CONGENITAL MELANOCYTIC NEVI AND DNA CONTENT - AN ANALYSIS BY FLOW ANDIMAGE CYTOMETRY

Background. Potential risk factors for the development of melanoma in congenital melanocytic nevi (CMN) are not well established. DNA aneupl oidy may constitute such a risk factor but has not been sufficiently s tudied in CMN. Methods. In the present study, DNA analysis of eight gi ant CMN, nine medium CMN (1.5-20 cm), and eight small CMN (< 1.5 cm) w as assessed by flow cytometry and selected lesions (six nevi)by DNA im age cytometry. DNA content was correlated with patient age, nevus size , and degree of cytologic atypia. Results. DNA aneuploidy was detected by flow cytometry in two giant CMN from adult patients and in a small CMN from a child. DNA aneuploidy was not observed in any of the six C MN studied by image cytometry, although an increased S-phase was noted in a markedly atypical giant CMN. No DNA aneuploidy was detected in m edium-sized CMN or in the CMN of nine patients 1 year of age or younge r. Conclusion. In contrast to previous studies, it was observed that a bnormal DNA content does tend to correlate with cytologic atypia, part icularly in giant CMN with atypia or melanoma, in adults. Conversely, frank DNA aneuploidy in any CMN in children younger than 1 year of age , irrespective of histologic findings, was not detected. Finally, base d on these limited studies, greater sensitivity of image over flow cyt ometry for detection of DNA aneuploidy cannot be verified.