Comparative analysis of histopathological parameters, genome-wide copy number alterations, and variants in genes involved in cell cycle regulation in chordomas of the skull base and sacrum.

Chordomas are rare tumors of the axial skeleton that are refractory to conventional therapy. Few studies have compared the morphological and molecular characteristics of chordomas according to the skull base and sacral locations. Histopathological data and changes revealed by array comparative genomic hybridization (CGH) and next-generation sequencing (NGS) of cell cycle regulation genes were analyzed for 28 skull base (SBCs) and 15 sacral (SC) chordomas. All cases were conventional chordomas. SBCs were significantly more frequent in patients aged <40 years and SCs predominated in patients aged >60 years. Mitotic indices ≥2 mitoses/10 high-power fields were correlated with high degrees of nuclear atypia and Ki67 labeling indices ≥6%. We identified 321 genomic positions, and copy number variation losses were more frequent than gain. Moreover, we report a panel of 85 genetic variants of cell cycle genes and the presence of molecular clusters for chordoma as well in CGH as in NGS. These new data strengthen the view that the chordoma should not be considered as a single molecular entity.

Neuroprotective Effects of Rhodiola Sacra on Transient Global Cerebral Ischemia Through Activating AMPK/Nrf2 Pathway in Rats.

Aims: Rhodiola sacra is a widely used pharmaceutical component with multiple functions, including anti-oxidation and anti-inflammation. However, the exact mechanisms involved in neuroprotection against transient global cerebral ischemia (tGCI) remain to be elucidated. Herein, we aim at closing the gap in understanding on whether rhodiola sacra reduces neuronal death in hippocampal CA1 and at demonstrating how rhodiola sacra offers neuroprotection after tGCI. Results: The results show that rhodiola sacra (2.4 g/kg/d by feeding) pretreatment or/and postreatment significantly alleviated neuronal injury, inhibited glial activation, and improved cognitive function in male rats subjected to tGCI. The neuroprotection of prophylaxis with rhodiola sacra is equivalent to that of therapeutics. The binding mode of adenosine monophosphate-activated protein kinase (AMPK) α2-subunit with rhodiola sacra was predicted by molecular docking. Further, rhodiola sacra upregulates phosphorylated AMPK and promotes nuclear translocation of nuclear factor erythroid 2 related factor 2 (Nrf2). In addition, rhodiola sacra increases heme oxygenase-1 (HO-1) expression and activity and reduces malondialdehyde (MDA) content in CA1 after tGCI. However, the neuroprotection of rhodiola sacra is abolished by Nrf2 knockdown with small interfering RNA (siRNA) after tGCI. Similarly, the inhibition of AMPK with Compound C or siRNA against AMPK α2 aggravates neuronal death after tGCI through decreasing nuclear Nrf2 and the expression and activity of HO-1, and by increasing the release of MDA. Innovation and Conclusion: For the first time, this study demonstrates that as a prophylactic or therapeutic agent rhodiola sacra prevents oxidant stress, protects neurons, and improves cognitive function through activating the AMPK/Nrf2 pathway in tGCI rats. Antioxid. Redox Signal. 36, 567-591.

Sex differences in c-Fos and EGR-1/Zif268 activity maps of rat sacral spinal cord following cystometry-induced micturition.

Storage and voiding of urine from the lower urinary tract (LUT) must be timed precisely to occur in appropriate behavioral contexts. A major part of the CNS circuit that coordinates this activity is found in the lumbosacral spinal cord. Immediate early gene (IEG) activity mapping has been widely used to investigate the lumbosacral LUT-related circuit, but most reports focus on the effects of noxious stimulation in anesthetized female rats. Here we use c-Fos and EGR-1 (Zif268) activity mapping of lumbosacral spinal cord to investigate cystometry-induced micturition in awake female and male rats. In females, after cystometry c-Fos neurons in spinal cord segments L5-S2 were concentrated in the sacral parasympathetic nucleus (SPN), dorsal horn laminae II-IV, and dorsal commissural nucleus (SDCom). Comparisons of cystometry and control groups in male and female revealed sex differences. Activity mapping suggested dorsal horn laminae II-IV was activated in females but showed net inhibition in males. However, inhibition in male rats was not detected by EGR-1 activity mapping, which showed low coexpression with c-Fos. A class of catecholamine neurons in SPN and SDCom neurons were also more strongly activated by micturition in females. In both sexes, most c-Fos neurons were identified as excitatory by their absence of Pax2 expression. In conclusion, IEG mapping in awake male and female rats has extended our understanding of the functional molecular anatomy of the LUT-related circuit in spinal cord. Using this approach, we have identified sex differences that were not detected by previous studies in anesthetized rats.

Ureteral Stone Mimicking Abnormal Sacral Uptake on 99mTc MDP Bone Scintigraphy: The Usefulness of SPECT/CT.

Bone tracer uptake related to ureteral stones has been reported several times before. We present a right ureteral stone mimicking abnormal focal sacral uptake on planar scan in a patient with rectal cancer. This case highlights the necessity of performing SPECT/CT to ascertain the origin of abnormal focal sacral uptake on planar scan, especially in patients with a history of kidney stones.

ADAM10 Is a Potential Novel Prognostic Biomarker for Sacral Chordoma.

The ADAM (A Disintegrin and Metalloprotease) is a zinc-dependent family of transmembrane proteins upregulated in cancers. As the most frequent member, ADAM10's potential prognostic role in chordoma is unknown. OBJECTIVE: We investigated the expression of ADAM10 protein and its prognostic value in sacral chordoma. DESIGN: Clinical information of patients with sacral chordoma diagnosis during a 7-year period and their archived pathology were retrieved. Immunohistochemistry study of the expression of ADAM10 protein in sacral chordoma and control samples was conducted. The ADAM10 expression was correlated with the patients' clinicopathological information and analyzed by statistical methods. RESULTS: The average age of 64 patients was 57.6 years (range, 35-83 years). Follow-up ranged from 12 to 141 months (mean, 72 months). The histological type included 47 classic, 6 chondroid, and 11 dedifferentiated chordomas. The expression level of ADAM10 was significantly correlated with the histological type (χ 2=11.345, P=0.003), metastasis (χ 2=10.149, P=0.001), overall survival (log-rank test: χ 2=8.177, P=0.004) and disease free survival (log-rank test: χ 2=6.805, P=0.009). The average survival time of patients with weak expression of ADAM10 was longer than that of strong expression. CONCLUSION: The expression of ADAM10 protein is related to the histologic type and the prognosis of sacral chordoma.

Targeting the Cohesive Cluster Phenotype in Chordoma via ß1 Integrin Increases Ionizing Radiation Efficacy.

Chordoma is a rare, radiation-resistant, skull-base and spinal tumor with high local recurrence containing mixed cell-adhesion phenotypes. We characterized DNA damage response (DDR) signaling (γH2AX, pKAP1, pATM) and survival response to ionizing radiation (IR) in human chordoma samples (42 resections, 23 patients) to test if blocking cell adhesion sensitizes U-CH1 tumor cells to IR. U-CH1 cells expressed brachyury, YAP, and laminin adhesion receptors (CD49c, CD49f, CD44), and approximately 15% to 20% of U-CH1 cells featured an α6 integrin-dependent (CD49f) cohesive cluster phenotype, which confers therapeutic resistance and aids metastasis. DDR to IR in U-CH1 cells was compared to normal prostate epithelial (PrEC) and tumor cells (DU145). Flow cytometry showed a dose- and time-dependent increase in γH2AX and pKAP1 expression in all cell lines. However, nearly 50% of U-CH1 cells exhibited nonresponsive phenotype to IR (measured by γH2AX and pKAP1) independent of cell cycle status. Immunofluorescence microscopy verified that only 15% of U-CH1 clustered cells were γH2AX or pKAP1 positive (versus 80% of nonclustered cells) 2 hours following 2-Gy IR. Conversely, both tumor cell lines were uniformly defective in pATM response. HYD1, a synthetic ECM ligand, inhibited DDR through an unresolved γH2AX response. ß1 integrin-blocking antibody (AIIB2) decreased cell survival 50% itself and approximately doubled the IR-induced cell kill at all IR doses observed at 2 and 4 weeks posttreatment. These results suggest that a heterogeneity of DDR to IR exists within a chordoma population. Blocking integrin function alone and/or as an adjuvant to IR may eradicate chordomas containing the cohesive cluster phenotype.

Expression of far upstream element-binding protein 1 correlates with c-Myc expression in sacral chordomas and is associated with tumor progression and poor prognosis.

The far upstream element (FUSE)-binding protein 1 (FUBP1), a well-known transcriptional regulator of the proto-oncogene c-Myc, has been demonstrated by previous work to be aberrantly expressed in a variety of tumors and plays a critical role in tumor progression; however, its expression and function in relatively rare and aggressive chordomas remains unclear. In this retrospective study, we reviewed clinicopathologic characteristics of 40 patients diagnosed with sacral chordoma, and analyzed 40 tumor and 20 distant normal tissues obtained from patients during the primary surgical tumor excision. Using immunohistochemistry, we observed an up-regulation in the expression of FUBP1 and c-Myc in sacral chordomas compared with the normal tissues (P = 0.001 for both). Additionally, positive correlations of FUBP1 expression with c-Myc (γ = 0.651, P < 0.001) and the cell proliferation index Ki-67 expression (γ = 0.447, P = 0.004) were indicated using Spearman's rank correlation coefficient. Increased expression of FUBP1 was significantly associated with tumor invasion into the surrounding muscles (P = 0.002). Kaplan-Meier curves demonstrated the association between FUBP1 levels and the patients' local recurrence-free survival (LRFS) (P < 0.001) but not with the overall survival (OS) (P = 0.070). The independent prognostic significance of FUBP1 levels for the LRFS was indicated by multivariate analysis (HR = 4.272; 95% CI, 1.133-16.112; P = 0.032). Our findings demonstrate an association between FUBP1 levels and chordoma progression and prognosis, suggesting that FUBP1 can be used as a biomarker and a potential therapeutic target.

Cushing's syndrome in infancy due to ectopic ACTH secretion by a sacro-coccygeal teratoma.

BACKGROUND: Adenocorticotropic hormone (ACTH)-dependent Cushing's syndrome in infancy is extremely rare. We describe the case of a sacro-coccygeal ectopic ACTH-secreting immature teratoma in an infant who also presented the triad of defects characteristic of Currarino syndrome. CASE PRESENTATION: A girl was born with a large immature teratoma in the sacro-coccygeal region associated with anal atresia. At the age of 7 days, the concentration of α-fetoprotein (AFP) was above the age-specific normal range. Two non-radical surgical excisions of the tumour were performed. At the age of 7 months, she developed polyphagia, acne, hirsutism, hypertension and hypokalemia with elevated ACTH and absence of serum cortisol circadian rhythm. Immunostaining of tumour tissue showed ACTH-immunoreactive cells. Due to unsuccessful therapy with ketoconazole and resistance to antihypertensive medications [blood pressure (BP) 210/160 mmHg], metyrapone was administered, which controlled her ACTH and cortisol levels in the normal range. Following further removal of tumour bulk after three operations during the first year of life, there was a decrease of BP to normal values. CONCLUSIONS: A rare case of ectopic ACTH syndrome causing Cushing's syndrome in infancy in the context of Currarino syndrome is reported. Radical surgery has resulted in excision of the tumour and current control of Cushing's syndrome.

C-reactive protein as a prognostic factor in patients with chordoma of lumbar spine and sacrum--a single center pilot study.

STUDY DESIGN: This is a retrospective, diagnostic study, level IV. BACKGROUND: It appears to be necessary to identify prognostic markers for individual risk estimation for progression and survival in patients with chordoma, a rare disease. Are pre-operative serum levels of C-reactive protein (CRP) associated with disease progression and survival? METHODS: Survival rates of 24 patients (18 males, 6 females) (mean age 67 years (SD ± 16; range 20-85 years); minimum follow-up 2 years, mean follow-up 5 years (SD ± 5; range 2-19 years)) with chordoma of the lower spine and sacrum were assessed with a focus on pre-operative CRP levels. RESULTS: The survival rate of patients with pre-operative CRP level of >1.0 mg/dl was lower than that of patients with a CRP level <1.0 mg/dl (p = 0.01). The estimated 10-year survival of patients with pre-operative CRP values <1.0 and >1.0 mg/dl was 76 and 25%, respectively. CRP remained as an independent survival factor (p = 0.025; CI 95% 1.0-2.6) in multivariable analysis. CONCLUSIONS: Pre-operative CRP levels appear to be a biomarker for disease-specific survival in patients with chordoma of the lumbar spine and sacrum. A validation of our finding with larger cohorts and integration of putative risk factor would further elucidate CRP a surrogate for tumor progression.

Proteomic Analysis of the Uterosacral Ligament in Postmenopausal Women with and without Pelvic Organ Prolapse.

BACKGROUND: Pelvic organ prolapse (POP) is a major health problem in adult women that involves many factors. No proteomic analysis has been conducted exclusively in POP patients. This study aimed to identify the differential expression of proteins that may be involved in POP by proteomic analysis. METHODS: Samples of the uterosacral ligament (USL) were collected from five POP patients and five non-POP patients matched according to age, parity, and menopausal status and analyzed using two-dimensional electrophoresis and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS). Quantitative real-time polymerase chain reaction (qRT-PCR) was used to verify the mRNA expression of proteins that showed differential expression in the proteomic analyses. RESULTS: Proteins differentially expressed between POP and non-POP patients were detected. Eight proteins that were down-regulated in the POP group were identified by MALDI-TOF-MS. These proteins included electron transfer flavoprotein, apolipoprotein A-I, actin, transgelin, cofilin-1, cyclophilin A, myosin, and galectin-1, and their expression was verified by qRT-PCR. CONCLUSION: Using comparative proteomics, we identified eight differentially expressed proteins (including four cytoskeleton proteins and three proteins related to apoptosis) in the USL that may be involved in apoptosis associated with the tissue effects in POP pathophysiology.

Primary intraosseous ganglioneuromatous paraganglioma of the sacrum with immunopositivity for cytokeratin.

BACKGROUND: Paragangliomas are derived from neurosecretory cells believed to be of neural crest origin. A spinal location of paraganglioma is rare and usually presents as an intradural mass. PATIENT AND METHODS: A primary intraosseous paraganglioma of sacrum is extremely unusual, and only 6 cases were reported. In this study, we report a rare case of a 44-year-old man with the complaint of low back pain and lower extremity weakness. Imaging workup, including computerized tomography (CT), and magnetic resonance imaging (MRI) presented an intraosseous sacral lesion with invasion of sacrum in the S1-S3 vertebrae, and extension to L4-L5 spinal canal. The patient underwent subtotal tumor resection, followed by radiation therapy. RESULTS: The morphological and immunohistochemical studies revealed a composite tumor of paraganglioma and ganglioneuroma components, with immunopositivity for cytokeratin. CONCLUSIONS: To the best of our knowledge, this is the first report in the literature demonstrating an intraosseous sacral paraganglioma with these 2 pathological features.

High expression of SPHK1 in sacral chordoma and association with patients' poor prognosis.

Sacral chordoma is an aggressive bone tumor with a high local recurrence rate. Surgery remains the standard treatment because of its resistance to chemotherapy and radiotherapy. However, recurrence occurs frequently even after complete surgical resection. Great effort has been invested in discovering novel biomarkers and therapeutic targets. To date, the molecular mechanism is still unclear. In this study, we evaluated the expression of sphingosine kinase 1 (SPHK1) in 42 sacral chordoma samples and 16 distant normal tissue specimens by immunohistochemical staining. In addition, we analyzed its association with the clinical factors and patients' prognosis. Of all the chordoma samples, 69 % (29/42) showed high expression of SPHK1, whereas, only 19 % (3/16) of distant normal tissues expressed a high level of SPHK1 (p = 0.001). Chi-square analysis revealed that high expression of SPHK1 was significantly correlated with tumor recurrence (p = 0.019) and invasion into surrounding muscle (p = 0.005), while the data did not indicate any association with patients' gender, age, tumor location and size (p > 0.05). Kaplan-Meier survival curve and log-rank test showed that patients with high expression of SPHK1 possessed shorter continuous disease-free survival time. Conclusively, SPHK1 may become a potential biomarker for sacral chordoma in predicting its recurrence and patients' prognosis.

90Y-ibritumomab tiuxetan therapy in allogeneic transplantation in B-cell lymphoma with extensive marrow involvement and chronic lymphocytic leukemia: utility of pretransplantation biodistribution.

BACKGROUND: Biodistribution data to date using In-ibritumomab tiuxetan have been initially obtained in patients with less than 25% lymphomatous bone marrow involvement and adequate hematopoietic synthetic function. In this article we present the results of an analysis of the biodistribution data obtained from a cohort of patients with extensive bone marrow involvement, baseline cytopenias, and chronic lymphocytic leukemia (CLL). MATERIALS AND METHODS: Thirty-nine patients with a diagnosis of B-cell lymphoma or CLL expressing the CD20 antigen, who had failed at least one prior regimen, and had evidence of persistent disease were included in this analysis; however, only 38 of them completed the treatment. Semiquantitative analysis of the biodistribution was performed using regions of interest over the liver, lungs, kidneys, spleen, and sacrum. The observed interpatient variability including higher liver uptake in four patients is discussed. RESULTS: No severe solid organ toxicity was observed at the maximum administered activity of 1184 MBq (32 mCi) Y-ibritumomab tiuxetan. After accounting for differences in marrow involvement, patients with CLL exhibit comparable biodistributions to those with B-NHL. We found that the estimated sacral marrow uptake on 48 h images in patients with bone marrow involvement may be an indicator of bone marrow involvement. There was no correlation between tumor visualization and response to treatment. CONCLUSION: These data suggest that the imaging step is not critical when the administered activity is below 1184 MBq (32 mCi). However, our analysis confirms that the semiquantitative imaging data can be used to identify patients at risk for liver toxicity when higher doses of Y-ibritumomab tiuxetan are used. Patients with CLL can have excellent targeting of disease by In-ibritumomab tiuxetan, indicating potential efficacy in this patient population.

Development of transplantable human chordoma xenograft for preclinical assessment of novel therapeutic strategies.

BACKGROUND: Chordomas are rare and indolent bone tumors that arise in the skull base and mobile spine. Distant metastases occur in >20% of cases, but morbidity and mortality are mainly related to local relapses that affect the majority of patients. Standard chemotherapy has modest activity, whereas new targeted therapies (alone or in combination) have some activity in controlling disease progression. However, the scarcity of preclinical models capable of testing in vivo responses to these therapies hampers the development of new medical strategies. METHODS: In this study, 8 chordoma samples taken from 8 patients were implanted in nude mice. Four engrafted successfully and gave rise to tumor masses that were analyzed histologically, by means of fluorescence in situ hybridization and biochemical techniques. The data relating to each of the mouse tumors were compared with those obtained from the corresponding human tumor. RESULTS: All 4 engraftments retained the histological, genetic and biochemical features of the human tumors they came from. In one epidermal growth factor receptor(EGFR)-positive xenograft, responsiveness to lapatinib was evaluated by comparing the pre- and post treatment findings. The treatment induced a low-level, heterogeneous switching off of EGFR and its downstream signaling effectors. CONCLUSIONS: Overall, this model is very close to human chordoma and represents a new means of undertaking preclinical investigations and developing tailored therapies.

Overexpression of CD40 in sacral chordomas and its correlation with low tumor recurrence.

AIM: To determine the degree of CD40 overexpression in sacral chordomas and its correlation with tumor recurrence. METHODS: CD40 or CD31 overexpression was determined by immunohistochemical staining; the microvessel density (MVD) was calculated according to the CD31 expression. The correlation of CD40 over-expression with tumor recurrence was analyzed. RESULTS: 56% of the specimens from 36 cases of sacral chordomas overexpressed CD40, which is a significantly higher percentage than for the 2 specimens in 10 in normal notochordal tissue (p < 0.05). 36.84% of the specimens of the 19 recurrent cases were CD40 overexpressing, in contrast to less than 76.47% in the no-recurrence group (p < 0.05). Multivariate analysis demonstrated that CD40 overexpression and the resection margins were independent factors contributing to tumor recurrence. The MVD value was 25.71 ± 8.86 mm(-2) in the sacral chordomas and more than 6.63 ± 2.45 mm(-2) in the normal embryonic notochord tissue (p < 0.01). The MVD value in the recurrence group (30.08 ± 7.11 mm(-2)) was significantly higher than that of the no-recurrence group (20.82 ± 8.18 mm(-2); p < 0.05). But the MVD value was significantly lower in the CD40-overexpressing group than in the CD40-less expressing group (p < 0.05). CONCLUSIONS: CD40 was overexpressed in sacral chordomas, and the overexpression was not dependent on the intratumoral MVD. CD40 overexpression was correlated with low recurrence of the tumor, implying that CD40 plays an important role in the antitumor response against sacral chordomas and in the inhibition of tumor recurrence.

High expression of survivin in sacral chordoma.

Chordoma is a rare and invasive malignant tumor which primarily relies on surgical treatments. Anticipation of its recurrence and patient survival longevity has been a critical issue of the treatments. This retrospective study examined the survivin expression of sacral chordoma in 30 patients undergoing surgery in our hospital from January 2000 to July 2010, and compared it with chordoma recurrence. Survivin expression was 70 % positive in 30 patients. The positive expression of survivin with recurrence was significantly higher than that without recurrence (p = 0.017) and was inversely related to the continuous disease-free survival time (p < 0.001). Survivin expression was associated with recurrence. The correlation suggested that the survivin expression could be used as an independent predictor of recurrence and could be a potential bio-target gene of angiogenesis in sacral chordoma.

Difference in expression of collagen type I and matrix metalloproteinase-1 in uterosacral ligaments of women with and without pelvic organ prolapse.

OBJECTIVE: To compare the expression of collagen type I and matrix metalloproteinase-1 (MMP-1) in uterosacral ligament biopsies from women with and without pelvic organ prolapse (POP). STUDY DESIGN: Uterosacral ligament biopsies were obtained from women with POP (n=46) and control subjects (n=49). Immunohistochemistry for collagen type I and MMP-1 was performed on formalin-fixed and paraffin-embedded sections. The two groups were matched for age, body mass index, parity and postmenopausal status. Statistical Package for the Social Sciences Version 13.0 was used for statistical analysis. RESULTS: The expression of collagen type I (p=0.034) and MMP-1 (p=0.038) differed between women with POP and control subjects. There was increased expression of MMP-1 and decreased expression of collagen type 1 in uterosacral ligaments of women with POP compared with control subjects. CONCLUSIONS: This difference indicates a possible relationship between POP and the immunohistochemical expression of collagen type I and MMP-1 in uterosacral ligaments.

Expression of vascular endothelial growth factor and matrix metalloproteinase-9 in sacral chordoma.

Sacral chordoma is a vessel-rich and infiltrative tumor, but the fundamental knowledge of its biological behavior remains unknown. This study was designed to investigate the expression levels and contributions of vascular endothelial growth factor (VEGF) and matrix metalloproteinase-9 (MMP-9) in the angiogenesis and recurrence of sacral chordoma and their correlations. An immunohistochemical method was used to investigate the expression of VEGF, MMP-9, and microvascular density (MVD) in 36 patients with sacral chordoma. Their differences in expressions were statistically analyzed and their correlations with angiogenesis and recurrence were evaluated. The mean MVD of sacral chordomas was significantly higher than that of the adjacent normal tissues (P = 0.033). Immunoreactivity for VEGF and MMP-9 was significantly higher in sacral chordoma tissues than in adjacent normal tissues (P = 0.008, P = 0.005). The mean MVD of VEGF and MMP-9 were statistically higher in positive group than in negative group (P = 0.015, P = 0.004), respectively . Moreover, a significant correlation was found between the VEGF and MMP-9 (P = 0.002). The log-rank test revealed that continuous disease-free survival time (CDFS) was significantly shorter in the MMP-9-positive group than in the MMP-9-negative group (P = 0.019), but the difference in the VEGF-positive group and the VEGF-negative group was not statistically significant (P = 0.938). Our data suggest that VEGF and MMP-9 might act with a synergistic effect and can positively regulate the angiogenesis in sacral chordoma. Positive expression of MMP-9 might indicate the local recurrence of sacral chordoma. The result suggests that some specific drugs which inhibit VEGF, MMP-9, or their receptors may have a good therapeutic effect for sacral chordoma.

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. CASE PRESENTATION: 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. CONCLUSION: 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.