Clear cell tumor of the lung. Immunohistochemical and ultrastructural evidence of melanogenesis

Am J Surg Pathol. 1991 Jul;15(7):644-53. doi: 10.1097/00000478-199107000-00005.


Clear cell tumors of the lung (CCTL) are rare neoplasms of uncertain differentiation. A previous study of eight CCTL demonstrated a lack of epithelial features, but their exact nature remained unknown. In the current study of nine CCTL, immunohistochemistry using preliminary enzymatic digestion showed strong reactivity with the antimelanocytic markers HMB-45 (seven cases) and HMB-50 (six cases) and focal positivity for S-100 (nine cases), neuron-specific enolase (three cases), synaptophysin (one case), and Leu-7 (one case). Staining for cytokeratin, epithelial membrane antigen, chromogranin, and glial fibrillary acid protein was uniformly negative. Frozen-section immunoreactivity for vimentin and the antimelanocytic monoclonal preparation NKI/BETEB was noted in the one CCTL for which snap-frozen tissue was available. Ultrastructural examination of three glutaraldehyde-fixed CCTL showed rare neoplastic cells containing the full spectrum of melanosomes in two, one of which also contained neurosecretory-type granules. Aberrant melanosomal forms were identified in the third case. Melanosomes were not identified in the remaining five CCTL studied from formalin- or paraffin-retrieved material. The findings indicate that CCTL exhibits melanocytic differentiation. This feature may be of considerable value in distinguishing CCTL from other clear cell neoplasms.

MeSH terms

  • Antibodies, Monoclonal / metabolism
  • Antigens, Differentiation / metabolism
  • CD57 Antigens
  • Humans
  • Immunohistochemistry
  • Lung Neoplasms / metabolism
  • Lung Neoplasms / pathology*
  • Lung Neoplasms / ultrastructure
  • Melanocytes / metabolism
  • Melanocytes / pathology*
  • Melanocytes / ultrastructure
  • Membrane Proteins / metabolism
  • Microscopy, Electron
  • Phosphopyruvate Hydratase / metabolism
  • S100 Proteins / metabolism
  • Synaptophysin


  • Antibodies, Monoclonal
  • Antigens, Differentiation
  • CD57 Antigens
  • Membrane Proteins
  • S100 Proteins
  • Synaptophysin
  • Phosphopyruvate Hydratase