White opaque substance represents an intracytoplasmic accumulation of lipid droplets: immunohistochemical and immunoelectron microscopic investigation of 26 cases.
OBJECTIVE
White opaque substance (WOS) in gastric neoplasias is a unique finding visualized in magnifying endoscopy (ME) with narrow band imaging (NBI) and it represents intramucosal accumulation of lipid droplets using oil red O staining.


METHODS
Subjects were 26 WOS-positive (13 adenomas and 13 well-differentiated adenocarcinomas) and 27 WOS-negative gastric epithelial neoplasias. We carried out immunohistochemical staining using a monoclonal antibody specific for adipophilin as a marker of lipids. Immunoelectron microscopy was used to evaluate morphology of the lipid droplets.


RESULTS
Adipophilin was detected in 24 of 25 (96.0%) WOS-positive neoplasias, but it was detected in only two of 27 (7.4%) WOS-negative neoplasias. Lipid droplets were only seen in the surface epithelium in 10 of 11 (91.1%) adenomas, whereas the lipid droplets also existed in the cryptal epithelium in seven of 13 (53.8%) adenocarcinomas. Immunoelectron microscopy revealed numerous lipid droplets mainly existing in the subnuclear cytoplasm of the epithelium. The shape of the lipid droplets in adenomas was round and uniform, whereas that in adenocarcinomas was irregular.


CONCLUSIONS
The present study confirmed that the presence of WOS in gastric neoplasias was dependent upon intramucosal accumulation of lipid droplets using anti-adipophilin staining. Intraepithelial distribution and morphology of the lipid droplets differed between adenoma and adenocarcinoma.
Department of Gastroenterology, Oita Red Cross Hospital, Japan. ueo14@athena.ocn.ne.jp
Tetsuya
T
Ueo
Hirotoshi
H
Yonemasu
Naomi
N
Yada
Shinji
S
Yano
Tetsuya
T
Ishida
Masaki
M
Urabe
Ken
K
Takahashi
Hideyasu
H
Nagamatsu
Ryoichi
R
Narita
Kenshi
K
Yao
Tsutomu
T
Daa
Shigeo
S
Yokoyama
D000230:Adenocarcinoma / Q000378:metabolism; D000236:Adenoma / Q000378:metabolism; D000368:Aged; D000369:Aged, 80 and over; D016099:Endoscopy, Gastrointestinal / Q000379:methods*; D004848:Epithelium / Q000378:metabolism; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008055:Lipids / Q000737:chemistry*; D008297:Male; D008565:Membrane Proteins / Q000378:metabolism; D016253:Microscopy, Immunoelectron; D008875:Middle Aged; D062048:Narrow Band Imaging; D000070780:Perilipin-2; D013274:Stomach Neoplasms / Q000378:metabolism*
D008055:Lipids; D008565:Membrane Proteins; C000602982:PLIN2 protein, human; D000070780:Perilipin-2