title: Silica reaction simulating fibrous histiocytoma.
abstract: An unusual foreign body reaction to silica (quartz), resembling fibrous histiocytoma, is described in 7 patients (age range 22 to 71 years). These lesions occurred in the inguinal region (4 cases) or the abdominal wall (3 cases), and in 5 instances were associated with a history of injection at the same site 10 to 41 years previously. Most commonly the injection consisted of the administration of a sclerosing agent for the repair of a hernia. Microscopically these lesions contained broad sheets of histiocytes separated by bands or concentrically lamellated nodules of collagen. Intra- and extra-cellular birefringent crystals, identified by x-ray diffraction as silica (quartz), were present in all cases and served to distinguish this process from a true neoplasm. Although the injection therapy for hernia is now obsolete, it was formerly practiced in the United States with a variety of sclerosing agents including silica (quartz). Since these lesions are often confused with a benign or malignant fibrous histiocytoma it is recommended that fibro-histiocytic lesions associated with a previous hernia or injection at the same site be examined for the presence of silica.
mesh_terms: D000328:Adult; D000368:Aged; D003937:Diagnosis, Differential; D005260:Female; D006547:Hernia / Q000188:drug therapy; D018219:Histiocytoma, Benign Fibrous / Q000175:diagnosis*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011819:Rabies Vaccines / Q000009:adverse effects; D012822:Silicon Dioxide / Q000009:adverse effects*; D012829:Silicosis / Q000175:diagnosis* / Q000209:etiology / Q000473:pathology; D012983:Soft Tissue Neoplasms / Q000175:diagnosis*
chemical_list: D011819:Rabies Vaccines; D012822:Silicon Dioxide