Immunophenotype analysis ofmalignant histiocytosis oftheintestine

techniques. Inparaffin sections tumourcells in all caseswereshowntocontain a--antitrypsin andtoexpresstheleucocyte common antigen. Four ofthefive casesofmalignant histiocytosis oftheintestine andthecaseofhistiocytic lymphoma expressed theepithelial membrane antigen. Cryostat sections infour casesofmalignant histiocytosis oftheintestine showed that mosttumourcells reacted withanti-T cell monoclonal antibodies. Only aminority expressed a typical monocytemacrophage phenotype. Malignant histiocytosis oftheintestine hasonly recently beenrecognised'- 3andisbeing increasingly diagnosed with theaidofimmunohistochemical techniques, especially inassociation withcoeliac disease.4 Asfresh tissue forimmunological studies israrely available diagnosis ofthis disease hasrelied onthe recognition ofvariable morphological patterns and theconfirmation ofthepresence ofa-I-anti-trypsin (alAT),a markerofhistiocytic tumourcells in paraffin sections.5 Thehistogenesis ofmalignant histiocytosis oftheintestine hasbeensparsely documented. A study oftheimmunological, immunohistochemical, andcytochemical properties ofthe cells ofmalignant histiocytosis oftheintestine3 included onlythree cases, withalimited frozen section immunohistochemical analysis ononly onecase. A recent study ofhistiocytic lymphoma showed phenotypic heterogeneity within truehistiocytic malignancies, withresults insomecases, suggesting differentiation ofthemalignant histiocytes towards specialised subsets.6 Thislast study didnotinclude cases ofmalignant histiocytosis oftheintestine. The pronounced morphological heterogeneity within the neoplastic cells ofcasesofmalignant histiocytosis of theintestine suggests thata similar immunophenotypic variation maybepresent. Inourstudy weusedimmunoperoxidase techniques, andalarge number ofantisera (both monoclonal andpolyclonal) weretested oncryostat andformalin fixed paraffin embeddedsections fromcasesof malignant histiocytosis oftheintestine. Theresults werecompared withthose ofacaseoftruehistiocytic lym