A case of a heavily pigmented orbital melanocytoma.
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.
Tsugu
Hitoshi
H
Department of Neurosurgery, Fukuoka University Faculty of Medicine, 45-1-7 Nanakuma, Jonan-ku, Fukuoka 814-0180, Japan. h-tsugu@fukuoka-u.ac.jp
Nabeshima
Kazuki
K
Matsumoto
Shinji
S
Omura
Tadahiro
T
Yahiro
Tatsumi
T
Oshiro
Shinya
S
Komatsu
Fuminari
F
Abe
Hiroshi
H
Fukushima
Takeo
T
Inoue
Toru
T
Takano
Koichi
K
D001808:Blood Vessels / Q000473:pathology; D002466:Cell Nucleolus / Q000473:pathology; D004396:Coloring Agents; D003593:Cytoplasm / Q000473:pathology; D006801:Humans; D007150:Immunohistochemistry; D008279:Magnetic Resonance Imaging; D008297:Male; D008543:Melanins / Q000378:metabolism; D020460:Melanosomes / Q000473:pathology; D008875:Middle Aged; D019635:Neurosurgical Procedures; D009506:Nevus / Q000473:pathology* / Q000601:surgery; D009918:Orbital Neoplasms / Q000473:pathology* / Q000601:surgery; D016622:Silver Staining; D016707:Tissue Fixation
D004396:Coloring Agents; D008543:Melanins