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CT findings
European Journal of Radiology Extra 77 (2011) e39–e42
Contents lists available at ScienceDirect
European Journal of Radiology Extra journal homepage: intl.elsevierhealth.com/journals/ejrex
A case of localized amyloidosis in the mediastinum, CT, MRI, and 18 F-FDG-PET/CT findings Mikako Jinnouchi a , Masamitsu Hatakenaka a,∗ , Hidetake Yabuuchi b , Yoshio Matsuo a , Shunya Sunami a , Takeshi Kamitani a , Masahiro Komori a , Yuko Kitajima c , Nobuhiro Fujita d , Hiroshi Honda a a
Department of Clinical Radiology, Graduate School of Medical Sciences, Kyushu University, 3-1-1, Maidashi, Higashi-ku, Fukuoka 812-8582, Japan Department of Health Sciences, Graduate School of Medical Sciences, Kyushu University, Japan Research Institute for Diseases of the Chest, Graduate School of Medical Sciences, Kyushu University, Japan d Department of Anatomic Pathology, Graduate School of Medical Sciences, Kyushu University, Japan b c
a r t i c l e
i n f o
Article history: Received 22 October 2010 Received in revised form 2 December 2010 Accepted 2 December 2010
Keywords: Localized amyloidosis Mediastinum CT MRI FDG-PET
a b s t r a c t Amyloidosis is a heterogeneous group of diseases characterized by the presence of extracellular deposition of amyloid. We present a case of localized amyloidosis of the middle mediastinum, that was diagnosed by trans-esophageal endoscopic ultrasound (EUS)-guided biopsy, focusing on imaging features of contrast-enhanced CT, MRI including dynamic contrast-enhanced study and DWI, and integrated fluorine-18 fluorodeoxyglucose (18 F-FDG) positron emission tomography (PET)/CT. © 2010 Elsevier Ireland Ltd. All rights reserved.
1. Introduction Amyloidosis is a heterogeneous group of diseases characterized by the presence of extracellular deposition of insoluble, fibrillar, proteinaceous material. Amyloidosis is usually seen in a systemic form, and 10–20% of cases can be localized [1–3]. It can be clinically challenging to differentiate mass-forming localized amyloidosis from neoplastic lesions, but there have been several reports regarding imaging findings of localized amyloidosis. To our knowledge, however, there have been few reports regarding its enhancement pattern on dynamic study, and there have been no reports on DWI which would provide somewhat characteristic findings. We present a case of localized amyloidosis of the middle mediastinum, focusing on imaging characteristics. 2. Case A mass lesion of the left hilum was detected on a routine chest radiograph of a 38-year-old originally healthy man. Contrastenhanced CT performed at a neighboring hospital revealed a lobulated mass spreading from the middle mediastinum to the
∗ Corresponding author. Tel.: +81 92 642 5695; fax: +81 92 642 5708. E-mail address: [email protected] (M. Hatakenaka). 1571-4675/$ – see front matter © 2010 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.ejrex.2010.12.003
left hilum without obvious compression of surrounding structures accompanying coarse calcifications and inhomogeneous internal enhancement (Fig. 1). Trans-bronchial lung biopsy did not lead to a definite diagnosis, and he was referred to our hospital for further investigation. MR examination was performed at our hospital with a 1.5T scanner using a sensitivity-encoding cardiac coil. Precontrast axial T1- and T2-weighted spin-echo sequences were obtained at first. DWI was performed by using a multisection spin-echo single-shot echo-planar sequence in the axial plane with b values of 0 and 1000 s/mm2 . Thereafter, apparent diffusion coefficient (ADC) maps were generated. For dynamic contrast-enhancement study, gadopentetate dimeglumine (0.2 ml/kg of body weight) was administered intravenously at a rate of 2 ml/s. MR images were sequentially obtained before and every 30 s for 5 min after contrast material administration. One author (M.J.) manually drew regions of interest (ROIs) for signal intensity measurement. Thereafter, we plotted the average signal intensity within the ROI against time, and a time intensity curve (TIC) was constructed. The mass showed slightly higher signal intensity than that of muscle on T1weighted images and inhomogeneous signal intensity including hypo signal intensity on T2-weighted images (Fig. 2). On DWI with a b value of 1000 s/mm2 , the lesion showed relatively high signal intensity, and the mean ADC was 1.0 (×10−3 mm2 /s) (Fig. 3). TIC showed a rapid increase in signal intensity during the early phase
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M. Jinnouchi et al. / European Journal of Radiology Extra 77 (2011) e39–e42
Fig. 1. The contrast-enhanced CT shows an inhomogeneously enhanced mass spreading from the middle mediastinum to the left hilum with coarse calcifications.
Fig. 2. T2-weighted MR image (TR/TE: 1846/100) reveals a mediastinal mass with a heterogeneous low signal intensity.
and washout after the peak. The mass revealed inhomogeneous internal enhancement on delayed images (Fig. 4). 18 F-FDG-PET/CT showed increased uptake of 18 F-FDG corresponding to the mediastinal lesion; the maximal standardized uptake value (SUV) was 4.8 (Fig. 5). For the determination of diagnosis, trans-esophageal EUSguided biopsy was performed. A microscopic view of the specimen (hematoxylin and eosin stain) showed fibrinoid deposition, lymphocyte dominant inflammatory cell infiltration, and eosinophilic acellular material (Fig. 6a). The material was positively stained with Congo-Red stain (Fig. 6b). Immunohistochemically, light
Fig. 4. (a) Axial T1-weighted spin-echo MR image (TR/TE: 923/9.0) obtained 60 s after contrast material administration shows early enhancement. The round cursor marks the ROI selected for signal intensity measurement at dynamic MR imaging. (b) Axial T1-weighted spin-echo MR image (TR/TE: 923/9.0) obtained 300 s after contrast material administration shows a slight washout. (c) TIC shows a rapid peak and washout enhancement pattern.
Fig. 3. DWI (b = 1000 s/mm2 ) shows a mediastinal mass with high signal intensity. The mean ADC was 1.0 (×10−3 mm2 /s).
chains were positive. These histological findings were consistent with AL()-type amyloidosis. Biopsy of the stomach, duodenum, ileum, colon, and rectum did not prove amyloidosis. Bone marrow biopsy revealed normal bone-marrow cells, and he did not have any underlying illness. He was therefore diagnosed as primary localized mediastinal amyloidosis.
M. Jinnouchi et al. / European Journal of Radiology Extra 77 (2011) e39–e42
Fig. 5. The 18 F-FDG-PET shows increased uptake of mediastinal lesion (maximal SUV = 4.8).
18
F-FDG corresponding to the
3. Discussion Amyloidosis is a collection of disease entities that are characterized by the presence of extracellular deposition of insoluble, fibrillar, proteinaceous material with a well-defined -pleated sheet ultrastructure. Clinically, amyloidosis is categorized into two main forms, systemic and localized. Systemic amyloidosis is subclassified into an idiopathic primary form and a secondary or reactive form. Some causes of secondary amyloidosis are plasma cell dyscrasias such as multiple myeloma and chronic inflammatory condition. Amyloidosis is usually seen in a systemic form, and 10–20% of cases can be localized [1,2]. Localized mediastinal amyloidosis is very rare, with only 5 cases having been reported in English literature [3–7], and one of them was a secondary lesion to rheumatoid arthritis [5]. Our case is considered to be the first case of mediastinal amyloidosis in which the diagnosis was made by trans-esophageal EUS-guided biopsy. In four of the six cases (including our case), accompanying calcification was observed on CT [3–5]. Although there have been few reports describing imaging findings [3,4], accompanying calcification is considered to be relatively characteristic [1,3–5,10–12]. This finding is thought to be a result of large amounts of divalent sodium and calcium-bound protein which amyloid fibrils frequently contain [11]. Previously described MR findings of amyloidosis have varied, homo- or inhomogeneous, and hypo to high signal intensity having been observed on both T1- and T2-weighted images [1,2,8–18]. However, hypo signal intensity on T2-weighted images, whether entirely or partially, is considered relatively characteristic [1,10–17]. The exact mechanism of hypo signal intensity on T2-weighted images is uncertain. In some cases it has obviously reflected calcification [1,11], while in other cases it has not. Some hypotheses have been reported. First, protons are fixed in a -pleated sheet and have a long correlation time. Second, pro-
e41
ton density decrease in a -pleated sheet. Third, rapid chemical exchange and spin–spin interactions may occur between the amyloid protein and adjacent water molecules. Fourth, an amyloid microenvironment composed of a heterogeneous micromagnetic mixture of collagen, calcification, and vessels, as well as amyloid fibrils, may cause differences in diamagnetic susceptibility [12]. In addition, various patterns and degrees of enhancement by contrast material have been described on both CT and MRI; no enhancement, homogeneous or inhomogeneous, strong or weak [10,13–17]. However, we found that the majority of amyloidoma showed enhancement of some kind. The mechanism of enhancement is also uncertain. Gean-Marton et al. have reported that remarkable subendothelial deposition of amyloid can be seen histologically within an arteriole, which is indicative of the fragility of vessel [12]. Concerning the dynamic contrast-enhancement study, Asaumi et al. have reported that a case of localized amyloidosis of the tongue exhibited an increase in signal intensity until it reached a plateau, and then a gradual decrease during late and delay phases [13]. They speculated that this pattern might be due to enhancement of the vessels themselves in the mass. It has also been reported that increasing calcification decreased enhancement by contrast material [14]. There has been no literature about DWI findings of amyloidosis. In the present case, relatively low ADC was observed. We speculate that the mechanism for the interruption of diffusion is that a thick, high-viscosity fluid consisting of water, inflammatory cells, and a proteinous matrix causes a marked restriction of water proton mobility. Based on a study investigating the ability of 18 F-FDG PET/CT to distinguish malignant lung tumor from other benign lesions, Quaia et al. have reported a case of amyloidosis diagnosed as malignancy, when they diagnosed a pulmonary nodule/mass as malignancy when SUV > 2.5 [19]. We found another two English reports in which an abnormal uptake of 18 F-FDG to nodular pulmonary amyloidosis was observed, but SUV was not described in the literature [20,21]. In one of these cases, multiple bilateral pulmonary lesions were observed, but only one nodule showed an abnormal uptake of 18 F-FDG, and the rest did not. They reported that whether uptake is observed or not did not depend on nodule size [20]. In these studies, the mechanism of uptake of 18 F-FDG to the lesions of amyloidosis was not discussed. We consider that the chronic inflammatory cell infiltration observed histologically in the present case is somehow related to the uptake mechanism. In some studies, inflammatory cells infiltration has also been histologically observed in the lesions of amyloidosis [3,15]. Amyloidosis might accompany chronic inflammation that could cause abnormal uptake of FDG. In this case, it was difficult to reach a correct diagnosis before biopsy. On CT, the lesion showed a spread from the middle mediastinum to the left hilum and did not show an obvious mass
Fig. 6. (a) Photomicrograph of pathologic specimen of the mediastinal mass obtained in a transesophageal EUS-guided biopsy (Hematoxylin and Eosin stain, high-powerfield) shows fibrinoid deposition, lymphocyte dominant inflammatory cells infiltration, and eosinophilic acellular material. (b) The material was positively stained with Congo-Red stain.
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M. Jinnouchi et al. / European Journal of Radiology Extra 77 (2011) e39–e42
effect. This finding made us imagine a relatively soft mass. However, hypointensity on T2WI, strong and rapid enhancement on dynamic contrast-enhancement MR images, and high signal intensity on DWI made us imagine a solid mass with high cellularity and vascularity. We could not find a diagnosis satisfying these findings. Hemangioma could be an appropriate diagnosis for a soft and hypervascular mass with calcification, but low signal intensity on T2-weighted images did not accord with hemangioma. Malignant lymphoma could also be a diagnosis for a soft mass with low signal intensity on T2-weighted image, but ADC was not as low as lymphoma in our case, and calcification is rare in malignant lymphoma before treatment. In conclusion, the following findings may be characteristic of localized mediastinal amyloidosis: accompanying calcifications on CT, low signal intensity on T2-weighted images, low ADC on DWI, and contrast-enhancement on CT and/or MRI. Conflict of interest All authors have no conflict of interest. References [1] Rodriguez-Romero R, Vargas-Serrano B, Cortina-Moreno B, Fernandez-Gallardo JM, Cervera-Rodilla JL. Calcified amyloidoma of larynx. AJNR 1996;17:1491–3. [2] Urban BA, Fishman EK, Goldman SM, et al. CT evaluation of amyloidosis: spectrum of disease. RadioGraphics 1993;13:1295–308. [3] Ordemann J, Braumann C, Rogalla P, Jacobi CA, Muller JM. Isolated amyloid tumor in the mediastinum: report of a case. Surg Today 2003;33: 202–4. [4] Yong HS, Woo OH, Lee JW, Shu SI, Oh YW, Kang EY. Primary localized amyloidosis manifested as supraclavicular and mediastinal lymphadenopathy. BJR 2007;80:131–3.
[5] Takamori S, Yano H, Hayashi A, et al. Amyloid tumor in the anterior mediastinum: report of a case. Surg Today 2004;34:518–20. [6] Takeshita K, Yamada S, Sato N, et al. An unusual case of mediastinal lymphadenopathy caused by amyloidosis. Intern Med 2000;39:839–42. [7] Hiller N, Fisher D, Shmesh O, Gottschalk-Sabag S, Dollberg M. Primary amyloidosis presenting as an isolated mediastinal mass: diagnosis by fine needle biopsy. Thorax 1995;50:908–9. [8] Georgiades CS, Neyman EG, Barish MA, Fishman EK. Amyloidosis: review and CT manifestations. RadioGraphics 2004;24:405–16. [9] Pickford HA, Swensen SJ, Utz JP. Thoracic cross-sectional imaging of amyloidosis. AJR 1996;168:351–5. [10] Lee J, Krol G, Rosenblum M. Primary amyloidoma of the brain: CT and MR presentation. AJNR 1995;16:712–4. [11] Oruckaptan H, Karli-Oguz K, Isikay I, Ruacan S. Amyloidoma of the temporal bone and upper cervical spine; presentation of a rare clinical entity with a brief literature review. Turk Neurosurg 2009;19:159–62. [12] Gean-Marton AD, Kirsch CFE, Vezina LG, Weber AL. Focal amyloidosis of the head and neck: evaluation with CT and MR imaging. Radiology 1991;181:521–5. [13] Asaumi J, Yanagi Y, Hisatomi M, Konouchi H, Kishi K. CT and MR imaging of localized amyloidosis. EJR 2001;39:83–7. [14] Simoens WA, Van Den Hauwe D L., Van Hedent E, et al. Amyloidoma of the skull. AJNR 2000;21:1559–62. [15] Kato H, Toei H, Furuse M, Suzuki K, Hironaka M, Saito K. Primary localized amyloidosis of the urinary bladder. Eur Radiol 2003;13:109–12. [16] Gandhi D, Wee R, Goyal M. CT and MR imaging of intracerebral amyloidoma: case report and review of the literature. AJNR 2003;24:519–22. [17] Libicher M. Dialysis-related amyloidoma presenting as a bilateral gluteal mass. AJR 2006;186:907–8. [18] Maheshwari AV, Muro-Cacho CA, Kransdorf MJ, Temple HT. Soft-tissue amyloidoma of the extremities: a case report and review of literature. Skeletal Radiol 2009;38:287–92. [19] Quaia E, Tona G, Gelain F, et al. Integrated Fluorine-18 Fluorodeoxyglucose (18 FFDG) PET/CT compared to standard contrast-enhanced CT for characterization and staging of pulmonary tumors eligible for surgical resection. Acta Radiol 2008;49:995–1004. [20] Yadav S, Sharma S, Gilfillan I. Unusual positron emission tomography findings in pulmonary amyloidosis: a case report. J Cardiothoracic Surg 2006;1:32. [21] Currie GP, Rossiter C, Dempsey OJ, et al. Pulmonary amyloid and PET scanning. Respir Med 2005;99:1463–4.
Contents lists available at ScienceDirect
European Journal of Radiology Extra journal homepage: intl.elsevierhealth.com/journals/ejrex
A case of localized amyloidosis in the mediastinum, CT, MRI, and 18 F-FDG-PET/CT findings Mikako Jinnouchi a , Masamitsu Hatakenaka a,∗ , Hidetake Yabuuchi b , Yoshio Matsuo a , Shunya Sunami a , Takeshi Kamitani a , Masahiro Komori a , Yuko Kitajima c , Nobuhiro Fujita d , Hiroshi Honda a a
Department of Clinical Radiology, Graduate School of Medical Sciences, Kyushu University, 3-1-1, Maidashi, Higashi-ku, Fukuoka 812-8582, Japan Department of Health Sciences, Graduate School of Medical Sciences, Kyushu University, Japan Research Institute for Diseases of the Chest, Graduate School of Medical Sciences, Kyushu University, Japan d Department of Anatomic Pathology, Graduate School of Medical Sciences, Kyushu University, Japan b c
a r t i c l e
i n f o
Article history: Received 22 October 2010 Received in revised form 2 December 2010 Accepted 2 December 2010
Keywords: Localized amyloidosis Mediastinum CT MRI FDG-PET
a b s t r a c t Amyloidosis is a heterogeneous group of diseases characterized by the presence of extracellular deposition of amyloid. We present a case of localized amyloidosis of the middle mediastinum, that was diagnosed by trans-esophageal endoscopic ultrasound (EUS)-guided biopsy, focusing on imaging features of contrast-enhanced CT, MRI including dynamic contrast-enhanced study and DWI, and integrated fluorine-18 fluorodeoxyglucose (18 F-FDG) positron emission tomography (PET)/CT. © 2010 Elsevier Ireland Ltd. All rights reserved.
1. Introduction Amyloidosis is a heterogeneous group of diseases characterized by the presence of extracellular deposition of insoluble, fibrillar, proteinaceous material. Amyloidosis is usually seen in a systemic form, and 10–20% of cases can be localized [1–3]. It can be clinically challenging to differentiate mass-forming localized amyloidosis from neoplastic lesions, but there have been several reports regarding imaging findings of localized amyloidosis. To our knowledge, however, there have been few reports regarding its enhancement pattern on dynamic study, and there have been no reports on DWI which would provide somewhat characteristic findings. We present a case of localized amyloidosis of the middle mediastinum, focusing on imaging characteristics. 2. Case A mass lesion of the left hilum was detected on a routine chest radiograph of a 38-year-old originally healthy man. Contrastenhanced CT performed at a neighboring hospital revealed a lobulated mass spreading from the middle mediastinum to the
∗ Corresponding author. Tel.: +81 92 642 5695; fax: +81 92 642 5708. E-mail address: [email protected] (M. Hatakenaka). 1571-4675/$ – see front matter © 2010 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.ejrex.2010.12.003
left hilum without obvious compression of surrounding structures accompanying coarse calcifications and inhomogeneous internal enhancement (Fig. 1). Trans-bronchial lung biopsy did not lead to a definite diagnosis, and he was referred to our hospital for further investigation. MR examination was performed at our hospital with a 1.5T scanner using a sensitivity-encoding cardiac coil. Precontrast axial T1- and T2-weighted spin-echo sequences were obtained at first. DWI was performed by using a multisection spin-echo single-shot echo-planar sequence in the axial plane with b values of 0 and 1000 s/mm2 . Thereafter, apparent diffusion coefficient (ADC) maps were generated. For dynamic contrast-enhancement study, gadopentetate dimeglumine (0.2 ml/kg of body weight) was administered intravenously at a rate of 2 ml/s. MR images were sequentially obtained before and every 30 s for 5 min after contrast material administration. One author (M.J.) manually drew regions of interest (ROIs) for signal intensity measurement. Thereafter, we plotted the average signal intensity within the ROI against time, and a time intensity curve (TIC) was constructed. The mass showed slightly higher signal intensity than that of muscle on T1weighted images and inhomogeneous signal intensity including hypo signal intensity on T2-weighted images (Fig. 2). On DWI with a b value of 1000 s/mm2 , the lesion showed relatively high signal intensity, and the mean ADC was 1.0 (×10−3 mm2 /s) (Fig. 3). TIC showed a rapid increase in signal intensity during the early phase
e40
M. Jinnouchi et al. / European Journal of Radiology Extra 77 (2011) e39–e42
Fig. 1. The contrast-enhanced CT shows an inhomogeneously enhanced mass spreading from the middle mediastinum to the left hilum with coarse calcifications.
Fig. 2. T2-weighted MR image (TR/TE: 1846/100) reveals a mediastinal mass with a heterogeneous low signal intensity.
and washout after the peak. The mass revealed inhomogeneous internal enhancement on delayed images (Fig. 4). 18 F-FDG-PET/CT showed increased uptake of 18 F-FDG corresponding to the mediastinal lesion; the maximal standardized uptake value (SUV) was 4.8 (Fig. 5). For the determination of diagnosis, trans-esophageal EUSguided biopsy was performed. A microscopic view of the specimen (hematoxylin and eosin stain) showed fibrinoid deposition, lymphocyte dominant inflammatory cell infiltration, and eosinophilic acellular material (Fig. 6a). The material was positively stained with Congo-Red stain (Fig. 6b). Immunohistochemically, light
Fig. 4. (a) Axial T1-weighted spin-echo MR image (TR/TE: 923/9.0) obtained 60 s after contrast material administration shows early enhancement. The round cursor marks the ROI selected for signal intensity measurement at dynamic MR imaging. (b) Axial T1-weighted spin-echo MR image (TR/TE: 923/9.0) obtained 300 s after contrast material administration shows a slight washout. (c) TIC shows a rapid peak and washout enhancement pattern.
Fig. 3. DWI (b = 1000 s/mm2 ) shows a mediastinal mass with high signal intensity. The mean ADC was 1.0 (×10−3 mm2 /s).
chains were positive. These histological findings were consistent with AL()-type amyloidosis. Biopsy of the stomach, duodenum, ileum, colon, and rectum did not prove amyloidosis. Bone marrow biopsy revealed normal bone-marrow cells, and he did not have any underlying illness. He was therefore diagnosed as primary localized mediastinal amyloidosis.
M. Jinnouchi et al. / European Journal of Radiology Extra 77 (2011) e39–e42
Fig. 5. The 18 F-FDG-PET shows increased uptake of mediastinal lesion (maximal SUV = 4.8).
18
F-FDG corresponding to the
3. Discussion Amyloidosis is a collection of disease entities that are characterized by the presence of extracellular deposition of insoluble, fibrillar, proteinaceous material with a well-defined -pleated sheet ultrastructure. Clinically, amyloidosis is categorized into two main forms, systemic and localized. Systemic amyloidosis is subclassified into an idiopathic primary form and a secondary or reactive form. Some causes of secondary amyloidosis are plasma cell dyscrasias such as multiple myeloma and chronic inflammatory condition. Amyloidosis is usually seen in a systemic form, and 10–20% of cases can be localized [1,2]. Localized mediastinal amyloidosis is very rare, with only 5 cases having been reported in English literature [3–7], and one of them was a secondary lesion to rheumatoid arthritis [5]. Our case is considered to be the first case of mediastinal amyloidosis in which the diagnosis was made by trans-esophageal EUS-guided biopsy. In four of the six cases (including our case), accompanying calcification was observed on CT [3–5]. Although there have been few reports describing imaging findings [3,4], accompanying calcification is considered to be relatively characteristic [1,3–5,10–12]. This finding is thought to be a result of large amounts of divalent sodium and calcium-bound protein which amyloid fibrils frequently contain [11]. Previously described MR findings of amyloidosis have varied, homo- or inhomogeneous, and hypo to high signal intensity having been observed on both T1- and T2-weighted images [1,2,8–18]. However, hypo signal intensity on T2-weighted images, whether entirely or partially, is considered relatively characteristic [1,10–17]. The exact mechanism of hypo signal intensity on T2-weighted images is uncertain. In some cases it has obviously reflected calcification [1,11], while in other cases it has not. Some hypotheses have been reported. First, protons are fixed in a -pleated sheet and have a long correlation time. Second, pro-
e41
ton density decrease in a -pleated sheet. Third, rapid chemical exchange and spin–spin interactions may occur between the amyloid protein and adjacent water molecules. Fourth, an amyloid microenvironment composed of a heterogeneous micromagnetic mixture of collagen, calcification, and vessels, as well as amyloid fibrils, may cause differences in diamagnetic susceptibility [12]. In addition, various patterns and degrees of enhancement by contrast material have been described on both CT and MRI; no enhancement, homogeneous or inhomogeneous, strong or weak [10,13–17]. However, we found that the majority of amyloidoma showed enhancement of some kind. The mechanism of enhancement is also uncertain. Gean-Marton et al. have reported that remarkable subendothelial deposition of amyloid can be seen histologically within an arteriole, which is indicative of the fragility of vessel [12]. Concerning the dynamic contrast-enhancement study, Asaumi et al. have reported that a case of localized amyloidosis of the tongue exhibited an increase in signal intensity until it reached a plateau, and then a gradual decrease during late and delay phases [13]. They speculated that this pattern might be due to enhancement of the vessels themselves in the mass. It has also been reported that increasing calcification decreased enhancement by contrast material [14]. There has been no literature about DWI findings of amyloidosis. In the present case, relatively low ADC was observed. We speculate that the mechanism for the interruption of diffusion is that a thick, high-viscosity fluid consisting of water, inflammatory cells, and a proteinous matrix causes a marked restriction of water proton mobility. Based on a study investigating the ability of 18 F-FDG PET/CT to distinguish malignant lung tumor from other benign lesions, Quaia et al. have reported a case of amyloidosis diagnosed as malignancy, when they diagnosed a pulmonary nodule/mass as malignancy when SUV > 2.5 [19]. We found another two English reports in which an abnormal uptake of 18 F-FDG to nodular pulmonary amyloidosis was observed, but SUV was not described in the literature [20,21]. In one of these cases, multiple bilateral pulmonary lesions were observed, but only one nodule showed an abnormal uptake of 18 F-FDG, and the rest did not. They reported that whether uptake is observed or not did not depend on nodule size [20]. In these studies, the mechanism of uptake of 18 F-FDG to the lesions of amyloidosis was not discussed. We consider that the chronic inflammatory cell infiltration observed histologically in the present case is somehow related to the uptake mechanism. In some studies, inflammatory cells infiltration has also been histologically observed in the lesions of amyloidosis [3,15]. Amyloidosis might accompany chronic inflammation that could cause abnormal uptake of FDG. In this case, it was difficult to reach a correct diagnosis before biopsy. On CT, the lesion showed a spread from the middle mediastinum to the left hilum and did not show an obvious mass
Fig. 6. (a) Photomicrograph of pathologic specimen of the mediastinal mass obtained in a transesophageal EUS-guided biopsy (Hematoxylin and Eosin stain, high-powerfield) shows fibrinoid deposition, lymphocyte dominant inflammatory cells infiltration, and eosinophilic acellular material. (b) The material was positively stained with Congo-Red stain.
e42
M. Jinnouchi et al. / European Journal of Radiology Extra 77 (2011) e39–e42
effect. This finding made us imagine a relatively soft mass. However, hypointensity on T2WI, strong and rapid enhancement on dynamic contrast-enhancement MR images, and high signal intensity on DWI made us imagine a solid mass with high cellularity and vascularity. We could not find a diagnosis satisfying these findings. Hemangioma could be an appropriate diagnosis for a soft and hypervascular mass with calcification, but low signal intensity on T2-weighted images did not accord with hemangioma. Malignant lymphoma could also be a diagnosis for a soft mass with low signal intensity on T2-weighted image, but ADC was not as low as lymphoma in our case, and calcification is rare in malignant lymphoma before treatment. In conclusion, the following findings may be characteristic of localized mediastinal amyloidosis: accompanying calcifications on CT, low signal intensity on T2-weighted images, low ADC on DWI, and contrast-enhancement on CT and/or MRI. Conflict of interest All authors have no conflict of interest. References [1] Rodriguez-Romero R, Vargas-Serrano B, Cortina-Moreno B, Fernandez-Gallardo JM, Cervera-Rodilla JL. Calcified amyloidoma of larynx. AJNR 1996;17:1491–3. [2] Urban BA, Fishman EK, Goldman SM, et al. CT evaluation of amyloidosis: spectrum of disease. RadioGraphics 1993;13:1295–308. [3] Ordemann J, Braumann C, Rogalla P, Jacobi CA, Muller JM. Isolated amyloid tumor in the mediastinum: report of a case. Surg Today 2003;33: 202–4. [4] Yong HS, Woo OH, Lee JW, Shu SI, Oh YW, Kang EY. Primary localized amyloidosis manifested as supraclavicular and mediastinal lymphadenopathy. BJR 2007;80:131–3.
[5] Takamori S, Yano H, Hayashi A, et al. Amyloid tumor in the anterior mediastinum: report of a case. Surg Today 2004;34:518–20. [6] Takeshita K, Yamada S, Sato N, et al. An unusual case of mediastinal lymphadenopathy caused by amyloidosis. Intern Med 2000;39:839–42. [7] Hiller N, Fisher D, Shmesh O, Gottschalk-Sabag S, Dollberg M. Primary amyloidosis presenting as an isolated mediastinal mass: diagnosis by fine needle biopsy. Thorax 1995;50:908–9. [8] Georgiades CS, Neyman EG, Barish MA, Fishman EK. Amyloidosis: review and CT manifestations. RadioGraphics 2004;24:405–16. [9] Pickford HA, Swensen SJ, Utz JP. Thoracic cross-sectional imaging of amyloidosis. AJR 1996;168:351–5. [10] Lee J, Krol G, Rosenblum M. Primary amyloidoma of the brain: CT and MR presentation. AJNR 1995;16:712–4. [11] Oruckaptan H, Karli-Oguz K, Isikay I, Ruacan S. Amyloidoma of the temporal bone and upper cervical spine; presentation of a rare clinical entity with a brief literature review. Turk Neurosurg 2009;19:159–62. [12] Gean-Marton AD, Kirsch CFE, Vezina LG, Weber AL. Focal amyloidosis of the head and neck: evaluation with CT and MR imaging. Radiology 1991;181:521–5. [13] Asaumi J, Yanagi Y, Hisatomi M, Konouchi H, Kishi K. CT and MR imaging of localized amyloidosis. EJR 2001;39:83–7. [14] Simoens WA, Van Den Hauwe D L., Van Hedent E, et al. Amyloidoma of the skull. AJNR 2000;21:1559–62. [15] Kato H, Toei H, Furuse M, Suzuki K, Hironaka M, Saito K. Primary localized amyloidosis of the urinary bladder. Eur Radiol 2003;13:109–12. [16] Gandhi D, Wee R, Goyal M. CT and MR imaging of intracerebral amyloidoma: case report and review of the literature. AJNR 2003;24:519–22. [17] Libicher M. Dialysis-related amyloidoma presenting as a bilateral gluteal mass. AJR 2006;186:907–8. [18] Maheshwari AV, Muro-Cacho CA, Kransdorf MJ, Temple HT. Soft-tissue amyloidoma of the extremities: a case report and review of literature. Skeletal Radiol 2009;38:287–92. [19] Quaia E, Tona G, Gelain F, et al. Integrated Fluorine-18 Fluorodeoxyglucose (18 FFDG) PET/CT compared to standard contrast-enhanced CT for characterization and staging of pulmonary tumors eligible for surgical resection. Acta Radiol 2008;49:995–1004. [20] Yadav S, Sharma S, Gilfillan I. Unusual positron emission tomography findings in pulmonary amyloidosis: a case report. J Cardiothoracic Surg 2006;1:32. [21] Currie GP, Rossiter C, Dempsey OJ, et al. Pulmonary amyloid and PET scanning. Respir Med 2005;99:1463–4.