A case of a heavily pigmented orbital melanocytoma

Hitoshi Tsugu, Kazuki Nabeshima, Shinji Matsumoto, Tadahiro Omura, Tatsumi Yahiro, Shinya Oshiro, Fuminari Komatsu, Hiroshi Abe, Takeo Fukushima, Toru Inoue, Koichi Takano

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8 Citations (Scopus)


We present an extremely rare case of an orbital melanocytoma that occurred in a 51-year-old man. The patient suffered from diplopia and mild exophthalmos of the right eye for 2 months. Brain magnetic resonance imaging showed a well-demarcated round mass 3.5 cm in diameter in the right orbit. We performed total resection of this tumor. Histological findings revealed a proliferation of large polygonal cells with fine pigment granules in the cytoplasm and prominent nucleoli. Although these tumor cells revealed immunohistochemical reactivity in HMB-1, there was no S-100 or Melan A antibody reactivity. Also, there were no malignant findings of nuclear polymorphism, mitoses, or necrosis. The brown pigments were confirmed to be melanin by bleaching and the Fontana-Masson silver stain method. The MIB-1 labeling index was less than 1%. This tumor also consisted of 50% melanophages, which revealed immunohistochemical reactivity in CD68, CD163, and in (1-AT antibodies. These histological findings led us to diagnose an orbital melanocytoma with partial tumor regression.

Original languageEnglish
Pages (from-to)25-29
Number of pages5
JournalBrain tumor pathology
Issue number1
Publication statusPublished - 04-2009
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Oncology
  • Clinical Neurology
  • Cancer Research


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