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CT imaging findings of abdominopelvic desmoplastic small round cell tumors: Correlation with histopathologic findings
European Journal of Radiology 80 (2011) 269–273
Contents lists available at ScienceDirect
European Journal of Radiology journal homepage: www.elsevier.com/locate/ejrad
CT, MRI, and FDG-PET/CT imaging findings of abdominopelvic desmoplastic small round cell tumors: Correlation with histopathologic findings Wei-dong Zhang a,b,1, Chuan-xing Li a,b,1, Qing-yu Liu c,2, Ying-ying Hu a,b,1, Yun Cao a,d,1, Jin-hua Huang a,b,∗ a
State Key Laboratory of Oncology in South China, 651 Dongfengdong Road, Guangzhou, Guangdong 510060, PR China Department of Radiology, Cancer Center, Sun Yat-sen University, Guangzhou, Guangdong 510060, PR China c Department of Radiology, No. 2 Affiliated Hospital, 107 Yanjiangxi Road, Sun Yat-sen University, Guangzhou, Guangdong 510120, PR China d Department of Pathology, Cancer Center, Sun Yat-sen University, Guangzhou, Guangdong 510060, PR China b
a r t i c l e
i n f o
Article history: Received 5 May 2010 Received in revised form 23 June 2010 Accepted 25 June 2010 Keywords: Desmoplastic small round cell tumor Computed tomography Magnetic resonance imaging FDG-PET/CT imaging Pathology
a b s t r a c t Objective: To analyze computed tomography (CT), magnetic resonance imaging (MRI), and fluorodeoxyglucose-positron emission tomography (FDG-PET)/CT imaging features of abdominopelvic desmoplastic small round cell tumor (DSRCT) and to improve the diagnostic efficacy of these techniques for the detection of such tumor. Methods: We retrospectively analyzed 7 cases of abdominopelvic DSRCT confirmed by histopathologic analysis. Among the 7 patients, 5 patients had undergone CT scanning, 2 of which were also examined with FDG-PET/CT imaging, and 2 had undergone MRI. Unenhanced and contrast-enhanced examinations were performed in all patients, and 2 patients had also undergone dynamic CT contrast-enhanced examinations. Image characteristics, such as shape, size, number, edge, attenuation, and intensity of each lesion before and after contrast enhancement were analyzed and compared with the pathomorphology of the tumors. Results: Multiple large masses in the abdominopelvis were detected in 6 cases, and a large mass in the pelvis was detected in 1 case. Six cases showed largest mass in pelvis, and 1 case in mesentery. None of the masses had a definite organ origin. CT showed soft tissue masses with patchy foci of hypodense areas. MR T1-weighted images revealed lesions with mild hypointense areas and patchy hypointense areas in 2 cases and lesions with patchy hyperintense areas in 1 case. T2-weighted images showed lesions with mixed isointense and hyperintense areas in 1 case and lesions with mixed hypointense, isointense, and hyperintense areas in another. Contrast-enhanced CT and T1-weighted images showed mildly heterogeneous enhancement of the lesions. Other associated findings included peritoneal seeding (n = 3), peritoneal effusions (n = 3), hepatic metastasis (n = 2), bone metastasis (n = 1), and mesenteric and retroperitoneal lymphadenopathy (n = 4). FDG-PET/CT showed multiple nodular foci of increased metabolic activity in the abdominopelvic masses, in the hepatic and right ilium in 1 case and foci of increased metabolic activity in the pelvic mass in another. Conclusion: Radiological findings of DSRCT include multiple masses with heterogeneous density/intensity and without an organ origin. Other common associated findings include peritoneal seeding, peritoneal effusion, hepatic metastasis, and retroperitoneal lymphadenopathy. DSRCT should be considered in the differential diagnosis of regional tumors in adolescents and young adults. FDG-PET/CT can provide additional information on the stage of the tumor. © 2010 Elsevier Ireland Ltd. All rights reserved.
∗ Corresponding author at: State Key Laboratory of Oncology in South China, 651 Dongfengdong Road, Guangzhou, Guangdong 510060, PR China. Tel.: +86 20 87343217; fax: +86 20 87343392. E-mail addresses: [email protected] (W.-d. Zhang), [email protected] (C.-x. Li), [email protected] (Q.-y. Liu), [email protected] (Y.-y. Hu), [email protected] (Y. Cao), [email protected] (J.-h. Huang). 1 Tel.: +86 20 87343217; fax: +86 20 87343392. 2 Tel.: +86 20 81332243; fax: +86 20 81332702. 0720-048X/$ – see front matter © 2010 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.ejrad.2010.06.046
A desmoplastic small round cell tumor (DSRCT) is a malignant pathologic entity with a mesothelial origin. It was first described by Gerald and Rosai in 1989 [1]. In 1991, it was classified as a pathologic entity that primarily occurs in adolescents and young adults [2]. To the best of our knowledge, less than 60 cases of abdominopelvic DSRCT have been reported in the radiological literature [3–12]. Reports on DSRCT are often characterized using computed tomography (CT) findings, whereas only a few cases have been characterized using dynamic enhancement CT scans, magnetic resonance imaging (MRI), or fluorodeoxyglucose-positron
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emission tomography (FDG-PET)/CT imaging findings [10–13]. Herein, we retrospectively reviewed the CT, MR, and FDG-PET/CT imaging findings of 7 cases with abdominopelvic DSRCT and correlated them with the histopathologic characteristics. 1. Materials and methods We searched our hospital database and identified patients who were treated at our hospital between January 2000 and October 2009. In all, 7 patients with DSRCT located in the abdominopelvis were included in this study. An institutional review board exemption and a waiver of the requirement for written informed consent were obtained to perform this retrospective study. Of the 7 patients, 5 had undergone thoracic, abdominal, and pelvic computed tomography (CT), 2 of which were also examined with FDG-PET/CT imaging and 2 had undergone MRI. CT imaging was performed using a Brilliance TM16 (Philips Medical Systems, Best, The Netherlands) helical scanner. The scan parameters were as follows: 5-mm slice thickness reconstructions, 23-cm field of view, 120-kV voltage, 200–300 mA current, and 256 × 256 matrix. All 5 patients had undergone unenhanced and contrast-enhanced CT scanning. An intravenous bolus dose of 100 ml of a nonionic iodinated contrast agent (iopromide; Ultravist; Schering) was administered at a rate of 2.5 mL/s for the patients who underwent contrast-enhanced CT scanning. Abdominal and pelvis contrast-enhanced CT scans were obtained at 30 s, 60 s after the contrast agent injection. In the other 2 cases, additional abdominal and pelvis delayed enhancement scans were performed at 540 s after the injection. MRI was performed using a 1.5 T MRI unit (Gyroscan Intera; Philips Medical Systems, Best, The Netherlands) and a body coil (Philips Medical Systems, Best, The Netherlands). The abdominal MRI protocol included unenhanced axial and coronal T1-weighted sequences; axial T2-weighted sequences; and contrast-enhanced axial, and coronal T1-weighted sequences. The pelvic MRI protocol included unenhanced axial and coronal T1-weighted sequences; axial and sagittal T2-weighted sequences; and contrast-enhanced axial, sagittal, and coronal T1-weighted sequences. The sequence parameters for these sequences were as follows: T1-weighted fast-field echo (FFE) sequence (TR/TE, 174–291/4.6 ms; slice thickness, 8.0 mm; field of view, 380–520 mm; matrix scan, 256 × 256), T2-weighted turbo-spin echo sequence (TR/TE, 1600–3500/90 ms; slice thickness, 5.0 mm; field of view, 300–380 mm; matrix scan, 256 × 256). An intravenous dose of 0.1–0.2 mmol/kg of contrast agent (Gadolinium-DTPA, magnevist; Schering) had been administered to the patients undergoing contrast-enhanced MR scanning. FDG-PET/CT imaging was performed using a dedicated PET/CT system (Discovery ST-16; General Electric Company). The patients were instructed to fast for 6 h prior to being injected with 18FFDG. Blood glucose was measured before the injection of the tracer to ensure that the glucose levels were <8.1 mmol/L. Insulin was injected subcutaneously if necessary. We injected 18F-FDG (4.4–7.4 MBq/kg) intravenously, and the patients were requested to lie comfortably in a dark room for 45–60 min and were instructed to urinate just before PET/CT imaging. The patients were scanned from the calva to the middle part of the femur, lying in a supine position. CT was performed prior to PET, and the resulting data were used to generate an attenuation correction map for PET. PET images were reconstructed with a slice thickness of 3.75 mm using the ordered-subsets expectation maximization iterative image reconstruction method. PET, CT, and fused PET/CT images were generated for review on a Xeleris computer workstation. Two experienced radiologists reviewed the CT, MR, and FDGPET/CT image characteristics of each lesion, which included the location, shape, size, number, edge, and attenuation or intensity of the unenhanced and contrast-enhanced lesions. In the unenhanced
CT and MR images, attenuation or intensity was classified as low, moderate, or high with respect to the adjacent tissues. Conversely, on contrast-enhanced CT or MR images, the degree of enhancement was classified as no, mild, moderate, or marked enhancement. The CT and MRI findings were used to compare the imaging and gross pathological features of the lesions. Four patients underwent debulk surgery, and 3 patients underwent an ultrasound-guided core-needle biopsy. The histological techniques included routine hematoxylin and eosin (H&E) staining and immunohistochemical evaluation. All the pathology specimens were retrospectively reviewed by a pathologist. The macroscopic appearances of 5 resected tumors were analyzed; the shape, size, number, edge, and capsule wall characteristics of the tumors were analyzed. Immunohistochemical analysis included staining for CD99, neuron-specific enolase (NSE), cytokeratin (CK), epithelial membrane antigen (EMA), desmin, vimentin, and muscle-specific actin (HHF35). 2. Results 2.1. Clinical data The study group consisted of 7 men with a mean age of 27 years (range, 22–31 years). Of the 7 patients, 3 presented with abdominal pain, abdominal distention, and abdominal masses, 2 were admitted for an unexpected abdominal mass, 1 presented with an anterior abdominal wall tubercle, and 1 presented with constipation. The laboratory test results of all patients were unremarkable. 2.2. Imaging findings Multiple large masses in the abdominopelvis were found in 6 cases, and a mass in the pelvis was found in 1 case. The largest mass was found in the pelvis in 6 cases and in the mesentery in 1 case; all cases had no definite organ origin for all the large masses. The dimensions of the largest mass were 13 cm × 12 cm × 15 cm and those of the smallest mass were 6 cm × 6 cm × 5 cm. Unenhanced CT images showed multiple soft tissue masses with patchy foci of hypodense areas in 5 cases. Foci of punctuate calcification were observed in 3 cases. Contrast-enhanced CT images showed a mild heterogeneous enhancement with patchy foci of necrosis on arterial phase images (Fig. 1). There was no prolonged, delayed enhancement or washout on portal or delayed phase images. MR T1-weighted images revealed lesions with mild hypointense and patchy hypointense areas in 2 cases, and lesions with patchy hyperintense areas in 1 case. T2-weighted images showed lesions with mixed isointense and hyperintense areas in 1 case and lesions with mixed hypointense, isointense, and hyperintense areas in another. Contrast-enhanced T1-weighted images showed mild heterogeneous enhancement (Fig. 2). Multiple peritoneal seeding was observed in 3 cases. Peritoneal effusions were observed in 3 cases, of which 2 were minimal and 1 was maximal. Small pleural effusions were observed in 2 cases. Lymphadenopathy was observed in the mesenterium (n = 1), retroperitoneum (n = 3), ilium (n = 2), and inguinal canal (n = 1) in 4 cases. Parenchymal hepatic metastasis and serosal hepatic tumor implants from intraperitoneal spread were observed in 2 cases. 2.3. FDG-PET/CT imaging FDG-PET/CT showed multiple nodular foci of increased metabolic activity in the abdominopelvic masses, in the hepatic and right ilium in 1 case and foci of increased metabolic activity in the pelvic mass in another (Fig. 3). The standardized uptake value (SUV)max values for all lesions ranged from 5.2 to 12.7.
W.-d. Zhang et al. / European Journal of Radiology 80 (2011) 269–273
Fig. 1. A 28-year-old male with abdominopelvic desmoplastic small round cell tumor. (A) Contrast-enhanced computed tomography (CT) image shows a round retrovesical, ill-defined heterogeneous mass with patchy of necrosis. (B) Contrastenhanced CT image shows multiple peritoneal seeding and encapsulated ascites. (C) Contrast-enhanced CT image shows multiple parenchymal hepatic metastases and serosal hepatic tumor implants from the intraperitoneal spread.
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Fig. 2. A 22-year-old male with abdominopelvic desmoplastic small round cell tumor. (A) The dominant tumor shows an irregular, ill-defined, mild hypointense lesion with patchy hyperintense areas on axial T1-weighted image. An external iliac lymphadenopathy is present. (B) The dominant tumor shows mixed hypointense, isointense, and hyperintense areas on axial T2-weighted image. (C) The dominant tumor shows mildly heterogeneous enhancement on contrast-enhanced axial T1weighted image.
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Fig. 3. A 26-year-old male with abdominopelvic desmoplastic small round cell tumor. The retrovesical tumor shows punctuated calcification on the computed tomography (CT) image and foci with increased metabolic activity on the positron emission tomography (PET)/CT fusion image. The standardized uptake value (SUV)max value of this lesion is 12.7.
2.4. Microscopy and immunohistochemistry All the resected tumors were not encapsulated. The cut surfaces were tan white or grayish white in color. Patchy cystic areas were observed in all tumors, and patchy hemorrhages were observed in 2 cases. Microscopically, the tumor consisted of nests or small clumps of cells surrounded by a desmoplastic stroma. The tumor cells were frequently small to medium in size and round or oval shaped with a thin cytoplasm and round to oval hyperchromatic nuclei (Fig. 4). The degree of cellularity varied for each tumor and was inversely related to the desmoplastic stroma. Immunohistochemical examination revealed that 6 cases were positive for NSE, CK, EMA, desmin, and vimentin, 4 cases were positive for CD99, and all 7 cases were negative for HHF35. 3. Discussion Fig. 4. Photomicrograph of the histopathological specimen indicates that the tumor consists of nests or small clumps of cells surrounded by a desmoplastic stroma (hematoxylin and eosin (H&E) staining, original magnification 200×).
DSRCTs are rare tumors that often originate from the mesothelium, and belong to the small round cell tumor family that includes primitive neuroectodermal tumors, Ewing’s sarcoma, lymphoma,
W.-d. Zhang et al. / European Journal of Radiology 80 (2011) 269–273
neuroblastoma, rhabdomyosarcoma, and anaplastic synovial sarcoma. Because DSRCT simultaneously demonstrate mesenchymal, epithelial, and neural differentiation, immunohistochemistry can differentiate it from other small round cell tumors [2,14,15]. DSRCT mainly occur in adolescents and young male adults. The male/female ratio was 5:1 [2]. The symptoms of abdominopelvic DSRCT patients are frequently abdominal pain and a palpable mass with no specific manifestation [2]. In our series, all 7 cases were young men, the average age was 27 years, and no specific symptoms were observed. Due to its aggressive nature, abdominopelvic DSRCT often develop into bulky, multiple peritoneal masses that displace the neighboring organs [3–12]. The most common lesion site was the pelvis, the other common sites included the retroperitoneal space, omentum, and mesentery [2]. In our series, all of the lesions involved the pelvis and the largest mass was found in the pelvis in 6 cases. Abdominopelvic DSRCT often appear as multiple soft tissue masses with patchy hypodense foci on unenhanced CT images and with mild heterogeneous enhancement on contrast-enhanced CT images [3–10]. These hypodense areas reflect hemorrhagic tumor necrosis [3,5,8]. The imaging findings and pathological features of the 5 cases in our series were similar to those of the previous reports. In two cases of our series, the solid components demonstrated mild enhancement on arterial phase images, without any prolonged enhancement or washout on portal and delayed phase images. We speculated that this may be caused by densely packed cells and desmoplastic stroma. Abdominopelvic DSRCT often appear as lesions with heterogeneous isointense or hypointense areas on T1-weighted MR images, heterogeneous hyperintense on T2-weighted MR images, and heterogeneous enhancement on contrast-enhanced T1-weighted images [11]. However, the relatively hypointense nature of solid components on T2-weighted MR images was also reported that was caused by densely packed cells and the desmoplastic response [12]. In our series, 1 case demonstrated nodular hypointense lesions on T2-weighted and relatively mild enhancement on contrastenhanced T1-weighted images, which reflect densely desmoplastic tissue. Fluid–fluid levels on T2-weighted MR images and increases in the signal intensity on T1-weighted MR images reflected the presence of hemorrhagic tumor necrosis [11]. One of our cases demonstrated multiple lesions with patchy mild hyperintensity on T1-weighted MR images, which also reflected the presence of hemorrhage that was confirmed by histopathology. Two previous studies reported conflicting data regarding the presence of calcification in abdominopelvic DSRCT [8,9]. In our series, 3 cases showed foci of punctate calcification, indicating that calcification is a relatively common radiological finding in abdominopelvic DSRCT. Peritoneal effusions, peritoneal seeding, and lymphadenopathy are common associated findings in abdominopelvic DSRCT [5,8,9]. In our series, 3 cases showed peritoneal effusions, 4 cases had mesenteric, retroperitoneal space, iliac, and inguinal lymphadenopathy, and 3 cases showed multiple peritoneal seeding and serosal hepatic tumor seeding. Hepatic is the main organ of metastasis of abdominopelvic DSRCT [11]. In our series, 2 cases demonstrated hepatic metastases and 1 case demonstrated bone metastasis. FDG-PET/CT imaging can provide useful information on the tumor stage and identify occult lesions that cannot be obtained using CT or MRI. In one case of our series, FDG-PET/CT imaging showed nodular foci with increased metabolic activity in the
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abdominopelvis corresponding to the CT imaging and 1 additional metastasis in the right ilium that was not detected using CT imaging. The SUVmax values of the tumors ranged from 5.2 to 12.7, reflecting their aggressive nature. The prognosis for DSRCT is poor [16]. Bellah et al. reported a median survival of only 23 months [9]. In our series, 2 patients died of metastasis 12 months and 21 months after treatment, respectively. The other 5 cases were stable during the 6–60-month follow-up period. 4. Conclusion Radiological findings of DSRCT include multiple heterogeneous density/intensity masses without an organ origin. Other associated findings include peritoneal seeding, peritoneal effusion, hepatic metastasis, and retroperitoneal lymphadenopathy. DSRCT should be considered in the differential diagnosis of regional tumors in adolescents and young adults. FDG-PET/CT imaging can provide additional information with respect to the stage of the tumor. Conflict of interest Authors stated no financial relationship to disclose. References [1] Gerald WL, Rosai J. Case 2. Desmoplastic small cell tumor with divergent differentiation. Pediatr Pathol 1989;9(2):177–83. [2] Gerald WL, Miller HK, Battifora H, et al. Intra-abdominal desmoplastic small round-cell tumor. Report of 19 cases of a distinctive type of high-grade polyphenotypic malignancy affecting young individuals. Am J Surg Pathol 1991;15(6):499–513. [3] Outwater E, Schiebler ML, Brooks JJ. Intraabdominal desmoplastic small cell tumor: CT and MR findings. J Comput Assist Tomogr 1992;16(3):429–32. [4] Dao HN, Dachman AH. CT findings of regression in intraabdominal desmoplastic small-cell tumor. Clin Imaging 1995;19(4):244–6. [5] Pickhardt PJ, Fisher AJ, Balfe DM, et al. Desmoplastic small round cell tumor of the abdomen: radiologic–histopathologic correlation. Radiology 1999;210(3):633–8. [6] Sabaté JM, Torrubia S, Roson N, et al. Intra-abdominal desmoplastic small round-cell tumor: a rare cause of peritoneal malignancy in young people. Eur Radiol 2000;10(5):817–9. [7] Mainenti PP, Romano L, Contegiacomo A, et al. Rare diffuse peritoneal malignant neoplasms: CT findings in two cases. Abdom Imaging 2003;28(6):827–30. [8] Chouli M, Viala J, Dromain C, et al. Intra-abdominal desmoplastic small round cell tumors: CT findings and clinicopathological correlations in 13 cases. Eur J Radiol 2005;54(3):438–42. [9] Bellah R, Suzuki-Bordalo L, Brecher E, et al. Desmoplastic small round cell tumor in the abdomen and pelvis: report of CT findings in 11 affected children and young adults. AJR Am J Roentgenol 2005;184(6):1910–4. [10] Kim JH, Goo HW, Yoon CH. Intra-abdominal desmoplastic small roundcell tumour: multiphase CT findings in two children. Pediatr Radiol 2003;33(6):418–21. [11] Tateishi U, Hasegawa T, Kusumoto M, et al. Desmoplastic small round cell tumor: imaging findings associated with clinicopathologic features. J Comput Assist Tomogr 2002;26(4):579–83. [12] Gorospe L, Gómez T, González LM, et al. Desmoplastic small round cell tumor of the pelvis: MRI findings with histopathologic correlation. Eur Radiol 2007;17(1):287–8. [13] Pickhardt PJ. F-18 fluorodeoxyglucose positron emission tomographic imaging in desmoplastic small round cell tumor of the abdomen. Clin Nucl Med 1999;24(9):693–4. [14] Gerald WL, Ladanyi M, de Alava E, et al. Clinical, pathologic, and molecular spectrum of tumors associated with t(11;22)(p13;q12): desmoplastic small round-cell tumor and its variants. J Clin Oncol 1998;16(9):3028–36. [15] Lae ME, Roche PC, Jin L, et al. Desmoplastic small round cell tumor: a clinicopathologic, immunohistochemical, and molecular study of 32 tumors. Am J Surg Pathol 2002;26(7):823–35. [16] Stuart-Buttle CE, Smart CJ, Pritchard S, et al. Desmoplastic small round cell tumour: a review of literature and treatment options. Surg Oncol 2008;17(2):107–12.
Contents lists available at ScienceDirect
European Journal of Radiology journal homepage: www.elsevier.com/locate/ejrad
CT, MRI, and FDG-PET/CT imaging findings of abdominopelvic desmoplastic small round cell tumors: Correlation with histopathologic findings Wei-dong Zhang a,b,1, Chuan-xing Li a,b,1, Qing-yu Liu c,2, Ying-ying Hu a,b,1, Yun Cao a,d,1, Jin-hua Huang a,b,∗ a
State Key Laboratory of Oncology in South China, 651 Dongfengdong Road, Guangzhou, Guangdong 510060, PR China Department of Radiology, Cancer Center, Sun Yat-sen University, Guangzhou, Guangdong 510060, PR China c Department of Radiology, No. 2 Affiliated Hospital, 107 Yanjiangxi Road, Sun Yat-sen University, Guangzhou, Guangdong 510120, PR China d Department of Pathology, Cancer Center, Sun Yat-sen University, Guangzhou, Guangdong 510060, PR China b
a r t i c l e
i n f o
Article history: Received 5 May 2010 Received in revised form 23 June 2010 Accepted 25 June 2010 Keywords: Desmoplastic small round cell tumor Computed tomography Magnetic resonance imaging FDG-PET/CT imaging Pathology
a b s t r a c t Objective: To analyze computed tomography (CT), magnetic resonance imaging (MRI), and fluorodeoxyglucose-positron emission tomography (FDG-PET)/CT imaging features of abdominopelvic desmoplastic small round cell tumor (DSRCT) and to improve the diagnostic efficacy of these techniques for the detection of such tumor. Methods: We retrospectively analyzed 7 cases of abdominopelvic DSRCT confirmed by histopathologic analysis. Among the 7 patients, 5 patients had undergone CT scanning, 2 of which were also examined with FDG-PET/CT imaging, and 2 had undergone MRI. Unenhanced and contrast-enhanced examinations were performed in all patients, and 2 patients had also undergone dynamic CT contrast-enhanced examinations. Image characteristics, such as shape, size, number, edge, attenuation, and intensity of each lesion before and after contrast enhancement were analyzed and compared with the pathomorphology of the tumors. Results: Multiple large masses in the abdominopelvis were detected in 6 cases, and a large mass in the pelvis was detected in 1 case. Six cases showed largest mass in pelvis, and 1 case in mesentery. None of the masses had a definite organ origin. CT showed soft tissue masses with patchy foci of hypodense areas. MR T1-weighted images revealed lesions with mild hypointense areas and patchy hypointense areas in 2 cases and lesions with patchy hyperintense areas in 1 case. T2-weighted images showed lesions with mixed isointense and hyperintense areas in 1 case and lesions with mixed hypointense, isointense, and hyperintense areas in another. Contrast-enhanced CT and T1-weighted images showed mildly heterogeneous enhancement of the lesions. Other associated findings included peritoneal seeding (n = 3), peritoneal effusions (n = 3), hepatic metastasis (n = 2), bone metastasis (n = 1), and mesenteric and retroperitoneal lymphadenopathy (n = 4). FDG-PET/CT showed multiple nodular foci of increased metabolic activity in the abdominopelvic masses, in the hepatic and right ilium in 1 case and foci of increased metabolic activity in the pelvic mass in another. Conclusion: Radiological findings of DSRCT include multiple masses with heterogeneous density/intensity and without an organ origin. Other common associated findings include peritoneal seeding, peritoneal effusion, hepatic metastasis, and retroperitoneal lymphadenopathy. DSRCT should be considered in the differential diagnosis of regional tumors in adolescents and young adults. FDG-PET/CT can provide additional information on the stage of the tumor. © 2010 Elsevier Ireland Ltd. All rights reserved.
∗ Corresponding author at: State Key Laboratory of Oncology in South China, 651 Dongfengdong Road, Guangzhou, Guangdong 510060, PR China. Tel.: +86 20 87343217; fax: +86 20 87343392. E-mail addresses: [email protected] (W.-d. Zhang), [email protected] (C.-x. Li), [email protected] (Q.-y. Liu), [email protected] (Y.-y. Hu), [email protected] (Y. Cao), [email protected] (J.-h. Huang). 1 Tel.: +86 20 87343217; fax: +86 20 87343392. 2 Tel.: +86 20 81332243; fax: +86 20 81332702. 0720-048X/$ – see front matter © 2010 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.ejrad.2010.06.046
A desmoplastic small round cell tumor (DSRCT) is a malignant pathologic entity with a mesothelial origin. It was first described by Gerald and Rosai in 1989 [1]. In 1991, it was classified as a pathologic entity that primarily occurs in adolescents and young adults [2]. To the best of our knowledge, less than 60 cases of abdominopelvic DSRCT have been reported in the radiological literature [3–12]. Reports on DSRCT are often characterized using computed tomography (CT) findings, whereas only a few cases have been characterized using dynamic enhancement CT scans, magnetic resonance imaging (MRI), or fluorodeoxyglucose-positron
270
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emission tomography (FDG-PET)/CT imaging findings [10–13]. Herein, we retrospectively reviewed the CT, MR, and FDG-PET/CT imaging findings of 7 cases with abdominopelvic DSRCT and correlated them with the histopathologic characteristics. 1. Materials and methods We searched our hospital database and identified patients who were treated at our hospital between January 2000 and October 2009. In all, 7 patients with DSRCT located in the abdominopelvis were included in this study. An institutional review board exemption and a waiver of the requirement for written informed consent were obtained to perform this retrospective study. Of the 7 patients, 5 had undergone thoracic, abdominal, and pelvic computed tomography (CT), 2 of which were also examined with FDG-PET/CT imaging and 2 had undergone MRI. CT imaging was performed using a Brilliance TM16 (Philips Medical Systems, Best, The Netherlands) helical scanner. The scan parameters were as follows: 5-mm slice thickness reconstructions, 23-cm field of view, 120-kV voltage, 200–300 mA current, and 256 × 256 matrix. All 5 patients had undergone unenhanced and contrast-enhanced CT scanning. An intravenous bolus dose of 100 ml of a nonionic iodinated contrast agent (iopromide; Ultravist; Schering) was administered at a rate of 2.5 mL/s for the patients who underwent contrast-enhanced CT scanning. Abdominal and pelvis contrast-enhanced CT scans were obtained at 30 s, 60 s after the contrast agent injection. In the other 2 cases, additional abdominal and pelvis delayed enhancement scans were performed at 540 s after the injection. MRI was performed using a 1.5 T MRI unit (Gyroscan Intera; Philips Medical Systems, Best, The Netherlands) and a body coil (Philips Medical Systems, Best, The Netherlands). The abdominal MRI protocol included unenhanced axial and coronal T1-weighted sequences; axial T2-weighted sequences; and contrast-enhanced axial, and coronal T1-weighted sequences. The pelvic MRI protocol included unenhanced axial and coronal T1-weighted sequences; axial and sagittal T2-weighted sequences; and contrast-enhanced axial, sagittal, and coronal T1-weighted sequences. The sequence parameters for these sequences were as follows: T1-weighted fast-field echo (FFE) sequence (TR/TE, 174–291/4.6 ms; slice thickness, 8.0 mm; field of view, 380–520 mm; matrix scan, 256 × 256), T2-weighted turbo-spin echo sequence (TR/TE, 1600–3500/90 ms; slice thickness, 5.0 mm; field of view, 300–380 mm; matrix scan, 256 × 256). An intravenous dose of 0.1–0.2 mmol/kg of contrast agent (Gadolinium-DTPA, magnevist; Schering) had been administered to the patients undergoing contrast-enhanced MR scanning. FDG-PET/CT imaging was performed using a dedicated PET/CT system (Discovery ST-16; General Electric Company). The patients were instructed to fast for 6 h prior to being injected with 18FFDG. Blood glucose was measured before the injection of the tracer to ensure that the glucose levels were <8.1 mmol/L. Insulin was injected subcutaneously if necessary. We injected 18F-FDG (4.4–7.4 MBq/kg) intravenously, and the patients were requested to lie comfortably in a dark room for 45–60 min and were instructed to urinate just before PET/CT imaging. The patients were scanned from the calva to the middle part of the femur, lying in a supine position. CT was performed prior to PET, and the resulting data were used to generate an attenuation correction map for PET. PET images were reconstructed with a slice thickness of 3.75 mm using the ordered-subsets expectation maximization iterative image reconstruction method. PET, CT, and fused PET/CT images were generated for review on a Xeleris computer workstation. Two experienced radiologists reviewed the CT, MR, and FDGPET/CT image characteristics of each lesion, which included the location, shape, size, number, edge, and attenuation or intensity of the unenhanced and contrast-enhanced lesions. In the unenhanced
CT and MR images, attenuation or intensity was classified as low, moderate, or high with respect to the adjacent tissues. Conversely, on contrast-enhanced CT or MR images, the degree of enhancement was classified as no, mild, moderate, or marked enhancement. The CT and MRI findings were used to compare the imaging and gross pathological features of the lesions. Four patients underwent debulk surgery, and 3 patients underwent an ultrasound-guided core-needle biopsy. The histological techniques included routine hematoxylin and eosin (H&E) staining and immunohistochemical evaluation. All the pathology specimens were retrospectively reviewed by a pathologist. The macroscopic appearances of 5 resected tumors were analyzed; the shape, size, number, edge, and capsule wall characteristics of the tumors were analyzed. Immunohistochemical analysis included staining for CD99, neuron-specific enolase (NSE), cytokeratin (CK), epithelial membrane antigen (EMA), desmin, vimentin, and muscle-specific actin (HHF35). 2. Results 2.1. Clinical data The study group consisted of 7 men with a mean age of 27 years (range, 22–31 years). Of the 7 patients, 3 presented with abdominal pain, abdominal distention, and abdominal masses, 2 were admitted for an unexpected abdominal mass, 1 presented with an anterior abdominal wall tubercle, and 1 presented with constipation. The laboratory test results of all patients were unremarkable. 2.2. Imaging findings Multiple large masses in the abdominopelvis were found in 6 cases, and a mass in the pelvis was found in 1 case. The largest mass was found in the pelvis in 6 cases and in the mesentery in 1 case; all cases had no definite organ origin for all the large masses. The dimensions of the largest mass were 13 cm × 12 cm × 15 cm and those of the smallest mass were 6 cm × 6 cm × 5 cm. Unenhanced CT images showed multiple soft tissue masses with patchy foci of hypodense areas in 5 cases. Foci of punctuate calcification were observed in 3 cases. Contrast-enhanced CT images showed a mild heterogeneous enhancement with patchy foci of necrosis on arterial phase images (Fig. 1). There was no prolonged, delayed enhancement or washout on portal or delayed phase images. MR T1-weighted images revealed lesions with mild hypointense and patchy hypointense areas in 2 cases, and lesions with patchy hyperintense areas in 1 case. T2-weighted images showed lesions with mixed isointense and hyperintense areas in 1 case and lesions with mixed hypointense, isointense, and hyperintense areas in another. Contrast-enhanced T1-weighted images showed mild heterogeneous enhancement (Fig. 2). Multiple peritoneal seeding was observed in 3 cases. Peritoneal effusions were observed in 3 cases, of which 2 were minimal and 1 was maximal. Small pleural effusions were observed in 2 cases. Lymphadenopathy was observed in the mesenterium (n = 1), retroperitoneum (n = 3), ilium (n = 2), and inguinal canal (n = 1) in 4 cases. Parenchymal hepatic metastasis and serosal hepatic tumor implants from intraperitoneal spread were observed in 2 cases. 2.3. FDG-PET/CT imaging FDG-PET/CT showed multiple nodular foci of increased metabolic activity in the abdominopelvic masses, in the hepatic and right ilium in 1 case and foci of increased metabolic activity in the pelvic mass in another (Fig. 3). The standardized uptake value (SUV)max values for all lesions ranged from 5.2 to 12.7.
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Fig. 1. A 28-year-old male with abdominopelvic desmoplastic small round cell tumor. (A) Contrast-enhanced computed tomography (CT) image shows a round retrovesical, ill-defined heterogeneous mass with patchy of necrosis. (B) Contrastenhanced CT image shows multiple peritoneal seeding and encapsulated ascites. (C) Contrast-enhanced CT image shows multiple parenchymal hepatic metastases and serosal hepatic tumor implants from the intraperitoneal spread.
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Fig. 2. A 22-year-old male with abdominopelvic desmoplastic small round cell tumor. (A) The dominant tumor shows an irregular, ill-defined, mild hypointense lesion with patchy hyperintense areas on axial T1-weighted image. An external iliac lymphadenopathy is present. (B) The dominant tumor shows mixed hypointense, isointense, and hyperintense areas on axial T2-weighted image. (C) The dominant tumor shows mildly heterogeneous enhancement on contrast-enhanced axial T1weighted image.
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Fig. 3. A 26-year-old male with abdominopelvic desmoplastic small round cell tumor. The retrovesical tumor shows punctuated calcification on the computed tomography (CT) image and foci with increased metabolic activity on the positron emission tomography (PET)/CT fusion image. The standardized uptake value (SUV)max value of this lesion is 12.7.
2.4. Microscopy and immunohistochemistry All the resected tumors were not encapsulated. The cut surfaces were tan white or grayish white in color. Patchy cystic areas were observed in all tumors, and patchy hemorrhages were observed in 2 cases. Microscopically, the tumor consisted of nests or small clumps of cells surrounded by a desmoplastic stroma. The tumor cells were frequently small to medium in size and round or oval shaped with a thin cytoplasm and round to oval hyperchromatic nuclei (Fig. 4). The degree of cellularity varied for each tumor and was inversely related to the desmoplastic stroma. Immunohistochemical examination revealed that 6 cases were positive for NSE, CK, EMA, desmin, and vimentin, 4 cases were positive for CD99, and all 7 cases were negative for HHF35. 3. Discussion Fig. 4. Photomicrograph of the histopathological specimen indicates that the tumor consists of nests or small clumps of cells surrounded by a desmoplastic stroma (hematoxylin and eosin (H&E) staining, original magnification 200×).
DSRCTs are rare tumors that often originate from the mesothelium, and belong to the small round cell tumor family that includes primitive neuroectodermal tumors, Ewing’s sarcoma, lymphoma,
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neuroblastoma, rhabdomyosarcoma, and anaplastic synovial sarcoma. Because DSRCT simultaneously demonstrate mesenchymal, epithelial, and neural differentiation, immunohistochemistry can differentiate it from other small round cell tumors [2,14,15]. DSRCT mainly occur in adolescents and young male adults. The male/female ratio was 5:1 [2]. The symptoms of abdominopelvic DSRCT patients are frequently abdominal pain and a palpable mass with no specific manifestation [2]. In our series, all 7 cases were young men, the average age was 27 years, and no specific symptoms were observed. Due to its aggressive nature, abdominopelvic DSRCT often develop into bulky, multiple peritoneal masses that displace the neighboring organs [3–12]. The most common lesion site was the pelvis, the other common sites included the retroperitoneal space, omentum, and mesentery [2]. In our series, all of the lesions involved the pelvis and the largest mass was found in the pelvis in 6 cases. Abdominopelvic DSRCT often appear as multiple soft tissue masses with patchy hypodense foci on unenhanced CT images and with mild heterogeneous enhancement on contrast-enhanced CT images [3–10]. These hypodense areas reflect hemorrhagic tumor necrosis [3,5,8]. The imaging findings and pathological features of the 5 cases in our series were similar to those of the previous reports. In two cases of our series, the solid components demonstrated mild enhancement on arterial phase images, without any prolonged enhancement or washout on portal and delayed phase images. We speculated that this may be caused by densely packed cells and desmoplastic stroma. Abdominopelvic DSRCT often appear as lesions with heterogeneous isointense or hypointense areas on T1-weighted MR images, heterogeneous hyperintense on T2-weighted MR images, and heterogeneous enhancement on contrast-enhanced T1-weighted images [11]. However, the relatively hypointense nature of solid components on T2-weighted MR images was also reported that was caused by densely packed cells and the desmoplastic response [12]. In our series, 1 case demonstrated nodular hypointense lesions on T2-weighted and relatively mild enhancement on contrastenhanced T1-weighted images, which reflect densely desmoplastic tissue. Fluid–fluid levels on T2-weighted MR images and increases in the signal intensity on T1-weighted MR images reflected the presence of hemorrhagic tumor necrosis [11]. One of our cases demonstrated multiple lesions with patchy mild hyperintensity on T1-weighted MR images, which also reflected the presence of hemorrhage that was confirmed by histopathology. Two previous studies reported conflicting data regarding the presence of calcification in abdominopelvic DSRCT [8,9]. In our series, 3 cases showed foci of punctate calcification, indicating that calcification is a relatively common radiological finding in abdominopelvic DSRCT. Peritoneal effusions, peritoneal seeding, and lymphadenopathy are common associated findings in abdominopelvic DSRCT [5,8,9]. In our series, 3 cases showed peritoneal effusions, 4 cases had mesenteric, retroperitoneal space, iliac, and inguinal lymphadenopathy, and 3 cases showed multiple peritoneal seeding and serosal hepatic tumor seeding. Hepatic is the main organ of metastasis of abdominopelvic DSRCT [11]. In our series, 2 cases demonstrated hepatic metastases and 1 case demonstrated bone metastasis. FDG-PET/CT imaging can provide useful information on the tumor stage and identify occult lesions that cannot be obtained using CT or MRI. In one case of our series, FDG-PET/CT imaging showed nodular foci with increased metabolic activity in the
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abdominopelvis corresponding to the CT imaging and 1 additional metastasis in the right ilium that was not detected using CT imaging. The SUVmax values of the tumors ranged from 5.2 to 12.7, reflecting their aggressive nature. The prognosis for DSRCT is poor [16]. Bellah et al. reported a median survival of only 23 months [9]. In our series, 2 patients died of metastasis 12 months and 21 months after treatment, respectively. The other 5 cases were stable during the 6–60-month follow-up period. 4. Conclusion Radiological findings of DSRCT include multiple heterogeneous density/intensity masses without an organ origin. Other associated findings include peritoneal seeding, peritoneal effusion, hepatic metastasis, and retroperitoneal lymphadenopathy. DSRCT should be considered in the differential diagnosis of regional tumors in adolescents and young adults. FDG-PET/CT imaging can provide additional information with respect to the stage of the tumor. Conflict of interest Authors stated no financial relationship to disclose. References [1] Gerald WL, Rosai J. Case 2. Desmoplastic small cell tumor with divergent differentiation. Pediatr Pathol 1989;9(2):177–83. [2] Gerald WL, Miller HK, Battifora H, et al. Intra-abdominal desmoplastic small round-cell tumor. Report of 19 cases of a distinctive type of high-grade polyphenotypic malignancy affecting young individuals. Am J Surg Pathol 1991;15(6):499–513. [3] Outwater E, Schiebler ML, Brooks JJ. Intraabdominal desmoplastic small cell tumor: CT and MR findings. J Comput Assist Tomogr 1992;16(3):429–32. [4] Dao HN, Dachman AH. CT findings of regression in intraabdominal desmoplastic small-cell tumor. Clin Imaging 1995;19(4):244–6. [5] Pickhardt PJ, Fisher AJ, Balfe DM, et al. Desmoplastic small round cell tumor of the abdomen: radiologic–histopathologic correlation. Radiology 1999;210(3):633–8. [6] Sabaté JM, Torrubia S, Roson N, et al. Intra-abdominal desmoplastic small round-cell tumor: a rare cause of peritoneal malignancy in young people. Eur Radiol 2000;10(5):817–9. [7] Mainenti PP, Romano L, Contegiacomo A, et al. Rare diffuse peritoneal malignant neoplasms: CT findings in two cases. Abdom Imaging 2003;28(6):827–30. [8] Chouli M, Viala J, Dromain C, et al. Intra-abdominal desmoplastic small round cell tumors: CT findings and clinicopathological correlations in 13 cases. Eur J Radiol 2005;54(3):438–42. [9] Bellah R, Suzuki-Bordalo L, Brecher E, et al. Desmoplastic small round cell tumor in the abdomen and pelvis: report of CT findings in 11 affected children and young adults. AJR Am J Roentgenol 2005;184(6):1910–4. [10] Kim JH, Goo HW, Yoon CH. Intra-abdominal desmoplastic small roundcell tumour: multiphase CT findings in two children. Pediatr Radiol 2003;33(6):418–21. [11] Tateishi U, Hasegawa T, Kusumoto M, et al. Desmoplastic small round cell tumor: imaging findings associated with clinicopathologic features. J Comput Assist Tomogr 2002;26(4):579–83. [12] Gorospe L, Gómez T, González LM, et al. Desmoplastic small round cell tumor of the pelvis: MRI findings with histopathologic correlation. Eur Radiol 2007;17(1):287–8. [13] Pickhardt PJ. F-18 fluorodeoxyglucose positron emission tomographic imaging in desmoplastic small round cell tumor of the abdomen. Clin Nucl Med 1999;24(9):693–4. [14] Gerald WL, Ladanyi M, de Alava E, et al. Clinical, pathologic, and molecular spectrum of tumors associated with t(11;22)(p13;q12): desmoplastic small round-cell tumor and its variants. J Clin Oncol 1998;16(9):3028–36. [15] Lae ME, Roche PC, Jin L, et al. Desmoplastic small round cell tumor: a clinicopathologic, immunohistochemical, and molecular study of 32 tumors. Am J Surg Pathol 2002;26(7):823–35. [16] Stuart-Buttle CE, Smart CJ, Pritchard S, et al. Desmoplastic small round cell tumour: a review of literature and treatment options. Surg Oncol 2008;17(2):107–12.