Epithelioid malignant peripheral nerve sheath tumor. Report of a case with inflammatory infiltration.
The epithelioid malignant peripheral nerve sheath tumor (EMPNST) is a rare sarcoma originating from the supportive non-neuronal components of peripheral nerves. Our patient was a 75-year-old Japanese man who presented with complaints about pain and a mass in the left thigh. Characteristic histopathological features were large epithelioid-like cells closely resembling a malignant melanoma or another type of soft tissue tumor. Notable infiltration of neutrophils in the tumor was seen. Immunohistochemically, the tumor cells proved positive for S-100, NSE, GFAP, MBP, chromogranin A and synaptophysin, and negative for CEA, keratin, HMB-45, G-CSF, and GM-CSF. Tumor-related inflammatory infiltration may be caused by an autonomous production of some cytokines. However, these tumor cells were negative for G-CSF and GM-CSF so that the mechanism triggering inflammatory infiltration is unclear. Electron microscopy revealed the presence of an extracellular basal lamina, intermediate cell junctions, and numerous dense-cored granules in the cytoplasm. These findings suggested a schwannian derivation, consistent with the diagnosis of EMPNST. There have been reports on S-100 positivity and HMB-45 negativity of this tumor type, but to the best of our knowledge, this is the first description of an EMPNST positive for MBP, chromogranin A, and synaptophisin. Where unequivocal features are lacking, these markers might be useful for differential diagnosis.
Onco-Pathology, Department of Pathology and Host-Defense, Faculty of Medicine, Kagawa University, 1750-1 Ikenobe, Miki-cho, Kita-gun, Kagawa 761-0793, Japan.
Yoko
Y
Matsuda
Kousuke
K
Saoo
Kyoko
K
Hosokawa
Keiko
K
Yamakawa
Masanao
M
Yokohira
Yu
Y
Zeng
Hijiri
H
Takeuchi
Junko
J
Iwai
Takatoshi
T
Shirai
Kaoru
K
Obika
Katsumi
K
Imaida
D000368:Aged; D014408:Biomarkers, Tumor / Q000032:analysis; D003937:Diagnosis, Differential; D015622:Epithelioid Cells / Q000737:chemistry / Q000473:pathology*; D006801:Humans; D007150:Immunohistochemistry; D008175:Lung Neoplasms / Q000175:diagnosis / Q000556:secondary; D008279:Magnetic Resonance Imaging; D008297:Male; D008545:Melanoma / Q000175:diagnosis; D018317:Nerve Sheath Neoplasms / Q000737:chemistry / Q000556:secondary* / Q000601:surgery; D009504:Neutrophils / Q000473:pathology; D012983:Soft Tissue Neoplasms / Q000737:chemistry / Q000473:pathology* / Q000601:surgery; D013848:Thigh / Q000473:pathology
D014408:Biomarkers, Tumor