DIAGNOSTIC CHARACTERISTICS OF ADRENAL TUMORS: A COMPARATIVE ANALYSIS OF ADENOMA, PHEOCHROMOCYTOMA, AND ADRENOCORTICAL CARCINOMA

Abstract

Adrenal tumours encompass morphologically and biologically diverse lesions that require careful pathological distinction. This study compared the clinicopathological, histomorphological, immunohistochemical, tissue staining, and molecular characteristics of adrenocortical adenoma, pheochromocytoma, and adrenocortical carcinoma (ACC) using secondary pathological datasets and representative H&E images. Adrenocortical adenoma showed clear to finely vacuolated cortical cells with relatively organized architecture, while ACC demonstrated markedly larger tumour size and lower tissue staining indices. Median tumour size was 2.85 cm in adenoma and 9.50 cm in ACC, with a significant difference between groups. Pheochromocytoma exhibited characteristic nested or alveolar architecture with vascular stroma and showed considerable pathological heterogeneity. Median PASS and GAPP scores were both 6.0, vascular invasion occurred in 20.0% of lesions, distant metastasis in 14.3%, and SDHB loss in 11.4%. Cross-tumour analysis demonstrated significant differences in TMA CTCF, qPCR expression, and ELISA-derived concentrations among normal/control, adenoma, pheochromocytoma, and ACC groups. These ancillary findings supported the distinct biological profiles of the three tumour categories but were interpreted as complementary to conventional microscopy. Representative microscopy further highlighted lineage-specific cellular architecture, reinforcing the diagnostic value of direct tissue assessment alongside quantitative pathological and molecular measurements in practice. Overall, the findings support a pathology-first diagnostic framework integrating histomorphology with clinicopathological and immunohistochemical evidence to improve differentiation of major adrenal tumour types and characterize features associated with malignant potential and biological behaviour.