Immunohistological demonstration of factors XIIIa and XIIIs in reactive and neoplastic fibroblastic and fibro-histiocytic lesions.

Factor XIII sub-units a and s (XIIIa and XIIIb) have been localized previously in fibroblasts of the liver and in other tissues. An immunoperoxidase technique was used to localize these factors in benign and malignant fibroblastic and fibro-histiocytic lesions. Positive staining was present in cells in almost all of the benign and fibro-histiocytic lesions but was reduced in the malignant group. However, the pattern of staining was not sufficiently consistent to justify the use of the factors XIII as diagnostic markers in soft tissue neoplasia.