THE BASEMENT-MEMBRANES IN SARCOMATOID CARCINOMAS - AN IMMUNOHISTOCHEMICAL STUDY

Aims: Eight sarcomatoid carcinomas from various anatomical locations w ere investigated by immunohistochemical staining to laminin, type IV c ollagen and heparan sulfate proteoglycan, to study the characteristics of basement membranes at the interface between carcinomatous and sarc omatous tissues. Methods: Paraffin wax embedded tissue sections from r epresentative tumor samples have been stained with specific antibodies , using the peroxidase-antiperoxidase technique. Results: In all cases several interruptions or discontinuities of the basement membrane sta ining pattern were seen. In 4 cases, larger defects or complete loss o f staining was also noted. At these places, the boundaries between car cinomatous and sarcomatous tissue were often blurred. Conclusions: Dis ruption and loss of basement membranes at interface between carcinomat ous and sarcomatous tissues is a frequent finding in sarcomatoid carci nomas. These changes could be consistent with an epithelial origin of the sarcomatous component in these tumors by means of an epithelial-me senchymal conversion mechanism.