The fasciitis-panniculitis syndromes: histomorphometric assessment of the inflammatory and sclerosing processes affecting the subcutaneous and fascial tissues.

Abstract

The fasciitis-panniculitis syndromes include several disorders characterized by skin induration due to fibrotic thickening of the septa of the subcutis and muscular fascia associated with chronic inflammation. Representative of the idiopathic form, eosinophilic fasciitis, is the prototype of the fasciitis-panniculitis syndromes. Secondary forms of the syndromes are causally related to a variety of diseases, such as infections, circulatory disorders, physical injuries and neoplasms. Histological sections of 10 idiopathic and 20 secondary cases of the fasciitis-panniculitis syndromes were assessed by means of computer-assisted image analysis. The percent of fibrous tissue, referred to as "extent of fibrosis", and the number of lymphocytes, macrophages, eosinophils, plasma cells, and mast cells within the subcutaneous-fascial complex were assessed. The "extent of fibrosis" varied from 1% to 2% in the control cases and from 4% to 98% in the index cases. The number of inflammatory cells per high power field varied from 0 to 33 in the control cases and from 9 to 323 in the index cases. There is a direct and positive correlation between the "extent of fibrosis" and the number of inflammatory cells. The "extent of fibrosis" and intensity of the inflammatory infiltration do not correlate with the nature of the underlying diseases, the patients'demographic data, the anatomic location of the subcutaneous induration or the duration of the lesion. It is suggested that the fasciitis-panniculitis syndromes are the morphological expression of a chronic, relapsing, inflammatory-sclerosing reaction pattern that is essentially identical in the idiopathic and the secondary forms of the disorder.