NEOPLASTIC PROGRESSION IN THE ADRENAL CORTEX IS BETTER DEFINED BY DNA AND PROLIFERATION HETEROGENEITY

Background: Monoclonal adrenal cortical lesions show inverse correlation between proliferation and apoptosis, while proliferation is the single most important criterion of malignancy in adrenal lesions. No study evaluates the variability of proliferation regarding the clonal pattern and diagnosis in adrenal cortical nodular hyperplasias (ACNH), adenomas (ACA), and carcinomas (ACC).
Methods: We studied 20 ACNII, 25 ACA, and I0 ACC (WHO criteria) from 55 females. Representative samples were histologically evaluated and microdissected to study clonality by X-chromosome inactivation. DNA content and proliferation were evaluated in consecutive sections by slide and flow cytometry, and the mitotic index was studied in 50 HPF from the same area. The percentage of non- octaploid cells with DNA content exceeding 5c (ScER) and the standard deviation of the mitotic figure counting per HPF (MFC/HPF) were used to define heterogeneity. Appropriate tissue controls were run in every case. Variables were statistically tested by analysis of variance and Student t-test regarding the clonal patterns and diagnosis.
Results: Polyclonal patterns were observed in 14/18 informative ACNH and 3/22 informative ACA, and monoclonal in 4/18 ACNH, 19/22 ACA, and 9/9 ACC. All hyperdiploid lesions (6 ACC and 5 ACA) revealed monoclonal patterns. The standard deviation of MFUHPF significantly increased in the sequences ACNH-ACA-ACC (0.04810.076, 0.1lOi0.097, 0.506i0.291; P=0.0023), but did not differentiate between polyclonal and monoclonal benign lesions. Only the percentage of tetraploid cells (P=0.0496) and 5cER (P=0.0352) distinguished polyclonal (7.2517.52 and 1.0011.74, respectively) from monoclonal (3.6412.20 and 0.14iO.15) benign lesions. Malignancy in monoclonal lesions significantly correlated with lower percentage of diploid cells and higher percentage of tetraploid cells as well.
Conclusions: Heterogeneity is the hallmark of cell kinetics during the neoplastic transformation of adrenal cortical cells. Monoclonal lesions are characterized by the accumulation of tetraploid and hypertetraploid cells, suggesting non-disjunctional mitoses. ACCs additionally reveal heterogeneously distributed proliferating cells and decreased proportion of euploid cells.