title: Perivascular epithelioid cell tumor (PEComa) of the pancreas: immunoelectron microscopy and review of the literature.
abstract: A perivascular epithelioid tumor (PEComa) is a rare tumor probably arising from the perivascular epithelioid cells. Only three cases of pancreatic PEComa have been reported in the English-language literature. The present report describes an extremely rare case of pancreatic PEComa. A 47-year-old Japanese woman complained of lower abdominal pain and a well-demarcated solid tumor was found in the pancreatic head. There was no history of tuberous sclerosis complexes. Pylorus-preserving pancreaticoduodenectomy was thus performed. There was a well-demarcated, solid tumor measuring 17 mm in the pancreatic head. The tumor was composed of a diffuse proliferation of epithelioid tumor cells with many blood vessels but no adipose tissue. The tumor cells expressed HMB45 and alpha-smooth muscle actin. Ultrastructurally, the tumor cells possessed many membrane-bound granules that were positive for HMB45 on immunoelectron microscopy. The results of immunoelectron microscopy show that some PEComas possess not only typical melanosomes or premelanosomes but also aberrant melanosomes.
authors.affiliation: Department of Pathology, Tokai University School of Medicine, Kanagawa 259-1193, Japan. khira@is.icc.utokai.ac.jp
authors.forename: Kenichi
authors.initials: K
authors.lastname: Hirabayashi
authors.forename: Naoya
authors.initials: N
authors.lastname: Nakamura
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kajiwara
authors.forename: Sadaaki
authors.initials: S
authors.lastname: Hori
authors.forename: Yoshiaki
authors.initials: Y
authors.lastname: Kawaguchi
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Yamashita
authors.forename: Shoichi
authors.initials: S
authors.lastname: Dowaki
authors.forename: Toshihide
authors.initials: T
authors.lastname: Imaizumi
authors.forename: Robert Y
authors.initials: RY
authors.lastname: Osamura
mesh_terms: D000199:Actins / Q000378:metabolism; D000951:Antigens, Neoplasm / Q000378:metabolism; D014408:Biomarkers, Tumor / Q000378:metabolism; D015622:Epithelioid Cells / Q000378:metabolism / Q000648:ultrastructure*; D005260:Female; D006801:Humans; D007150:Immunohistochemistry / Q000379:methods; D058950:Melanoma-Specific Antigens; D020460:Melanosomes / Q000648:ultrastructure; D008875:Middle Aged; D009363:Neoplasm Proteins / Q000378:metabolism; D010190:Pancreatic Neoplasms / Q000378:metabolism / Q000601:surgery / Q000648:ultrastructure*; D016577:Pancreaticoduodenectomy; D054973:Perivascular Epithelioid Cell Neoplasms / Q000378:metabolism / Q000601:surgery / Q000648:ultrastructure*; D016896:Treatment Outcome
chemical_list: C541116:ACTA2 protein, human; D000199:Actins; D000951:Antigens, Neoplasm; D014408:Biomarkers, Tumor; D058950:Melanoma-Specific Antigens; D009363:Neoplasm Proteins