|Year : 2020 | Volume
| Issue : 1 | Page : 56-59
Metastatic spindle cell tumor in sacrum
Umesh Chandra Dutta1, ML A Rahman2, Naznin Rashid1, R Barua1
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 Submission||16-Apr-2019|
|Date of Acceptance||12-Apr-2020|
|Date of Web Publication||2-Jul-2020|
Dr. Umesh Chandra Dutta
Lab and Blood Bank, Rahman Hospitals Pvt. Ltd., VIP Road, Sixmile, Khanapara, Guwahati, Assam
Source of Support: None, Conflict of Interest: None
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
| Introduction|| |
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., GIST accounts for 0.1%–3% of all gastrointestinal (GI) neoplasms. The most frequent site of occurrence is the stomach (60%), followed by the small bowel (35%) and other sites (colon, rectum, and esophagus <5%)., The liver is the most common site of metastasis at both presentation and relapse., The peritoneum is the second-most common site of metastasis, whereas bone metastasis is rare., 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., 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|| |
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].
| Discussion|| |
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., These tumors have an unpredictable clinical behavior ranging from benign to frankly malignant with approximately 10%–30% of GISTs exhibit malignant behavior. There are only a few reported cases in the literature of patients with GIST metastases to the bone.,, 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. Bone metastases can be diagnosed rarely at disease presentation, however, it presents more frequently at disease relapse. The most frequent sites of bone metastases reported in many case series were spine and pelvis., 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.
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. 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|| |
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.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4]