TYPE-I AND TYPE-III COLLAGENS IN CUTANEOUS MUCINOSIS

Cutaneous mucinoses are a heterogeneous group of diseases characterize d by the focal or diffuse dermal deposition of glycosaminoglycans. The histopathologic examination of many cutaneous mucinoses reveals that the collagen fibers are fragmented. We wanted to characterize the type I (COL1) and type III (COL3) collagen distribution in skin biopsy spe cimens of patients with cutaneous mucinosis. The diagnosis of mucinosi s was based on a modification of the classification by Rongioletti and Rebora: four patients had familial papulonodular mucinosis: four had papular mucinosis, one of which was associated with myxedema and one h ad scleromyxedema; and one had focal mucinosis. We performed anti-type I and type III collagens immunolabeling on frozen sections. Immunoflu orescence for COL1 was increased in the superficial dermis of 2/4 fami lial papulonodular mucinosis, in 5/5 of papular mucinosis, and in scle romyxedema and focal mucinosis cases. The mid-dermis showed intense st aining for COL1 at the periphery of collagen bundles and, in three cas es of familial papulonodular mucinosis and two cases of papular mucino sis, a lacy appearance. The superficial dermis of familial papulonodul ar mucinosis specimens and of papular mucinosis + myxedema, scleromyxe dema, and focal mucinosis specimens had decreased COL3 staining. The m id-dermis showed a more prominent fibrillar staining at the periphery of the collagen bundles, and two cases of papular mucinosis showed int ense labeling for COL3. Both COL1 and COL3 distributions are altered i n cutaneous mucinosis. An intense labeling with COL1 is predominantly found in the superficial layer of cutaneous mucinosis. Cases of FTP re vealed decreased COL3 reactivity at the superficial layer.