Intra-abdominal lymphangiomas in children and adults. Assessment of proliferative activity.

OBJECTIVE: Intra-abdominal lymphangiomas are rare in children and even more exceptional in adults. Because these lesions occasionally progressively enlarge, we analyzed seven adult and four pediatric cases for evidence of proliferative activity.
DESIGN: Immunohistochemical analysis was performed retrospectively on representative tissue sections using antibodies to the following antigens: Ki-67, proliferating cell nuclear antigen, and p53 gene product (eight cases). DNA ploidy was examined in five cases. PATIENTS: The study group consisted of seven adult women (aged 24 to 73 years), a 3.5-year-old girl, and two boys, aged 3.5 and 9 years, the last with a recurrence at age 15. The lymphangiomas ranged from 1.7 to 23 cm in maximum size.
RESULTS: Ranges of percentages of cells staining for proliferating cell nuclear antigen, Ki-67, and p53 were similar between the pediatric and adult cases. Antibody to Ki-67 stained from 0.5% to 17% of the stromal and endothelial components of the lymphangiomas. Proliferating cell nuclear antigen activity was noted in 16% to 52% of lesional cells. Reactivity was noted almost exclusively in areas of inflammation and fibroplasia. For comparison, 10% to 50% of intermixed lymphocytes stained for Ki-67 and proliferating cell nuclear antigen. There was no labeling with p53. DNA content was uniformly diploid.
CONCLUSIONS: The scant staining for Ki-67 in the majority of the lesions, combined with proliferative rates that were only focally elevated, suggests that lymphangiomas in children and adults are quiescent lesions whose enlargement is due to engorgement by chyle and localized secondary inflammation rather than primary tumoral growth.