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Table of Contents
Year : 2020  |  Volume : 3  |  Issue : 1  |  Page : 56-59

Metastatic spindle cell tumor in sacrum

1 Department of Pathology and Blood Bank, Rahman Hospitals Pvt. Ltd., Guwahati, Assam, India
2 Department of Neurosurgery, Rahman Hospitals Pvt. Ltd., Guwahati, Assam, India

Date of Submission16-Apr-2019
Date of Acceptance12-Apr-2020
Date of Web Publication2-Jul-2020

Correspondence Address:
Dr. Umesh Chandra Dutta
Lab and Blood Bank, Rahman Hospitals Pvt. Ltd., VIP Road, Sixmile, Khanapara, Guwahati, Assam
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/IJNO.IJNO_5_19

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Spindle cell tumours metastatic to bone are rare. A gastrointestinal stromal tumor (GIST) with spindle cell histology is one such tumour that may rarely metastasize to bone and pose great diagnostic or therapeutic challenge for the clinicians. Their symptoms are minimal in the early stage and may go unnoticed before being detected. At the time of presentation, the tumor often metastasizes to other parts of the body, rarely to bone. GISTs are defined as spindle cell, epitheloid, or occasionally pleomorphic mesenchymal tumors of the gastrointestinal tract, which express the KIT protein (CD117), and/or DOG1.Cytological and histological features of metastatic GIST are variable. We present here a rare case of metastatic spindle cell tumour (without clinical evidence of primary) involving sacrum with histopathological & immunohistochemical features of GIST.

Keywords: DOG1, gastrointestinal stromal tumor, Ki-67, metastatic, diagnosis

How to cite this article:
Dutta UC, A Rahman M L, Rashid N, Barua R. Metastatic spindle cell tumor in sacrum. Int J Neurooncol 2020;3:56-9

How to cite this URL:
Dutta UC, A Rahman M L, Rashid N, Barua R. Metastatic spindle cell tumor in sacrum. Int J Neurooncol [serial online] 2020 [cited 2022 Jun 27];3:56-9. Available from: https://www.Internationaljneurooncology.com/text.asp?2020/3/1/56/288792

  Introduction Top

Spindle cell tumors metastatic to bone are rare. A gastrointestinal stromal tumor (GIST) with spindle cell histology is one such tumor that may rarely metastasize to bone and pose great diagnostic or therapeutic challenge for the clinicians. In the small series in the literature, their proportion is found to be low.[1],[2] GIST accounts for 0.1%–3% of all gastrointestinal (GI) neoplasms.[3] The most frequent site of occurrence is the stomach (60%), followed by the small bowel (35%) and other sites (colon, rectum, and esophagus <5%).[1],[3] The liver is the most common site of metastasis at both presentation and relapse.[2],[4] The peritoneum is the second-most common site of metastasis, whereas bone metastasis is rare.[2],[4] Histopathologically and immunohistochemically, GISTs are defined as spindle cell, epithelioid, or occasionally pleomorphic mesenchymal tumors of the GI tract, which express the KIT protein (CD117, stem cell factor receptor) and/or DOG1.[1],[3] These tumors usually occur in middle-aged and older patients, with no gender predominance. The symptoms are minimal in the early stage and may go unnoticed. By the time of presentation, the tumor attains a large size and spreads to other organs including lung and liver. However, spinal involvement of metastatic GIST is very rare. In the recent years, tremendous progress has been made in understanding and treating the underlying pathophysiology of GIST; there is very high expression of activating Ki 67 and DOG1 resulting in successful treatment with tyrosine kinase inhibitors. The aim of this study is to investigate new and more practical tissue markers, such as DOG1 and Ki-67 to specify the GIST diagnosis.

  Case Report Top

A 57-year-old female was admitted with complaints of low back pain radiating to left thigh with tingling sensation in the left leg for 3 months. She was a diagnosed case of type 2 diabetes. She was initially diagnosed as chordoma in an outside hospital on the basis of magnetic resonance imaging (MRI) of LS spine and histopathologically diagnosed as fibrosarcoma in the same hospital 3 months before attending our hospital.

MRI shows a large approximately 7 cm × 6 cm × 5.5 cm lobulated altered signal intensity lesion in the sacrum predominantly involving S1 and S2 in the middle and left lateral mass. Mild annular enhancement was seen after contrast. Upper sacroiliac joint appears partially involved. There is associated sacral spinal canal stenosis and compression in the nerve root. Radiologically, a diagnosis of chordoma was suggested. A diagnosis of fibrosarcoma was offered on core biopsy specimen by an outside hospital.

In our institute, an incisional biopsy was performed and sent for cytological and histopathological evaluation. Cytologically, the lesion showed features of a spindle cell tumor as shown in [Figure 1] and [Figure 2].
Figure 1: Cytological features of the sacral mass showing atypical spindle cells (MGG, ×400)

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Figure 2: Cytological features of the sacral mass showing atypical spindle cells with tissue fragment (MGG, ×400)

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Histopathological Examination (HPE) showed a mass lesion comprising spindle cells arranged in sweeping intersecting fascicles with cells showing mild pleomorphism, elongated vesicular nuclei with moderate eosinophilic cytoplasm as observed from [Figure 3] and [Figure 4]. Some cells reveal wavy tapering ends with distinct nucleoli. Occasional mitotic figures with few cleft like spaces were noted. A differential diagnosis of the mass was made with the possibilities of GIST/solitary fibrous tumor/synovial sarcoma. Immunohistochemistry (IHC) revealed the following findings:
Figure 3: Histopathological features showing spindle cells arranged in sweeping intersecting fascicles (H and E, ×400)

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Figure 4: Spindle cells revealing nuclei with wavy tapering ends, occasional distinct nucleoli, and few mitotic figures. Scattered cleft like spaces are also noted (H and E, ×400)

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Tests for STAT, CD34, S-100, and desmin are found to be negative. Cytogenetic studies did not reveal specific chromosomal translocation: t (X; 18) (p11.2; q11.2). These findings excluded synovial sarcoma and solitary fibrous tumor from the list of diagnoses.

The lesion was finally diagnosed as GIST – spindle cell type based on histomorphological, IHC features, and cytogenetic findings as shown in [Table 1].
Table 1: Showing Immunoreactive score of the tumour

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  Discussion Top

GISTs are defined histologically as pleomorphic mesenchymal tumors of the GI tract composed of spindle cells, epithelioid cells, or a combination of both that express the KIT protein (CD 117) and in most cases DOG1 on IHC.[4],[5] These tumors have an unpredictable clinical behavior ranging from benign to frankly malignant with approximately 10%–30% of GISTs exhibit malignant behavior.[1] There are only a few reported cases in the literature of patients with GIST metastases to the bone.[2],[6],[7] Over all the tumors constitute 0.1%–0.3% of all GI tumors and with a reported incidence of 6% metastasis to bone. One study reported 13 out of 278 patients (5%) with GIST had bone metastases. In another series of 190 GIST patients, only six (3.2%) had bone metastases.[8] Bone metastases can be diagnosed rarely at disease presentation, however, it presents more frequently at disease relapse.[9] The most frequent sites of bone metastases reported in many case series were spine and pelvis.[9],[10] Our case had metastasis in the sacrum.

Clinically, bone metastases are mostly symptomatic and revealed by bone fractures or bone pain (as in our patient) or spinal cord compression syndrome but they can be asymptomatic and are an incidental finding of the occasion of the practice of computed tomography or positron emission tomography-scan.[9]

In a study of large series, HPE revealed 87 (78.4%) patients had spindle, 16 (14.4%) patients had mixed type and 8 (7.2%) patients had epithelioid cell character. Review of literature does not reveal any difference of histological types of primary and metastatic GIST. However, spindle cell variant is cited to be more common in metastatic GIST. The first two differential diagnosis of the case were those of solitary fibrous tumor and synovial sarcoma and as such the IHC and Cytogenetics tests were carried out to rule out both. Subsequently DOG1 test was done which showed positive result. The specificity and the sensitivity of DOG1 in GIST diagnosis has been studied by some authors. Several studies indicate sensitivity range of DOG1 as 75%–95% with a specificity up to 98%. DOG1 expression has also been emphasized as an important test in the diagnosis of c-kit negative cases. Although Ki-67 was not found a statistically significant prognostic factor for overall survival, it is found to be strongly correlated with mitotic index which is a well-known standard prognostic factor. On the other hand, Ki-67 can be a stronger candidate for prognostic factor instead of mitotic index to identify the proliferative cells out of mitotic phase but this statement needs be prospectively validated on studies with large number of patients.[11] DOG1 seems to be an important diagnostic tool for clinically suspected GIST diagnosis in both advanced and early staged patients whose tumors are c-kit expression negative. The patient was advised to undergo further investigation including endoscopic examination of the GI tract for the detection of primary GIST but was lost to the follow-up.

  Conclusion Top

Although rare, the clinicians as well as the pathologists should be well versed and aware of a metastasis of GIST especially when encountering a spindle cell lesion. Here, we present a case of GIST metastatic to sacrum that is fully documented by pathological, immunohistochemical, and molecular analysis.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.

  References Top

Kindblom LG, Remotti HE, Aldenborg F, Meis-Kindblom JM. Gastrointestinal pacemaker cell tumor (GIPACT): Gastrointestinal stromal tumors show phenotypic characteristics of the interstitial cells of Cajal. Am J Pathol 1998;152:1259-69.  Back to cited text no. 1
DeMatteo RP, Lewis JJ, Leung D, Mudan SS, Woodruff JM, Brennan MF. Two hundred gastrointestinal stromal tumors: Recurrence patterns and prognostic factors for survival. Ann Surg 2000;231:51-8.  Back to cited text no. 2
Goettsch WG, Bos SD, Breekveldt-Postma N, Casparie M, Herings RM, Hogendoorn PC. Incidence of gastrointestinal stromal tumours is underestimated: Results of a nation-wide study. Eur J Cancer 2005;41:2868-72.  Back to cited text no. 3
Burkill GJ, Badran M, Al-Muderis O, Meirion Thomas J, Judson IR, Fisher C, et al. Malignant gastrointestinal stromal tumor: Distribution, imaging features, and pattern of metastatic spread. Radiology 2003;226:527-32.  Back to cited text no. 4
Kaku S, Tanaka T, Ohtuka T, Seki K, Sawauchi S, Numoto RT, et al. Perisacral gastrointestinal stromal tumor with intracranial metastasis. Case report. Neurol Med Chir (Tokyo) 2006;46:254-7.  Back to cited text no. 5
Tran T, Davila JA, El-Serag HB. The epidemiology of malignant gastrointestinal stromal tumors: An analysis of 1,458 cases from 1992 to 2000. Am J Gastroenterol 2005;100:162-8.  Back to cited text no. 6
Slimack NP, Liu JC, Koski T, McClendon J Jr., O'Shaughnessy BA. Metastatic gastrointestinal stromal tumor to the thoracic and lumbar spine:First reported case and surgical treatment. Spine J 2012;12:e7-12.  Back to cited text no. 7
Suzuki K, Yasuda T, Nagao K, Hori T, Watanabe K, Kanamori M, et al. Bone metastasis of a gastrointestinal stromal tumor: A report of two cases. Oncol Lett 2015;9:1814-8.  Back to cited text no. 8
Jati A, Tatlı S, Morgan JA, Glickman JN, Demetri GD, Van den Abbele A, et al. Imaging features of bone metastases in patients with gastrointestinal stromal tumors. Diagn Interv Radiol 2012;18:391-6.  Back to cited text no. 9
Bertulli R, Fumagalli E, Coco P, Messina A, Morosi C, Dileo P, et al. Fondazione IRCCS Istituto Nazionale dei Tumori, Milan, Italy: Unusual metastatic sites in gastrointestinal stromal tumor (GIST). ASCO Meet Abstr 2009;27:10566.  Back to cited text no. 10
Sözütek D, Yanık S, Akkoca AN, Sözütek A, Ozdemir ZT, Avşar CU, et al. Diagnostic and prognostic roles of DOG1 and Ki-67, in GIST patients with localized or advanced/metastatic disease. Int J Clin Exp Med 2014;7:1914-22.  Back to cited text no. 11


  [Figure 1], [Figure 2], [Figure 3], [Figure 4]

  [Table 1]


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