title: Fibrous histiocytoma of the tarsus: clinical and immunohistochemical observations with a differential diagnosis.
abstract: OBJECTIVE
  To describe the diagnostic clinical findings and immunopathology of a fibrous histiocytoma of the upper eyelid tarsus of a 42-year-old man.
  
  
  METHODS
  Analysis of clinical features and results of histopathologic and immunohistochemical evaluations using antibodies against the biomarkers smooth muscle actin, S100, CD1a, CD3, CD20, CD31, CD34, CD68, CD163, factor XIIIa, adipophilin, androgen receptor, and Ki-67.
  
  
  RESULTS
  The skin moved over a firm lesion that was situated in the tarsus and protruded from the palpebral conjunctiva as a whitish flat-domed noninflamed mass that had caused an irritating corneal epitheliopathy. Histopathologically, there was a storiform or spiral nebular growth pattern, a moderate amount of intercellular collagen, and no nuclear atypia or mitotic activity. The main immunohistochemical findings were CD34 and smooth muscle actin negativity among the tumor cells and a scarcity of CD68/163 histiocytes. Androgen receptors were identified in the tumor cells.
  
  
  CONCLUSIONS
  CD34 histiocytoma of the tarsus is a rare, benign, and separate entity from a CD34 solitary fibrous tumor. Conservative tarsectomy is curative.
authors.affiliation: *David G. Cogan Laboratory of Ophthalmic Pathology, Department of Ophthalmology, Massachusetts Eye and Ear Infirmary, Boston, MA; †Department of Ophthalmology, Harvard Medical School; and ‡Ophthalmic Plastic Surgery Service, Department of Ophthalmology, Massachusetts Eye and Ear Infirmary, Boston, MA.
authors.forename: Frederick A
authors.initials: FA
authors.lastname: Jakobiec
authors.forename: Ruju
authors.initials: R
authors.lastname: Rai
authors.forename: Michael K
authors.initials: MK
authors.lastname: Yoon
mesh_terms: D000328:Adult; D014408:Biomarkers, Tumor / Q000378:metabolism*; D003937:Diagnosis, Differential; D005142:Eyelid Neoplasms / Q000175:diagnosis* / Q000378:metabolism / Q000601:surgery; D018219:Histiocytoma, Benign Fibrous / Q000175:diagnosis* / Q000378:metabolism / Q000601:surgery; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D009363:Neoplasm Proteins / Q000378:metabolism*
chemical_list: D014408:Biomarkers, Tumor; D009363:Neoplasm Proteins