title: Metastatic balloon cell melanoma: a case report.
abstract: BACKGROUND
  The protean morphology of malignant melanoma is diagnostically challenging. Balloon cell melanoma is a histologic variant composed predominantly or entirely of large cells with abundant, vacuolated cytoplasm. It shares the cytologic features of the other subcategories of malignant melanoma, such as discohesion, nuclear pleomorphism and intranuclear cytoplasmic pseudoinclusions, but generally lacks melanin pigment and, as the name would suggest, is characterized by the presence of numerous cytoplasmic vacuoles.
  
  
  METHODS
  A 55-year-old man presented with an enlarged right cervical lymph node. Clinically and radiographically this mass was considered to be metastatic; however, the patient had no known primary neoplasm. Fine needle aspiration biopsy (FNAB) and cytologic examination showed numerous discohesive, variably sized, malignant cells with abundant, vacuolated cytoplasm and pleomorphic nuclei with irregular nuclear contours, macronucleoli and frequent intranuclear cytoplasmic pseudoinclusions. Pigment was not identified. These features, along with strong immunohistochemical positivity for S-100, HMB-45 and Melan-A, suggested the diagnosis of balloon cell melanoma. A right parotidectomy and lymph node dissection were performed, and histologic tissue evaluation confirmed the diagnosis.
  
  
  CONCLUSIONS
  This case of lymph node balloon cell melanoma metastasis was diagnosed by FNAB.
authors.affiliation: Division of Cytopathology, University of California, San Francisco 94115, USA. flbaehn@itsa.ucsf.edu
authors.forename: Frederick L
authors.initials: FL
authors.lastname: Baehner
authors.forename: Brenda
authors.initials: B
authors.lastname: Ng
authors.forename: Daniel
authors.initials: D
authors.lastname: Sudilovsky
mesh_terms: D000951:Antigens, Neoplasm; D014408:Biomarkers, Tumor / Q000032:analysis; D001707:Biopsy, Needle; D002467:Cell Nucleus / Q000473:pathology; D003593:Cytoplasm / Q000473:pathology; D003937:Diagnosis, Differential; D006801:Humans; D045586:Intranuclear Inclusion Bodies / Q000473:pathology; D008198:Lymph Nodes / Q000473:pathology*; D008207:Lymphatic Metastasis; D058965:MART-1 Antigen; D008297:Male; D008545:Melanoma / Q000145:classification / Q000556:secondary*; D058950:Melanoma-Specific Antigens; D008875:Middle Aged; D009363:Neoplasm Proteins / Q000032:analysis; D009382:Neoplasms, Unknown Primary / Q000473:pathology*; D009418:S100 Proteins / Q000032:analysis
chemical_list: D000951:Antigens, Neoplasm; D014408:Biomarkers, Tumor; D058965:MART-1 Antigen; C548667:MLANA protein, human; D058950:Melanoma-Specific Antigens; D009363:Neoplasm Proteins; D009418:S100 Proteins