Collagenous spherulosis in chondroid syringomas.

We report a case of collagenous spherulosis (CS) incidentally found in a chondroid syringoma of the facial skin. The lesion was studied by routine light microscopy, special stains, immunohistochemical methods, x-ray spectrophotometry, and electron microscopy. Light microscopy revealed solitary and confluent eosinophilic globules with radiating fibrillary structures within and around the lumina of the tubuloglandular components of chondroid syringoma. The fibrillary structures stained strongly for collagen and reticulin and less intensely for acidic mucopolysaccharides. Immunohistochemically, the globules were focally positive only for collagen type IV. Electron microscopy revealed radiating collagen fibers surrounded by basal lamina-like material. No inorganic crystals were identified by x-ray spectrophotometry. We conclude that (a) CS is not specific to breast but also occurs in chondroid syringomas; (b) the term collagenous spherulosis is appropriate because collagen fibers were demonstrated histochemically and ultrastructurally in the spherules; (c) CS appears to be associated with tubular epithelial structures; (d) there was no immunohistochemical evidence of myoepithelial differentiation. The etiology and significance of CS remain obscure.