INFLAMMATORY PSEUDOTUMOR OF SOFT-TISSUES - A CLINICOPATHOLOGICAL AND IMMUNOHISTOCHEMICAL ANALYSIS OF 18 CASES

Pseudosarcomatous proliferations of myofibroblasts, fibroblasts and in flammatory cells have been reported in a wide variety of sites and are most commonly termed inflammatory pseudotumours. Despite increasing r ecognition, the occurrence of inflammatory pseudotumour in somatic sof t tissue is poorly documented, such that these lesions are commonly mi staken for a variety of benign and malignant neoplasms. This report do cuments our experience of 18 cases of soft tissue inflammatory pseudot umour. All arose in adults (median age 54.5 years: range 28-83 years) and showed no sex predilection. Anatomical location was varied but the head and neck region and abdominal cavity were most common. They disp layed a spectrum of histological appearances but all were characterize d, to a greater or lesser extent, by an admixture of myofibroblasts an d fibroblasts, most commonly arranged in short interwoven fascicles, t ogether with a polymorphic inflammatory cell component, consisting pri ncipally of lymphocytes and plasma cells. In some cases xanthoma cells were prominent. Simple surgical excision appeared to be curative. The importance of recognizing the presence of a wide clinicopathological spectrum is emphasized and the differential diagnosis, especially from fibrohistiocytic neoplasms or Hodgkin's disease, is discussed.