DISTRIBUTION OF BASEMENT-MEMBRANE COMPONENTS IN NORMAL ADIPOSE-TISSUEAND IN BENIGN AND MALIGNANT-TUMORS OF LIPOMATOUS ORIGIN

Normal adipose tissue as well as 13 benign and 17 malignant lipomatous tumors (Lipomas, hibernomas, lipoblastomas, and liposarcomas) were im munohistochemically analyzed for their expression of the basement memb rane components collagen IV, laminin, heparan sulfate proteoglycan, an d fibronectin. Monovacuolar cells in normal white fat tissue and in li pomas generally exhibited a distinctive pericellular basement membrane composed of collagen IV and laminin, whereas heparan sulfate proteogl ycan and fibronectin were almost completely missing. In brown fat tiss ue and hibernomas the characteristic multivacuolated cells differed fr om the monovacuolated white fat cells by the additional content of hep aran sulfate proteoglycan and fibronectin and the more intensive stain ing for the other components tested. In contrast, multi-/monovacuolate d cells in lipoblastomas exhibited no characteristic immunohistochemic al feature because they reacted irregularly and only faintly for colla gen IV, laminin, and heparan sulfate proteoglycan. Spindle cell areas in benign lipomatous tumors displayed more fibronectin than laminin an d heparan sulfate proteoglycan indicating a ''preadipose'' fibroblast- like cellular differentiation. In liposarcomas, only well-differentiat ed lipoma-like neoplasms revealed a basement membrane pattern resembli ng that of white fat tissue. Otherwise, in nonlipoma-like liposarcomas , a marked decrease particularly of collagen TV staining was evident. Poorly differentiated liposarcomas mostly failed to express any of the basement membrane components, but showed a relative increase of fibro nectin. Our results provide evidence that the staining pattern of base ment membrane components parallels the histogenetic derivation of beni gn lipomatous tumors from either brown or white adipose tissue and, ad ditionally, may reflect such a derivation in liposarcomas.