title: Melanotic schwannoma of the choroid. Immunohistochemistry and electron microscopic observations.
abstract: OBJECTIVE
  The purpose of this article is to describe what is probably the first reported case of a melanotic schwannoma of the choroid and to discuss the clinical and histopathologic features that serve to differentiate this rare intraocular tumor from a malignant melanoma of the choroid.
  
  
  METHODS
  A 21-year-old woman underwent enucleation of the right eye for a slowly enlarging pigmented choroidal mass that was associated with ipsilateral blindness. The tumor was studied by light microscopy, immunohistochemistry, and electron microscopy.
  
  
  RESULTS
  The tumor was composed of fascicles and whorls of pigmented and nonpigmented plump spindle cells that had light microscopic features of a schwannoma. The tumor cells showed immunoreactivity to S-100 protein and HMB-45. Electron microscopy showed cytoplasmic processes surrounded by a continuous basement membrane and abundant extracellular collagen. The pigmented spindle-shaped cells contained melanosomes in different stages of melanogenesis. The findings were compatible with a melanotic schwannoma.
  
  
  CONCLUSIONS
  Melanotic schwannoma has been reported in soft tissues, peripheral nerves, and in the orbit. To the authors' knowledge, this is the first report of a melanotic schwannoma of the choroid. This extremely rare pigmented choroidal tumor may be very difficult to differentiate clinically from choroidal melanoma.
authors.affiliation: Ocular Oncology Service, Wills Eye Hospital, Thomas Jefferson University, Philadelphia, PA 19107.
authors.forename: J A
authors.initials: JA
authors.lastname: Shields
authors.forename: R L
authors.initials: RL
authors.lastname: Font
authors.forename: R C
authors.initials: RC
authors.lastname: Eagle
authors.forename: C L
authors.initials: CL
authors.lastname: Shields
authors.forename: J D
authors.initials: JD
authors.lastname: Gass
mesh_terms: D000328:Adult; D002830:Choroid Neoplasms / Q000378:metabolism / Q000648:ultrastructure*; D003598:Cytoskeletal Proteins / Q000032:analysis; D015353:Eye Enucleation; D005260:Female; D005654:Fundus Oculi; D006801:Humans; D007124:Immunoenzyme Techniques; D009363:Neoplasm Proteins / Q000032:analysis; D009442:Neurilemmoma / Q000378:metabolism / Q000648:ultrastructure*; D009418:S100 Proteins / Q000032:analysis
chemical_list: D003598:Cytoskeletal Proteins; D009363:Neoplasm Proteins; D009418:S100 Proteins