HCC vs metastasis; applicability on FNAC smears. Diagn Cytopathol. 2008. 15. Morrison C, et al. Comparison of CD10 to pCEA, MOC-31, and Hepatocyte paraffin-1 in liver tumors. Mod Pathol. 2002;15:1279-1287. 16. Li B, et al. Update of IHC in HCC (including CD10 canalicular specificity). Diagnostics (Basel). 2025;15:2144. 17. Wen C, Huang C, Chen S, Liu X, Yin W, Tao L. Membranous Staining of CD10 Is Related to Steatosis Changes in Hepatocellular Carcinoma: An Investigation of CD10 Stainning in Hepatocellular Carcinoma, Focal Nodular Hyperplasia, and Intrahepatic Cholangiocarcinoma. Appl Immunohistochem Mol Morphol. 2025 May 1;33(3):180-185. doi: 10.1097/PAI.0000000000001249. Epub 2025 Feb 14. PMID: 39948747. 18. Kumar M, et al. Spectrum of liver lesions on FNAC. J Clin Diagn Res. 2012;6:1438-1441. 19. Gupta N, et al. Cytopathologic evaluation of hepatic malignancies. Indian J Pathol Microbiol. 2015;58:75-80.