Correlation of morphologic and biochemical observations in human lipomas.

Our studies of 107 patients with 133 lipomata showed that the male to female ratio for single lipoma was 1.2:1, and for multiple lipoma it was 3.5:1. More than 40% of the men and 30% of women with multiple lipoma had a family history of lipoma. Specimens from 23 patients were analyzed for lipid and protein content. Adipose tissue from lipoma had somewhat more lipid per gram of wet weight than adjacent normal tissue (75.0 versus 72.8%) or 16 additional control adipose tissue samples, from patients undergoing elective abdominal surgery (71.5%), but the differences were not statistically significant (p = 0.085). There were no differences in protein content. In 13 men the lipoprotein lipase activity of lipoma was markedly higher compared with the adjacent normal adipose tissue (40.4 +/- 15.5 versus 14.0 +/- 11.7 nmoles/gm/minute at 37 degrees C, p = 0.001) or to control adipose tissue (9.6 +/- 7.2 nmoles of free fatty acid/gm/minute at 37 degrees C, p = 0.001). It is likely that the high lipoprotein lipase activity of lipoma contributes to the growth of the tumor. Morphologically, there were no clear distinguishing features between the adipocytes of lipoma, adjacent normal adipose tissue, or control adipose tissue. However, the numbers of more immature type or preadipocytes (mesenchymal cells) appeared to be more numerous in lipomata compared with the control tissues. No differences in immunologic reactivity could be detected using antisera to fat cell membranes from lipoma or control adipose tissue.