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Solitary spinal extradural plasmacytoma: MR imaging findings in seven cases
Clinical Imaging 39 (2015) 37–41
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Solitary spinal extradural plasmacytoma: MR imaging findings in seven cases Liang Wu a,1, Tao Yang a,1, Xiaofeng Deng b, Chenlong Yang b, Jingyi Fang c, Yulun Xu a,⁎ a b c
Department of Neurosurgery, China National Clinical Research Center for Neurological Diseases, Beijing Tiantan Hospital, Capital Medical University, Beijing, China Department of Neuroradiology, Beijing Tiantan Hospital, Capital Medical University, Beijing, China Department of Neuropathology, Beijing Neurosurgical Institute, Capital Medical University, Beijing, China
a r t i c l e
i n f o
Article history: Received 24 June 2014 Received in revised form 2 October 2014 Accepted 14 October 2014 Keywords: Plasmacytoma Magnetic resonance imaging Spinal tumor Extradural neoplasms
a b s t r a c t Purpose: The aim of this study was to retrospectively review the magnetic resonance (MR) imaging presentation of solitary spinal extradural plasmacytoma (SSEP), which originates from the dura and extends into the extradural space. Materials and methods: MR imaging features of seven patients with SSEP were analyzed. Results: All the tumors were spindle shaped, well defined, and located in the extradural dorsal spinal canal. Most lesions occurred in the thoracic regions with homogeneous enhancement. No bone erosion or exophytic paraspinal mass was noted. Conclusion: SSEP should be considered if a well-circumscribed mass has homogeneous enhancement without bone erosion in the dorsal spinal canal. © 2015 Elsevier Inc. All rights reserved.
1. Introduction Plasma cell tumors present as multiple myeloma or solitary plasmacytoma. Solitary plasmacytoma is characterized by plasma cell proliferation in a single site, without evidence of significant bone marrow plasma-cell infiltration [1,2]. They mostly arise from bone marrow and are known as solitary osseous plasmacytomas [3]. The tumors which arise in extra osseous sites are rarely described and designated as extramedullary plasmacytomas, which account for approximately 3% of all plasma cell tumors [4]. In recent years, the number of reported extramedullary plasmacytomas gradually increased with the increasing application of immunohistochemistry examination. The sites of occurrence included the upper respiratory tissues, lymph nodes, liver, spleen, mediastinum, genital tract, nasopharynx, cranium, and spinal cord [1,3,4]. However, extramedullary plasmacytomas which arise from the spinal dura matter and extend into the extradural space are defined as solitary spinal extradural plasmacytomas (SSEPs) and have been rarely reported. To date, less than 20 cases of SSEPs could be found in the English literature, most of which focused on the clinical and pathological features, treatment, and prognosis. In this paper, we report the radiological features of seven patients with surgically and pathologically proven SSEPs to describe the
⁎ Corresponding author. Department of Neurosurgery, Beijing Tiantan Hospital, Capital Medical University, No. 6, Tiantan Xili, Dongcheng District, Beijing 100050, China. Tel.: +86 8613501285331; fax: +86 10 67096523. E-mail address: [email protected] (Y. Xu). 1 Liang Wu and Tao Yang contributed equally to this work. http://dx.doi.org/10.1016/j.clinimag.2014.10.008 0899-7071/© 2015 Elsevier Inc. All rights reserved.
spectrum of appearance of the specific tumors, with an emphasis on the value of magnetic resonance (MR) imaging features in diagnosis as well as the differential diagnosis. 2. Materials and methods 2.1. Patients This retrospective study was conducted with the approval of the Institutional Review Board of Beijing Tiantan Hospital, Capital Medical University. Seven patients with surgically and pathologically confirmed SSEPs were managed in our hospital between April 2002 and September 2013. Their medical records were well maintained and regular followup was recorded. There were five men and two women, aged from 23 to 66 years with a mean of 50.1 years. The main symptoms were pain (n= 6), progressive numbness (n=5), weakness of the limbs (n= 5), and dysuria (n= 1). The duration of symptoms varied from 2 months to 1 year with a mean of 6 months. Physical examination revealed a decreased strength in the extremities (n=5), degradation of the superficial sensation (n= 6), reduction of the muscular tension (n= 1), and positive Babinski sign (n= 2). All patients underwent preoperative computed tomography (CT) scanning and MR imaging examinations. The surgical resection was performed 3–7 days after the radiological examination, and all the patients underwent laminectomy. Total removal was accomplished in five patients, and decompression of the spinal cord in all the cases was achieved, followed by 30- to 50-Gy radiation therapy in all patients and chemotherapy in five patients. All patients had a follow-up from 10 months to 11 years. Local recurrence was found in
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L. Wu et al. / Clinical Imaging 39 (2015) 37–41
four patients at 4–10 months after treatment, followed by other three patients without recurrence at 28–136 months. Unfortunately, all four patients sustaining recurrence died of disease progression at 6–13 months after treatment. The clinical data of seven patients are summarized in Table 1. 2.2. MR imaging X-ray plain film of spine was initially obtained. To further evaluate the lesion details, all the patients were referred to spinal CT and MR imaging examination. In addition, MR examination of the brain and chest radiograph was also performed to evaluate for metastatic disease. MR images were obtained with a 1.5-T superconductive unit (Gyroscan Intera, Philips Medical Systems, The Netherlands), and a synergy spine coil was used. The sequences included sagittal, coronal turbo spin echo T1- and T2-weighted images, and axial T2-weighted images. The parameters of these sequences were repetition time (TR)/ echo time (TE)=400/10 ms for T1-weighted imaging and TR/TE=3500/ 120 ms for T2-weighted imaging and field of view of 275 mm×325 mm for sagittal imaging, 245 mm×245 mm for axial imaging, and 450 mm×420 mm for coronal imaging, with a matrix of 384×512, 4–6 signals acquisition, and a slice thickness/gap=3/0.3 mm. Contrastenhanced sagittal, coronal, and axial T1-wegithed imaging was obtained after intravenous injection of gadolinium (Magnevist, Schering, Berlin, Germany) with a dosage of 0.2 mmol/kg of body weight. 2.3. Imaging analysis Each case was evaluated by two experienced radiologists who were blinded to the histopathological diagnosis. The final assessment was reached by consensus. The tumor location, size, morphology, margin (well defined or ill defined), signal intensity, contrast enhancement characteristics (homogeneous or heterogeneous), and involvement of foramen were determined. The craniocaudal extent of the lesion was measured compared to the vertebral body length. 2.4. Histopathology The resected tumors were sampled for conventional HE staining and immunohistological staining for immunological markers, including CD20, CD3, CD79a, CD10, CD38, CD138, MUM-1, Ki-67, kappa, lambda, leukocyte common antigen (LCA), S-100, synaptophysin (Syn), vimentin, cytokeratin (CK), chromogranin A (CgA), carcinoembryonic antigen (CEA), and epithelial membrane antigen (EMA). 3. Results The MR imaging findings of all the seven patients are summarized in Table 2. Tumors were located in the cervical (one case), thoracic (five cases), and thoracolumbar (one case) spinal cord regions. Radiological diagnosis indicated the presence of extradural tumors. All the tumors were located in the dorsal spinal canal without spinal congenital malformations (Fig. 1). The lesions were spindle shaped as a longitudinal axis parallel to that of the spine. In two cases, the mass extended
laterally into the adjacent intervertebral foramen with foraminal widening but without exophytic paraspinal mass (Fig. 2). All the cases showed extradural mass, causing the displacement of the spinal cord without signal change, and the subarachnoid space was narrowed. No adjacent bone erosion in the affected spinal canal was found on CT scans in all lesions. The lesions had a size that varied from 30 to 166 mm with an average of three vertebral body lengths. The tumors were well defined in all the patients and had iso- or hypointense signal on T1-weighted imaging and iso- or hyperintense signal on T2weighted imaging. Their signal intensity was usually heterogeneous, but most lesions had homogeneously marked enhancement after the administration of contrast agents. On the basis of preoperative MR imaging, all the patients were misdiagnosed with metastases, lymphomas, or schwannomas. Histologically, all tumors consisted of predominately diffuse welldifferentiated plasma cells with a nodular-like pattern of growth. The immunohistochemistry examination revealed a consistent positive staining for CD38, CD138, and kappa/lambda but negative staining for CD20 in all tumors. The common plasma cell marker MUM-1 was positive in the lesion of five patients (Fig. 3). The detailed immunohistochemistry characteristics of the lesions are shown in Table 3. 4. Discussion Solitary plasmacytoma is an uncommon form of plasma cell disorder. This kind of malignant neoplasm can occur in extramedullary tissue. Solitary extramedullary plasmacytoma is uncommonly encountered in the spinal canal, and SSEP is extremely rare. There have been less than 20 cases of SSEP reported in the literature. It is known to predominate in males, and the mean age of symptom onset is the fifth decade of life [5,6]. In our series, the mean age was in the expected range (50.1 years) with a male predominance (male:female=5:2). The most frequently affected site is the thoracic spinal regions. Similar to those of common intraspinal tumors, the clinical symptoms of SSEPs are numbness, pain, weakness, and sensory or motor changes below the level of lesion, and sphincter dysfunction. Furthermore, pain is the most common initial symptom. In our series, the mean duration between symptom onset and presentation was 6 months (2–12 months), shorter than common intraspinal tumors, which probably reflects the malignant nature and rapid growth pattern of the tumor. The occurrence of SSEPs is exceedingly rare. Compared with common intraspinal tumors, diagnosis and treatment of SSEPs are very critical in preventing unnecessary morbidity, providing accurate information with respect to prognosis, and establishing a reasonable schedule for outpatient follow-up. The pathogenesis of this rare lesion is still unknown, and the origin may be from the dura mater [7]. However, the natural course of SSEP remains unclear because of its rarity. MR imaging is the modality of choice for the diagnosis of intraspinal tumors. Preoperative differential diagnosis for intraspinal tumors is important when planning surgical strategies and determining the extent of the required resection. However, little information was available for the radiological features of the SSEPs. The MR imaging features of the extradural tumor are as follows [4,8,9]: (a) a spindle-shaped tumor attached to the dura mater in a sagittal dimension; (b) the dura mater
Table 1 Clinical characteristics of seven patients with SSEPs Case no.
Age (years), sex
Duration of illness
Tumor location
Treatment
Follow-up
1 2 3 4 5 6 7
62, M 57, M 50, M 62, F 66, M 23, F 31, M
7 months 3 months 3 months 9 months 1 year 6 months 2 months
T12–L1 T5–6 C2–4 T4–6 T4–5 T4–10 T3–4
GTR+RT+CT STR+RT+CT GTR+RT GTR+RT+CT GTR+RT STR+RT+CT GTR+RT+CT
136 mo no rec. 7 mo rec.; 10 mo dead 10 mo rec.; 13 mo dead 4 mo rec.; 6 mo dead 6 mo rec.; 12 mo dead 28 mo no rec. 66 mo no rec.
GTR: gross total resection; CT: chemotherapy; mo: months; rec.: recurrence; RT: radiotherapy; STR: subtotal resection.
L. Wu et al. / Clinical Imaging 39 (2015) 37–41
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Table 2 MR imaging characteristics of seven patients with SSEPs Case no.
Location in the spinal canal
Size (mm)
Margin
T1WI
T2WI
Enhancement
Foramen involvement
1 2 3 4 5 6 7
Dorsal Dorsal Dorsal, lateral Dorsal Dorsal Dorsal Dorsal, lateral
30×16×10 32×14×9 42×26×13 50×15×17 40×15×20 166×10×16 33×15×13
Well defined Well defined Well defined Well defined Well defined Well defined Well defined
Hypoa Slight iso Mixed iso Iso Slight hypo Mixed iso Slight hypo
Hyper Slight hyper Mixed iso Iso Slight hyper Slight hyper Slight hyper
Homo Homo Heter Homo Homo Homo Homo
No No Yes No No No Yes
Hyper: hyperintensity; Hypo: hypointensity; Heter: heterogeneous; Homo: homogeneous; Iso: isointensity; WI: weighted image. a Signal intensity of the spinal cord is the reference for hypo-/iso-/hyperintensity of tumors.
displayed as a slit-like low signal between the tumor and spinal cord in T2-weighted images; and (c) the subarachnoid space narrowed, but the spinal cord shifted to the opposite side. All seven cases in our group displayed the above features and correctly confirmed the localization preoperatively. According to previous limited reports and our cases, the SSEPs usually had heterogeneously hypo- or isointense signal on T1-weighted imaging and hyper- or isointense signal on T2-weighted imaging. SSEP is typically a homogeneously enhancing mass. Thus, the differential diagnosis includes all extradural contrast-enhancing lesions, such as metastasis, lymphoma, schwannoma, and cavernous angioma. The majority of extradural metastatic tumors and lymphomas are usually associated with bone marrow and paravertebral involvement [10]. Lymphomas mostly extend over many vertebral levels, with an encircling rind of anterior extradural tumor effacing the subarachnoid space, and usually have homogeneously low signal intensity on T2-weighted images because of their dense cellularity [11]. Schwannomas usually have paravertebral component with foraminal extension and demonstrate high signal intensity on T2-weighted images, cystic changes, and inhomogeneous enhancement [12]. The SSEPs frequently occurred in the thoracic spine, and some lesions tended to involve foraminal area but without exophytic component and spinal bone destruction. Cavernous angiomas
can show similar MR imaging findings with SSEPs. However, due to a recurrent bleeding tendency, MR imaging features of cavernous angiomas include heterogeneous high and low signal intensity consistent with subacute and chronic hemorrhage and hemosiderin deposition [13], which are absent in the case of SSEPs. However, although the differential diagnosis with other common extradural tumors is important, definitive preoperative diagnosis of SSEP is still difficult based only on MR imaging due to lack of highly specific appearance. Besides conventional MR imaging, results from some recent studies suggest that diffusion-weighted MR imaging (DWI) may become a feasible and potentially useful technique for the evaluation and differentiation of epidural lesions that cause spinal cord compression, although its use in the spine and spinal cord is still relatively uncommon because of the inhomogeneous magnetic environment, the small size of the spinal cord, and the increased motion in and around the spine [14]. Some neoplastic lesions with high cellularity like lymphomas have decreased diffusivity on DWI [15], which may narrow the differential diagnosis. However, no DWI of the spine is performed in any of our cases regretfully, and further investigation on it or other advanced imaging techniques such as positron emission tomography and susceptibilityweighted MR imaging with larger sample sizes of SSEPs is needed.
Fig. 1. Illustration of case 2. A 57-year-old male with bilateral lower extremity numbness and weakness of 3 months. (A) Noncontrast T1-weighted sagittal MR image showed extradural slight isointense mass compressing spinal cord at the T5–6 level. Mass was spindle shaped as longitudinal axis parallel to that of spine. (B) Noncontrast T2-weighted sagittal MR image showed that mass was slightly hyperintense. (C) Postcontrast T1-weighted sagittal MR image showed homogeneously marked enhancement of mass. (D) Postcontrast T1-weighted coronal MR image showed no exophytic component. (E) Postcontrast T1-weighted axial MR image showed mass displacing thecal sac anteriorly.
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Fig. 2. Illustration of case 3. A 50-year-old male with neck pain of 9 months. (A) Noncontrast T1-weighted sagittal MR image showed extradural, well-defined, spindle-shaped, and mixedly isointense mass compressing spinal cord at the C2–4 level. (B) Noncontrast T2-weighted sagittal MR image showed that mass was mixedly isointense. (C) Postcontrast T1-weighted sagittal MR image showed heterogeneously marked enhancement of mass. (D) Postcontrast T1-weighted coronal MR image showed no exophytic component. (E) Postcontrast T1-weighted axial MR image showed mass displacing thecal sac anteriorly and laterally involving foraminal area but without exophytic component.
The prognosis of SSEPs was very poor, and most patients had recurrence or metastasis after the initial treatment [16]. Total resection of the tumor and spinal canal decompression were the primary choice of treatment, while the most effective management had not been defined yet. Radiotherapy and chemotherapy were frequently used postoperatively as an important adjuvant therapy. The progression-free and overall survival time still varies from several months to years after diagnosis, even if both tumor resection and chemotherapy or radiotherapy were attempted [17]. In our group, four patients suffered from recurrence within 1 year after initial treatment and had fatal outcomes due to disease progression in several months. The MR imaging studies on SSEP had never been reported in the English literature. We preliminarily attempted to deepen the knowledge
of imaging appearance of the tumor and to simplify the process of differential diagnosis. However, the present study is limited by its retrospective nature for the last 12 years. Although seven cases in a series seem to be small, the present study included the largest number of SSEP cases yet to be reported. In summary, our study shows that SSEP as a rare tumor entity has variable features at MR imaging but there is a general trend in presentation. When a well-circumscribed thoracic extradural lesion in the dorsal spinal canal without associated bone destructive changes occurs in a middle-aged male patient, SSEPs should be considered as an important differential diagnosis. Preoperative MR imaging is needed for narrowing the differential diagnosis and surgical planning.
Fig. 3. Pathological feature of case 5. A 66-year-old female with bilateral lower extremity numbness and weakness of 1 year. (A) The tumor predominately consisted of diffuse well-differentiated plasma cells with a nodular-like pattern of growth (hematoxylin and eosin stained, original magnification ×200). (B–E) In the immunohistochemical analysis, tumor cells were positive for CD38, CD138, MUM-1, and lambda (B, CD38; C, CD138; D, MUM-1; E, lambda; original magnification ×200).
L. Wu et al. / Clinical Imaging 39 (2015) 37–41
41
Table 3 Immunohistochemistry characteristics of seven patients with SSEPs Case
Positive
Negative
Ki-67
1 2 3 4 5 6 7
LCA, CD138, CD38, kappa, MUM-1 CD38, CD138, MUM-1, kappa CD38, CD138, kappa, lambda CD38, CD138, MUM-1, lambda CD38, CD138, MUM-1, lambda CD38, CD138, kappa CD38, CD138, MUM-1, kappa
lambda, CD20, CD45RO, CgA, S-100, Syn, CD99, CEA, CK, EMA lambda, CD20, CD34 CD20, CD79a, CD10 kappa, CD20, CD34, CD3 kappa, CD20 lambda, MUM-1, CD20, CD3, CD79a, CD10 lambda, CD20, CD34, CD3, CD79a, CD10
5-10% 20% 40% 20% 20% 60 5%
References [1] Zazpe I, Caballero C, Cabada T, Guerrero D, Gallo-Ruiz A, Portillo E. Solitary thoracic intradural extramedullary plasmacytoma. Acta Neurochir (Wien) 2007;149:529–32. [2] Takahashi T, Koshu K, Tominaga T, Takahashi A, Yoshimoto T. Solitary plasmacytoma in the thoracic spine. Two case reports. Neurosurg Rev 1998;21:121–5. [3] Avadhani A, Shetty AP, Rajasekaran S. Isolated extraosseous epidural myeloma presenting with thoracic compressive myelopathy. Spine J 2010;10:e7-10. [4] Haegelen C, Riffaud L, Bernard M, Carsin-Nicol B, Morandi X. Dural plasmacytoma revealing multiple myeloma. Case report. J Neurosurg 2006;104:608–10. [5] Lourbopoulos A, Ioannidis P, Balogiannis I, Stavrinou P, Koletsa T, Karacostas D. Cervical epidural plasmacytoma presenting as ascending paraparesis. Spine J 2011;11:e1–4. [6] Kc Hu, Lin J, Chuang YC, Cheng SJ, Chang KM. Multiple myeloma associated with extramedullary plasmacytoma causing nerve root compression: a case report. J Formos Med Assoc 2001;100:277–80. [7] Kim DH, Yoo SD, Kim SM, Im SJ, Hong DW. Atypical thoracic solitary plasmacytoma. Ann Rehabil Med 2012;36:739–43. [8] Hu S, Hu CH, Hu XY, Wang XM, Dai H, Fang XM, et al. MRI features of spinal epidural angiolipomas. Korean J Radiol 2013;14:810–7. [9] Shah BK, Saifuddin A, Price GJ. Magnetic resonance imaging of spinal plasmacytoma. Clin Radiol 2000;55:439–45.
[10] Boukobza M, Mazel C, Touboul E. Primary vertebral and spinal epidural nonHodgkin's lymphoma with spinal cord compression. Neuroradiology 1996;38: 333–7. [11] Mariniello G, Briganti F, De Caro ML, Maiuri F. Cervical extradural "en-plaque" meningioma. J Neurol Surg A Cent Eur Neurosurg 2012;73:330–3. [12] Jeon JH, Hwang HS, Jeong JH, Park SH, Moon JG, Kim CH. Spinal schwannoma; analysis of 40 cases. J Korean Neurosurg Soc 2008;43:135–8. [13] Santoro A, Piccirilli M, Bristot R, di Norcia V, Salvati M, Delfini R. Extradural spinal cavernous angiomas: report of seven cases. Neurosurg Rev 2005;28:313–9. [14] Bammer R, Fazekas F. Diffusion imaging of the human spinal cord and the vertebral column. Top Magn Reson Imaging 2003;14:461–76. [15] Plank C, Koller A, Mueller-Mang C, Bammer R, Thurnher MM. Diffusion-weighted MR imaging (DWI) in the evaluation of epidural spinal lesions. Neuroradiology 2007;49:977–85. [16] Hong B, Hermann EJ, Reuter C, Brandis A, Krauss JK. Outcome of surgical decompression of spinal mass lesions in non-Hodgkin's lymphoma and plasmacytoma. Clin Neurol Neurosurg 2013;115:2476–81. [17] Voulgaris S, Partheni M, Gousias K, Polyzoidis K, Konstantinou D. Solitary plasmacytoma of the upper cervical spine: therapeutic considerations. J Neurosurg Sci 2008;52:55–9.
Contents lists available at ScienceDirect
Clinical Imaging journal homepage: http://www.clinicalimaging.org
Solitary spinal extradural plasmacytoma: MR imaging findings in seven cases Liang Wu a,1, Tao Yang a,1, Xiaofeng Deng b, Chenlong Yang b, Jingyi Fang c, Yulun Xu a,⁎ a b c
Department of Neurosurgery, China National Clinical Research Center for Neurological Diseases, Beijing Tiantan Hospital, Capital Medical University, Beijing, China Department of Neuroradiology, Beijing Tiantan Hospital, Capital Medical University, Beijing, China Department of Neuropathology, Beijing Neurosurgical Institute, Capital Medical University, Beijing, China
a r t i c l e
i n f o
Article history: Received 24 June 2014 Received in revised form 2 October 2014 Accepted 14 October 2014 Keywords: Plasmacytoma Magnetic resonance imaging Spinal tumor Extradural neoplasms
a b s t r a c t Purpose: The aim of this study was to retrospectively review the magnetic resonance (MR) imaging presentation of solitary spinal extradural plasmacytoma (SSEP), which originates from the dura and extends into the extradural space. Materials and methods: MR imaging features of seven patients with SSEP were analyzed. Results: All the tumors were spindle shaped, well defined, and located in the extradural dorsal spinal canal. Most lesions occurred in the thoracic regions with homogeneous enhancement. No bone erosion or exophytic paraspinal mass was noted. Conclusion: SSEP should be considered if a well-circumscribed mass has homogeneous enhancement without bone erosion in the dorsal spinal canal. © 2015 Elsevier Inc. All rights reserved.
1. Introduction Plasma cell tumors present as multiple myeloma or solitary plasmacytoma. Solitary plasmacytoma is characterized by plasma cell proliferation in a single site, without evidence of significant bone marrow plasma-cell infiltration [1,2]. They mostly arise from bone marrow and are known as solitary osseous plasmacytomas [3]. The tumors which arise in extra osseous sites are rarely described and designated as extramedullary plasmacytomas, which account for approximately 3% of all plasma cell tumors [4]. In recent years, the number of reported extramedullary plasmacytomas gradually increased with the increasing application of immunohistochemistry examination. The sites of occurrence included the upper respiratory tissues, lymph nodes, liver, spleen, mediastinum, genital tract, nasopharynx, cranium, and spinal cord [1,3,4]. However, extramedullary plasmacytomas which arise from the spinal dura matter and extend into the extradural space are defined as solitary spinal extradural plasmacytomas (SSEPs) and have been rarely reported. To date, less than 20 cases of SSEPs could be found in the English literature, most of which focused on the clinical and pathological features, treatment, and prognosis. In this paper, we report the radiological features of seven patients with surgically and pathologically proven SSEPs to describe the
⁎ Corresponding author. Department of Neurosurgery, Beijing Tiantan Hospital, Capital Medical University, No. 6, Tiantan Xili, Dongcheng District, Beijing 100050, China. Tel.: +86 8613501285331; fax: +86 10 67096523. E-mail address: [email protected] (Y. Xu). 1 Liang Wu and Tao Yang contributed equally to this work. http://dx.doi.org/10.1016/j.clinimag.2014.10.008 0899-7071/© 2015 Elsevier Inc. All rights reserved.
spectrum of appearance of the specific tumors, with an emphasis on the value of magnetic resonance (MR) imaging features in diagnosis as well as the differential diagnosis. 2. Materials and methods 2.1. Patients This retrospective study was conducted with the approval of the Institutional Review Board of Beijing Tiantan Hospital, Capital Medical University. Seven patients with surgically and pathologically confirmed SSEPs were managed in our hospital between April 2002 and September 2013. Their medical records were well maintained and regular followup was recorded. There were five men and two women, aged from 23 to 66 years with a mean of 50.1 years. The main symptoms were pain (n= 6), progressive numbness (n=5), weakness of the limbs (n= 5), and dysuria (n= 1). The duration of symptoms varied from 2 months to 1 year with a mean of 6 months. Physical examination revealed a decreased strength in the extremities (n=5), degradation of the superficial sensation (n= 6), reduction of the muscular tension (n= 1), and positive Babinski sign (n= 2). All patients underwent preoperative computed tomography (CT) scanning and MR imaging examinations. The surgical resection was performed 3–7 days after the radiological examination, and all the patients underwent laminectomy. Total removal was accomplished in five patients, and decompression of the spinal cord in all the cases was achieved, followed by 30- to 50-Gy radiation therapy in all patients and chemotherapy in five patients. All patients had a follow-up from 10 months to 11 years. Local recurrence was found in
38
L. Wu et al. / Clinical Imaging 39 (2015) 37–41
four patients at 4–10 months after treatment, followed by other three patients without recurrence at 28–136 months. Unfortunately, all four patients sustaining recurrence died of disease progression at 6–13 months after treatment. The clinical data of seven patients are summarized in Table 1. 2.2. MR imaging X-ray plain film of spine was initially obtained. To further evaluate the lesion details, all the patients were referred to spinal CT and MR imaging examination. In addition, MR examination of the brain and chest radiograph was also performed to evaluate for metastatic disease. MR images were obtained with a 1.5-T superconductive unit (Gyroscan Intera, Philips Medical Systems, The Netherlands), and a synergy spine coil was used. The sequences included sagittal, coronal turbo spin echo T1- and T2-weighted images, and axial T2-weighted images. The parameters of these sequences were repetition time (TR)/ echo time (TE)=400/10 ms for T1-weighted imaging and TR/TE=3500/ 120 ms for T2-weighted imaging and field of view of 275 mm×325 mm for sagittal imaging, 245 mm×245 mm for axial imaging, and 450 mm×420 mm for coronal imaging, with a matrix of 384×512, 4–6 signals acquisition, and a slice thickness/gap=3/0.3 mm. Contrastenhanced sagittal, coronal, and axial T1-wegithed imaging was obtained after intravenous injection of gadolinium (Magnevist, Schering, Berlin, Germany) with a dosage of 0.2 mmol/kg of body weight. 2.3. Imaging analysis Each case was evaluated by two experienced radiologists who were blinded to the histopathological diagnosis. The final assessment was reached by consensus. The tumor location, size, morphology, margin (well defined or ill defined), signal intensity, contrast enhancement characteristics (homogeneous or heterogeneous), and involvement of foramen were determined. The craniocaudal extent of the lesion was measured compared to the vertebral body length. 2.4. Histopathology The resected tumors were sampled for conventional HE staining and immunohistological staining for immunological markers, including CD20, CD3, CD79a, CD10, CD38, CD138, MUM-1, Ki-67, kappa, lambda, leukocyte common antigen (LCA), S-100, synaptophysin (Syn), vimentin, cytokeratin (CK), chromogranin A (CgA), carcinoembryonic antigen (CEA), and epithelial membrane antigen (EMA). 3. Results The MR imaging findings of all the seven patients are summarized in Table 2. Tumors were located in the cervical (one case), thoracic (five cases), and thoracolumbar (one case) spinal cord regions. Radiological diagnosis indicated the presence of extradural tumors. All the tumors were located in the dorsal spinal canal without spinal congenital malformations (Fig. 1). The lesions were spindle shaped as a longitudinal axis parallel to that of the spine. In two cases, the mass extended
laterally into the adjacent intervertebral foramen with foraminal widening but without exophytic paraspinal mass (Fig. 2). All the cases showed extradural mass, causing the displacement of the spinal cord without signal change, and the subarachnoid space was narrowed. No adjacent bone erosion in the affected spinal canal was found on CT scans in all lesions. The lesions had a size that varied from 30 to 166 mm with an average of three vertebral body lengths. The tumors were well defined in all the patients and had iso- or hypointense signal on T1-weighted imaging and iso- or hyperintense signal on T2weighted imaging. Their signal intensity was usually heterogeneous, but most lesions had homogeneously marked enhancement after the administration of contrast agents. On the basis of preoperative MR imaging, all the patients were misdiagnosed with metastases, lymphomas, or schwannomas. Histologically, all tumors consisted of predominately diffuse welldifferentiated plasma cells with a nodular-like pattern of growth. The immunohistochemistry examination revealed a consistent positive staining for CD38, CD138, and kappa/lambda but negative staining for CD20 in all tumors. The common plasma cell marker MUM-1 was positive in the lesion of five patients (Fig. 3). The detailed immunohistochemistry characteristics of the lesions are shown in Table 3. 4. Discussion Solitary plasmacytoma is an uncommon form of plasma cell disorder. This kind of malignant neoplasm can occur in extramedullary tissue. Solitary extramedullary plasmacytoma is uncommonly encountered in the spinal canal, and SSEP is extremely rare. There have been less than 20 cases of SSEP reported in the literature. It is known to predominate in males, and the mean age of symptom onset is the fifth decade of life [5,6]. In our series, the mean age was in the expected range (50.1 years) with a male predominance (male:female=5:2). The most frequently affected site is the thoracic spinal regions. Similar to those of common intraspinal tumors, the clinical symptoms of SSEPs are numbness, pain, weakness, and sensory or motor changes below the level of lesion, and sphincter dysfunction. Furthermore, pain is the most common initial symptom. In our series, the mean duration between symptom onset and presentation was 6 months (2–12 months), shorter than common intraspinal tumors, which probably reflects the malignant nature and rapid growth pattern of the tumor. The occurrence of SSEPs is exceedingly rare. Compared with common intraspinal tumors, diagnosis and treatment of SSEPs are very critical in preventing unnecessary morbidity, providing accurate information with respect to prognosis, and establishing a reasonable schedule for outpatient follow-up. The pathogenesis of this rare lesion is still unknown, and the origin may be from the dura mater [7]. However, the natural course of SSEP remains unclear because of its rarity. MR imaging is the modality of choice for the diagnosis of intraspinal tumors. Preoperative differential diagnosis for intraspinal tumors is important when planning surgical strategies and determining the extent of the required resection. However, little information was available for the radiological features of the SSEPs. The MR imaging features of the extradural tumor are as follows [4,8,9]: (a) a spindle-shaped tumor attached to the dura mater in a sagittal dimension; (b) the dura mater
Table 1 Clinical characteristics of seven patients with SSEPs Case no.
Age (years), sex
Duration of illness
Tumor location
Treatment
Follow-up
1 2 3 4 5 6 7
62, M 57, M 50, M 62, F 66, M 23, F 31, M
7 months 3 months 3 months 9 months 1 year 6 months 2 months
T12–L1 T5–6 C2–4 T4–6 T4–5 T4–10 T3–4
GTR+RT+CT STR+RT+CT GTR+RT GTR+RT+CT GTR+RT STR+RT+CT GTR+RT+CT
136 mo no rec. 7 mo rec.; 10 mo dead 10 mo rec.; 13 mo dead 4 mo rec.; 6 mo dead 6 mo rec.; 12 mo dead 28 mo no rec. 66 mo no rec.
GTR: gross total resection; CT: chemotherapy; mo: months; rec.: recurrence; RT: radiotherapy; STR: subtotal resection.
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Table 2 MR imaging characteristics of seven patients with SSEPs Case no.
Location in the spinal canal
Size (mm)
Margin
T1WI
T2WI
Enhancement
Foramen involvement
1 2 3 4 5 6 7
Dorsal Dorsal Dorsal, lateral Dorsal Dorsal Dorsal Dorsal, lateral
30×16×10 32×14×9 42×26×13 50×15×17 40×15×20 166×10×16 33×15×13
Well defined Well defined Well defined Well defined Well defined Well defined Well defined
Hypoa Slight iso Mixed iso Iso Slight hypo Mixed iso Slight hypo
Hyper Slight hyper Mixed iso Iso Slight hyper Slight hyper Slight hyper
Homo Homo Heter Homo Homo Homo Homo
No No Yes No No No Yes
Hyper: hyperintensity; Hypo: hypointensity; Heter: heterogeneous; Homo: homogeneous; Iso: isointensity; WI: weighted image. a Signal intensity of the spinal cord is the reference for hypo-/iso-/hyperintensity of tumors.
displayed as a slit-like low signal between the tumor and spinal cord in T2-weighted images; and (c) the subarachnoid space narrowed, but the spinal cord shifted to the opposite side. All seven cases in our group displayed the above features and correctly confirmed the localization preoperatively. According to previous limited reports and our cases, the SSEPs usually had heterogeneously hypo- or isointense signal on T1-weighted imaging and hyper- or isointense signal on T2-weighted imaging. SSEP is typically a homogeneously enhancing mass. Thus, the differential diagnosis includes all extradural contrast-enhancing lesions, such as metastasis, lymphoma, schwannoma, and cavernous angioma. The majority of extradural metastatic tumors and lymphomas are usually associated with bone marrow and paravertebral involvement [10]. Lymphomas mostly extend over many vertebral levels, with an encircling rind of anterior extradural tumor effacing the subarachnoid space, and usually have homogeneously low signal intensity on T2-weighted images because of their dense cellularity [11]. Schwannomas usually have paravertebral component with foraminal extension and demonstrate high signal intensity on T2-weighted images, cystic changes, and inhomogeneous enhancement [12]. The SSEPs frequently occurred in the thoracic spine, and some lesions tended to involve foraminal area but without exophytic component and spinal bone destruction. Cavernous angiomas
can show similar MR imaging findings with SSEPs. However, due to a recurrent bleeding tendency, MR imaging features of cavernous angiomas include heterogeneous high and low signal intensity consistent with subacute and chronic hemorrhage and hemosiderin deposition [13], which are absent in the case of SSEPs. However, although the differential diagnosis with other common extradural tumors is important, definitive preoperative diagnosis of SSEP is still difficult based only on MR imaging due to lack of highly specific appearance. Besides conventional MR imaging, results from some recent studies suggest that diffusion-weighted MR imaging (DWI) may become a feasible and potentially useful technique for the evaluation and differentiation of epidural lesions that cause spinal cord compression, although its use in the spine and spinal cord is still relatively uncommon because of the inhomogeneous magnetic environment, the small size of the spinal cord, and the increased motion in and around the spine [14]. Some neoplastic lesions with high cellularity like lymphomas have decreased diffusivity on DWI [15], which may narrow the differential diagnosis. However, no DWI of the spine is performed in any of our cases regretfully, and further investigation on it or other advanced imaging techniques such as positron emission tomography and susceptibilityweighted MR imaging with larger sample sizes of SSEPs is needed.
Fig. 1. Illustration of case 2. A 57-year-old male with bilateral lower extremity numbness and weakness of 3 months. (A) Noncontrast T1-weighted sagittal MR image showed extradural slight isointense mass compressing spinal cord at the T5–6 level. Mass was spindle shaped as longitudinal axis parallel to that of spine. (B) Noncontrast T2-weighted sagittal MR image showed that mass was slightly hyperintense. (C) Postcontrast T1-weighted sagittal MR image showed homogeneously marked enhancement of mass. (D) Postcontrast T1-weighted coronal MR image showed no exophytic component. (E) Postcontrast T1-weighted axial MR image showed mass displacing thecal sac anteriorly.
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L. Wu et al. / Clinical Imaging 39 (2015) 37–41
Fig. 2. Illustration of case 3. A 50-year-old male with neck pain of 9 months. (A) Noncontrast T1-weighted sagittal MR image showed extradural, well-defined, spindle-shaped, and mixedly isointense mass compressing spinal cord at the C2–4 level. (B) Noncontrast T2-weighted sagittal MR image showed that mass was mixedly isointense. (C) Postcontrast T1-weighted sagittal MR image showed heterogeneously marked enhancement of mass. (D) Postcontrast T1-weighted coronal MR image showed no exophytic component. (E) Postcontrast T1-weighted axial MR image showed mass displacing thecal sac anteriorly and laterally involving foraminal area but without exophytic component.
The prognosis of SSEPs was very poor, and most patients had recurrence or metastasis after the initial treatment [16]. Total resection of the tumor and spinal canal decompression were the primary choice of treatment, while the most effective management had not been defined yet. Radiotherapy and chemotherapy were frequently used postoperatively as an important adjuvant therapy. The progression-free and overall survival time still varies from several months to years after diagnosis, even if both tumor resection and chemotherapy or radiotherapy were attempted [17]. In our group, four patients suffered from recurrence within 1 year after initial treatment and had fatal outcomes due to disease progression in several months. The MR imaging studies on SSEP had never been reported in the English literature. We preliminarily attempted to deepen the knowledge
of imaging appearance of the tumor and to simplify the process of differential diagnosis. However, the present study is limited by its retrospective nature for the last 12 years. Although seven cases in a series seem to be small, the present study included the largest number of SSEP cases yet to be reported. In summary, our study shows that SSEP as a rare tumor entity has variable features at MR imaging but there is a general trend in presentation. When a well-circumscribed thoracic extradural lesion in the dorsal spinal canal without associated bone destructive changes occurs in a middle-aged male patient, SSEPs should be considered as an important differential diagnosis. Preoperative MR imaging is needed for narrowing the differential diagnosis and surgical planning.
Fig. 3. Pathological feature of case 5. A 66-year-old female with bilateral lower extremity numbness and weakness of 1 year. (A) The tumor predominately consisted of diffuse well-differentiated plasma cells with a nodular-like pattern of growth (hematoxylin and eosin stained, original magnification ×200). (B–E) In the immunohistochemical analysis, tumor cells were positive for CD38, CD138, MUM-1, and lambda (B, CD38; C, CD138; D, MUM-1; E, lambda; original magnification ×200).
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Table 3 Immunohistochemistry characteristics of seven patients with SSEPs Case
Positive
Negative
Ki-67
1 2 3 4 5 6 7
LCA, CD138, CD38, kappa, MUM-1 CD38, CD138, MUM-1, kappa CD38, CD138, kappa, lambda CD38, CD138, MUM-1, lambda CD38, CD138, MUM-1, lambda CD38, CD138, kappa CD38, CD138, MUM-1, kappa
lambda, CD20, CD45RO, CgA, S-100, Syn, CD99, CEA, CK, EMA lambda, CD20, CD34 CD20, CD79a, CD10 kappa, CD20, CD34, CD3 kappa, CD20 lambda, MUM-1, CD20, CD3, CD79a, CD10 lambda, CD20, CD34, CD3, CD79a, CD10
5-10% 20% 40% 20% 20% 60 5%
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