Soft tissue tumours

This section highlights some of the topical areas and papers published in 1988-89.It is by no means comprehensive but the intention is that it gives a brief overview to those who do not have a specialized interest in this area, and there is emphasis on topics which are of diagnostic value. SOFT TISSUE TUMOURSThe aim of this brief review is to summarize several of the more important and topical diagnostic developments that have emerged in the field of soft tissue neoplasms over the past 18 months or so. NEW ENTITIESPlexiform fibrohistiocytic tumour was described by Enzinger and Zhang in November 1988' and probably represents one of the last of the 25 or so types of tumour which Enzinger has been involved in delineating, as this giant of soft tissue pathology has now retired from the A.F.I.P. Sixty-five cases of this distinctive cutaneous/subcutaneous lesion were presented, almost 90 per cent of which arose in the first three decades of life with a predominance in females.Much the commonest site was the upper limb.Original diagnoses ranged from giant cell tumour through fibromatosis to MFH.Most cases presented as a slowly-growing, ill-defined nodule, less than 3 cm in diameter.Cardinal histological features were the presence of variable proportions of 'fibrohistiocytic' nodules and irregularly ramifying, rather cellular fibroblastic bundles, morphologically resembling a desmoid tumour.The 'fibrohistiocytic' nodules consisted of well-circumscribed aggregates of plump, rather eosinophilic histiocyte-like cells, scattered osteoclast-like giant cells and fibroblasts, admixed peripherally with chronic inflammatory cells.The extent to which the proportions of these two components varied was particularly striking.The principal evidence provided to support 'fibrohistiocytic' classification was positivity for alpha-1 -antitrypsin and alpha-1 -antichymotrypsin in less than a third of cases.The probable non-specificity of this result was, however, mentioned and personal experience suggests that the nodules described above do not stain with monoclonal markers of macrophage/ monocyte origin, as is the case with most so-called fibrohistiocytic tumours.