title: Aneurysmal fibrous histiocytoma showing transition from factor XIIIa-positive to -negative.
abstract: A 39-year-old woman visited us because of a subcutaneous induration on her forehead of 7 months' duration. The tumor was tender, firm, and colored blue-black. Microscopically, the tumor was composed of fibroblastic and histiocytic cells showing no atypicality. In some part intra- or extracellular haemosiderin was diffusely seen. There were some blood-filled spaces of varying size without endothelial lining. From these findings, this case was diagnosed as aneurysmal fibrous histiocytoma (AFH), a variant form of dermatofibroma. Immunohistochemical analysis showed that factor XIIIa-positive histiocytic cells were distributed in the area without haemosiderin, but such cells were absent in the area with its deposition. Furthermore, the cells near the blood-filled space showed transition from factor XIIIa-positive to -negative, suggesting that the stromal instability induced by the attenuation of factor XIII may lead the formation of the blood-filled spaces in AFH.
authors.affiliation: Department of Dermatology, Course of Molecular Medicine, Graduate School of Medicine, Osaka University, Japan.
authors.forename: Shigeki
authors.initials: S
authors.lastname: Inui
authors.forename: Satoshi
authors.initials: S
authors.lastname: Itami
authors.forename: Kunihiko
authors.initials: K
authors.lastname: Yoshikawa
mesh_terms: D000328:Adult; D001707:Biopsy, Needle; D003937:Diagnosis, Differential; D026122:Factor XIIIa / Q000032:analysis*; D005260:Female; D005546:Forehead; D006391:Hemangioma / Q000175:diagnosis; D018219:Histiocytoma, Benign Fibrous / Q000175:diagnosis / Q000473:pathology* / Q000601:surgery*; D006801:Humans; D007150:Immunohistochemistry; D008545:Melanoma / Q000175:diagnosis; D012878:Skin Neoplasms / Q000175:diagnosis / Q000473:pathology* / Q000601:surgery*
chemical_list: D026122:Factor XIIIa