The clinicopathologic observation, c-KIT gene mutation and clonal status of gastrointestinal stromal tumor in the sacrum.
BACKGROUND
It is very rare that gastrointestinal stromal tumor (GIST) occurs in the sacrum. Only one case of GIST occuring in the sacral region, with intracranial metastasis, has been reported in the literature. Moreover, only few cases have been published in literature about its clonal origin.


METHODS
In this report, we present a rare case of GIST occuring in the sacrum and describe its clinicopathologic features, c-KIT gene mutation and clonal status. Microscopically, the lesion was composed of spindle cells arranged in cords, knitted and whirlpool patterns. Trabecula of bone were found in the lesion. The cytoplasm of tumor cells were abundant, and the nuclei were fusiform. Mitotic figures were rare. Immunohistochemically, the tumor cells showed positive reactivity for CD117 and CD34. On mutation analysis, a c-KIT gene mutation was found in exon 11. The result of clonal analysis demonstrated that the GIST was monoclonal.


CONCLUSIONS
In summary, we showed that tumor material, phenotypically identical with GISTs was found in the sacrum. It is difficult to differentiate GISTs from other spindle cell tumors, hence the need for immunohistochemistry, the examination of c-KIT gene amplification and sequencing.
Gong
Li
L
Department of Pathology, Tangdu Hospital, the Fourth Military Medical University, Xi'an 710038, Shaanxi Province, PR China. gongli1976@126.com
Li
Yan-Hong
YH
Zhao
Hua-Dong
HD
Zhao
Jian-Ye
JY
Zhang
Wei
W
D018952:Antigens, CD34 / Q000378:metabolism; D001483:Base Sequence; D001859:Bone Neoplasms / Q000175:diagnosis / Q000235:genetics* / Q000473:pathology*; D005091:Exons / Q000235:genetics; D005260:Female; D046152:Gastrointestinal Stromal Tumors / Q000175:diagnosis / Q000235:genetics* / Q000473:pathology*; D006801:Humans; D008875:Middle Aged; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics*; D019009:Proto-Oncogene Proteins c-kit / Q000235:genetics* / Q000378:metabolism; D012447:Sacrum / Q000378:metabolism / Q000473:pathology*
D018952:Antigens, CD34; D019009:Proto-Oncogene Proteins c-kit