OBJECTIVETo study the nature of the residue hard tissue after liposuction in lipoma and its role in lipoma recurrence.

METHODSThe residue hard tissue after liposuction was collected for histologic study, including HE-staining and immunohistochemistry with antibody of stem cell marker (CD29 and CD44). The average density and area of positive cells were analyzed statistically.

RESULTSThe residue hard tissue had a medium hardness. The center tissue was light yellow surrounding by soft, loose, irregular and cord-like tissue. The normal fat tissue is light yellow with a soft and unanimous texture. HE-staining showed abundant stromas in residue hard tissue, with lots of fibroblast-like cells locating among adipocytes. The cytoplasm was less with large and blue-staining nucleus. In normal fat tissue, the fat cells were uniform which were round or polygon. The stromas was less and the fibroblast-like cells were comparatively less. The slices were stained with antibody (CD29, CD44) of stem cell marker. The density and area of positive cells were much more in residue hard tissue than those in normal adipose tissue. Two Independence Samples T test were as follows: (t'CD29 = 9.931, P = 0.000; (t'CD44 =10.171, P = 0.000 for density; and (t'CD29 = 7.761, P = 0.000; tt'CDRR = 6.639, P = 0.000 for area. The difference was significant.

CONCLUSIONSAbundant fibroblast-like cells that are signed by the marker of stem cells exist in residue hard tissue. Those cells are proven to be lipoma derived stem cells (LDSCs) which may play an role in lipoma recurrence after lipoma liposuction.