Primary pulmonary malignant peripheral nerve sheath tumor: a case report.
BACKGROUND
Although the histologic features of malignant peripheral nerve sheath tumor (MPNST) have been described, the cytologic features of primary pulmonary MPNST have not been reported in the literature.


METHODS
We report a case of primary pulmonary MPNST in a 78-year-old man. Follow-up computed tomography of colon cancer, renal cancer, penile cancer and gingival cancer revealed a nodular lesion, 12 mm in diameter, in the right upper lobe of the lung. In frozen section, a diagnosis of malignant neoplasm, not otherwise specified, was rendered for the imprinting specimen and histologic specimen. Imprinting specimens were composed of small cellular aggregates and discohesive neoplastic cells with obvious malignant features. Histologically, spindle cells with pleomorphic nuclei arranged infascicular patterns and multinucleated tumor giant cells were also observed. More than 25 mitotic figures were observed per 10 high-power fields. Tumor cells were positive only for vimentin and S-100, and the Ki-67 labeling index was 10%. Clinical and imaging investigation failed to identify an alternative primary site. We histologically diagnosed this case as primary pulmonary MPNST.


CONCLUSIONS
MPNST has a varied cytomorphology with frank nuclear atypia showing no definite differentiation. Multinucleated neoplastic giant cells with immunopositivity for S-100 may permit more accurate diagnosis of MPNST.
Tashiro
Takashi
T
Pathology Division, Hyogo Prefectural Kakogawa Hospital, Hyogo, Japan. kenkako1@gold.ocn.ne.jp
Kawakita
Chisato
C
Takai
Chikako
C
Yoshida
Takahiro
T
Sakiyama
Shoji
S
Kondo
Kazuya
K
Sano
Nobuya
N
D000368:Aged; D002467:Cell Nucleus / Q000473:pathology; D015726:Giant Cells / Q000473:pathology; D006801:Humans; D008175:Lung Neoplasms / Q000473:pathology*; D008297:Male; D018317:Nerve Sheath Neoplasms / Q000473:pathology*; D009418:S100 Proteins / Q000378:metabolism
D009418:S100 Proteins