title: Benign fibrous histiocytoma with indeterminate cells and eosinophils: collision, differentiation, or involution?
abstract: This report describes the clinicopathologic, immunohistochemical, and ultrastructural features of a benign fibrous histiocytoma of 3 years' duration situated on the posterior right arm of a 17-year-old woman. To our knowledge, this is the first published description of an association between the histologic features of benign fibrous histiocytoma with proliferating dermal dendrocytes and solid clusters of indeterminate cells and inflammatory infiltrate containing numerous eosinophils. Cell type identification was confirmed by immunohistochemical demonstration of positivity of indeterminate cells for CD1a and S-100 protein, by absence of Birbeck granules in electron microscopy study, and by positivity of fibroblast-like cells for factor XIIIa and negativity for CD34. Mitosis or cytologically atypical cells were absent. The MIB1-measured proliferative index of the tumor cells was less than 5% in spindle cells and approximately 15% in indeterminate cells. Possible pathogenic pathways are discussed that could account for divergent differentiation or a combination of neoplasms of different lineages.
authors.affiliation: Department of Pathology, Infanta Margarita Hospital, Cabra, Córdoba, Spain.
authors.forename: Eduardo
authors.initials: E
authors.lastname: Solís
authors.forename: Amalia
authors.initials: A
authors.lastname: Moreno
authors.forename: Beatriz
authors.initials: B
authors.lastname: Rodríguez-Enríquez
authors.forename: Jesús S
authors.initials: JS
authors.lastname: Sánchez-Vizcaíno
authors.forename: Vicente
authors.initials: V
authors.lastname: Haro
authors.forename: Mariano
authors.initials: M
authors.lastname: Aguilar
authors.forename: Francisco
authors.initials: F
authors.lastname: O'Valle
authors.forename: Raimundo G
authors.initials: RG
authors.lastname: del Moral
mesh_terms: D000293:Adolescent; D018949:Antigens, CD1 / Q000032:analysis; D014408:Biomarkers, Tumor / Q000032:analysis; D002467:Cell Nucleus / Q000648:ultrastructure; D003593:Cytoplasm / Q000648:ultrastructure; D003713:Dendritic Cells / Q000473:pathology; D020405:Dermis / Q000473:pathology; D003937:Diagnosis, Differential; D004804:Eosinophils / Q000473:pathology*; D026122:Factor XIIIa / Q000032:analysis; D005260:Female; D018219:Histiocytoma, Benign Fibrous / Q000737:chemistry / Q000473:pathology* / Q000601:surgery; D006801:Humans; D007299:Insect Bites and Stings / Q000175:diagnosis; D016609:Neoplasms, Second Primary / Q000175:diagnosis*; D019310:Pseudolymphoma / Q000175:diagnosis; D009418:S100 Proteins / Q000032:analysis; D012878:Skin Neoplasms / Q000737:chemistry / Q000473:pathology* / Q000601:surgery
chemical_list: D018949:Antigens, CD1; D014408:Biomarkers, Tumor; C419393:CD1a antigen; D009418:S100 Proteins; D026122:Factor XIIIa