Imaging Findings of Head and Neck Inflammatory Pseudotumor

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1 Neuroradiology/Head and Neck Imaging Pictorial Essay Park et al. Head and Neck Neuroradiology/Head and Neck Imaging Pictorial Essay ownloaded from by on 02/16/18 from IP address opyright RRS. For personal use only; all rights reserved Sung in Park 1,2 Jeong Hyun Lee 2 Young heol Weon 3 Park S, Lee JH, Weon Y Keywords: T, head and neck imaging, inflammatory myofibrotic tumor, inflammatory pseudotumor, MRI OI: /JR Received January 15, 2009; accepted after revision March 31, epartment of Radiology, heil General Hospital and Women s Healthcare enter, Kwandong University ollege of Medicine, Seoul, Korea. 2 epartment of Radiology and Research Institute of Radiology, san Medical enter, University of Ulsan, Poongnap-dong, Songpa-gu, Seoul, , Korea. ddress correspondence to J. H. Lee (jeonghlee@amc.seoul.kr). 3 epartment of Radiology, Ulsan University Hospital, University of Ulsan, Ulsan, Korea. ME This article is available for ME credit. See for more information. JR 2009; 193: X/09/ merican Roentgen Ray Society Imaging Findings of Head and Neck OJETIVE. The purpose of this article is to describe imaging features of head and neck inflammatory pseudotumor in the brain, orbit, sinonasal cavity, temporal bone or skull base, and other rare locations. ONLUSION. lthough the radiologic differentiation from malignancy is not clearly possible, we suggest that familiarity with the manifestations of inflammatory pseudotumor can help avoid unnecessary radical surgery before histopathologic proof of malignancy. I nflammatory pseudotumor is a rare benign condition of unknown cause. It is characterized by the presence of a mass that may mimic malignancy and that is composed of spindle cells mixed with variable amounts of extracellular collagen, lymphocytes, and plasma cells [1, 2]. The imaging characteristics and locations of head and neck inflammatory pseudotumor vary widely, with mostly large masses mimicking malignant lesions. lthough imaging features of inflammatory pseudotumor are nonspecific and not characteristic, the role of the radiologist is to ensure that inflammatory pseudotumors are preoperatively suggested diagnoses and are differentiated from malignant lesions either by particular imaging findings or by imagingguided biopsy. In this article, we describe the imaging features of head and neck inflammatory pseudotumor in the brain, orbit, sinonasal cavity, temporal bone or skull base, and other rare head and neck locations. Pathogenesis and linical Manifestations of the Inflammatory Pseudotumor Inflammatory pseudotumor is a chronic inflammatory tumefaction of unknown origin. The cause and pathogenesis of inflammatory pseudotumor remains controversial. Recently, the term inflammatory myofibroblastic tumor has emerged from the broad category of inflammatory pseudotumor and has come to be commonly used on the basis of electron microscopic and immunohis- tochemical findings [3, 4]. Recent studies have revealed cytogenetic clonal abnormality and anaplastic lymphoma kinase expression, suggesting a neoplastic cause [5, 6]. However, inflammatory pseudotumor of the lymph node and spleen is a nonneoplastic entity distinct from inflammatory myofibroblastic tumor. Furthermore, the family of idiopathic fibrosclerosing lesions, including sclerosing mesenteritis, idiopathic retroperitoneal fibrosis, sclerosing mediastinitis, and orbital inflammatory pseudotumor, may also be considered within the umbrella of inflammatory pseudotumor [7]. Thus inflammatory myoblastic tumor is not the same as inflammatory pseudotumor. Inflammatory pseudotumor most commonly involves the lung and orbit, but it has been described in almost any location, in both sexes, at all ages [1 3]. Most cases occur in childhood or early adulthood and may be asymptomatic or associated with constitutional complaints or symptoms, including unexplained fever and weight loss, and may be related to local mass effects [2, 4]. Inflammatory pseudotumors clinically masquerade as malignant growths, and their clinical significance thus lies in the difficulty encountered in preoperatively excluding malignancy. The preoperative recognition of this benign lesion is important to avoid unnecessary radical resection. lthough several cases of spontaneous regression and response to the medical treatment have been reported, in consideration of its pathologic features and clinical manifestations, complete surgical resection is mandatory, with the exception 1180 JR:193, October 2009

2 Head and Neck ownloaded from by on 02/16/18 from IP address opyright RRS. For personal use only; all rights reserved of steroid therapy for orbital inflammatory pseudotumor. The prognosis of inflammatory pseudotumor is generally considered to be favorable if complete surgical resection is done, with only a rare incidence of malignant transformation and remote metastasis [2]. Radiologic Features of the lthough the radiologic findings of inflammatory pseudotumor are nonspecific, particular findings are observed. Ultrasound shows a variable pattern of echogenicity with ill-defined or well-defined margins. Prominent vascularity may be shown with color or power oppler ultrasound, especially contrast-enhanced power oppler ultrasound. Enhanced T may show homo- or heterogeneity and hypo-, iso-, or hyperdensity [8]. MRI shows a hypointense lesion on T1- and T2-weighted images (possibly explained by the relative lack of mobile protons within fibrotic lesions) and shows marked gadolinium enhancement. elayed enhancement has frequently been observed, probably because of the accumulation of extravascular contrast media in fibrotic lesions [9]. of the rain Inflammatory pseudotumor is extremely rare in the NS without the involvement of other organ systems. These diseases may be located in the brain parenchyma (Fig. 1), attached to the dura (Fig. 2), or, rarely, may involve both [10]. Lack of neovascularization was shown by reduced cerebral blood volume on perfusion MRI (Fig. 1) and detection of lactate on MR spectroscopy, suggesting hypoxia and inflammatory reaction. Loss of normal neural elements caused by proliferation of inflammatory cells can be visualized by reduction of N-acetylaspartate on MR spectroscopy and loss of fractional anisotropy on diffusion tensor MRI. Increase of cellularity and cell membrane synthesis due to inflammatory cells hyperplasia has been visualized by an increase of choline in MR spectroscopy [10]. of the Orbit Orbital pseudotumors are the third most common primary tumor of the orbit. The incidence has been reported to be 9% of all orbital mass lesions and these tumors are a common cause of unilateral proptosis in adults [1, 11]. Orbital pseudotumor is diagnosed by exclusion, on the basis of the patient s history, clinical course, response to steroid therapy, laboratory tests and, biopsy findings. The symptoms of orbital pseudotumors reflect the degree of the inflammatory response (acute, subacute, or chronic) and the location of the inflammatory tissue [11, 12]. They usually show an abnormal intraorbital soft-tissue mass density that varies considerably in size, shape, and location. On T, a moderately enhancing mass is usually seen (Fig. 3). Orbital pseudotumors are commonly accompanied by fat infiltration or edema. bony change reflected by hyperostosis and remodeling favors the diagnosis of a longstanding benign process, such as an orbital pseudotumor that is sometimes found to extend through the superior orbital fissure and to enlarge and erode the fissure compared with the normal side. MRI shows a hypointense lesion on T1- and T2-weighted images and shows marked gadolinium enhancement. Fat-suppression techniques clearly show an optic nerve sheath lesion and intraorbital inflammation. The spectrum of orbital involvement varies from localized periscleritis or perineuritis to diffuse orbital inflammation frequently involving the lacrimal gland and the muscular cone. When the muscular cone is involved, imaging studies, including T and MRI, characteristically reveal thickening of the extraocular muscle belly and relative sparing of the tendon [11, 13]. However, extension beyond the orbit can occur in cases of extensive and chronic orbital inflammation [11] (Fig. 4). The middle cranial fossa and cavernous sinus are the two most common locations into which extensions are observed. irect intracranial spread can occur through the superior orbital fissure, the inferior orbital fissure, or the optic canal [12]. of the Sinonasal avity Sinonasal inflammatory pseudotumors have a more aggressive appearance than those of the orbit, with bony changes such as erosion, remodeling, and sclerosis being common [14] (Figs. 5 and 6). haracteristics include less response to corticosteroid treatment than orbital pseudotumors; if the tumor is completely resected, the prognosis is good. of the Temporal one or Skull ase Inflammatory pseudotumors rarely occur in the temporal bone or skull base. It is very difficult, both clinically and radiologically, to determine whether an infiltrating soft-tissue mass located in the temporal bone or skull base, with bone destruction, is an inflammatory pseudotumor or a malignant neoplasm [15, 16]. ommon MRI findings in all reported cases are low signal intensity on T2-weighted images and homogeneous contrast enhancement (Figs. 7 and 8). ural thickening and enhancement are nonspecific reactive changes to any adjacent dural lesion and can also manifest with malignant neoplasm (Figs. 7 and 8). The pattern of a soft-tissue mass characterized by low signal intensity on T2- weighted images, marked contrast enhancement, a peculiar destruction of the mastoid, and sparing of the inner ear and of the ossicular chain is contraindicative of an aggressive tumor and likely suggests a chronic inflammatory lesion [15]. Other Rare Locations of Head and Neck Other rare locations include inflammatory pseudotumor in the soft tissue of the neck (Fig. 9), the infratemporal fossa, the nasopharynx including the parapharyngeal space, the pterygopalatine fossa, the larynx, and the major salivary gland. onclusion The imaging characteristics and locations of head and neck inflammatory pseudotumor vary widely, from the more frequent benign lesions such as large masses mimicking malignant lesions to the rare tumors that are multifocal and prone to recurrence and malignant transformation (Fig. 6). Inflammatory pseudotumor can also manifest as brain abscess (Fig. 1) and meningioma (Fig. 2). The role of the radiologist is to ensure that inflammatory pseudotumors are preoperatively suggested diagnoses and differentiated from malignant lesions either by particular imaging findings or by imaging-guided biopsy. Thus, although the radiologic differentiation from malignancy is not clearly possible, we suggest that familiarity with the manifestations of inflammatory pseudotumor can help avoid unnecessary radical surgery before histopathologic proof of malignancy. References 1. Narla L, Newman, Spottswood SS, Narla S, Kolli R. Inflammatory pseudotumor. Radio- Graphics 2003; 23: Park S, ho KS, Kim JK, et al. Inflammatory pseudotumor (myoblastic tumor) of the genitourinary tract. JR 2008; 191: offin M, Watterson J, Priest JR, ehner LP. JR:193, October

3 Park et al. Extrapulmonary inflammatory myofibroblastic blastic tumours: where are we now? J lin Pathol orbital inflammatory pseudotumors with extraor- tumor (inflammatory pseudotumor): a clinico- 2008; 61: bital extension. Korean J Radiol 2005; 6:82 88 pathologic and immunohistochemical study of behsera M, Vilgrain V, elghiti J, Flejou JF, Na- 13. Frohman LP, Kupersmith MJ, Lang J, et al. In- cases. m J Surg Pathol 1995; 19: hum H. Inflammatory pseudotumor of the liver: tracranial extension and bone destruction in or- 4. offin M, ehner LP, Meis-Kindblom JM. In- radiologic pathologic correlation. J omput s- bital pseudotumor. rch Ophthalmol 1986; 104: flammatory myofibroblastic tumor, inflammatory sist Tomogr 1995; 19: ownloaded from by on 02/16/18 from IP address opyright RRS. For personal use only; all rights reserved fibrosarcoma, and related lesions: an historical review with differential diagnostic considerations. Semin iagn Pathol 1998; 15: iselli R, Ferlini, Fattorossi, oldrini R, osman. Inflammatory myofibroblastic tumor (inflammatory pseudotumor): N flow cytometric analysis of nine pediatric cases. ancer 1996; 77: Lawrence, Perez-tayde, Hibbard MK, et al. TPM3-LK and TPM4-LK oncogenes in inflammatory myofibroblastic tumors. m J Pathol 2000; 157: Gleason, Hornick JL. Inflammatory myofibro- 9. Nam KJ, Kang HK, Lim JH. Inflammatory pseudotumor of the liver: T and sonographic findings. JR 1996; 167: Weber M, Viehoever, Stieltjes, et al. Intracerebral manifestation of an atypical monoclonal plasma cell hyperplasia depicted by MR perfusion and diffusion tensor imaging and MR spectroscopy. JR 2005; 185: Weber L, Romo LV, Sabates NR. Pseudotumor of the orbit: clinical, pathologic, and radiologic evaluation. Radiol lin North m 1999; 37: , xi 12. Lee EJ, Jung SL, Kim S, et al. MR imaging of 14. e Vuysere S, Hermans R, Sciot R, revits I, Marchal G. Extraorbital inflammatory pseudotumor of the head and neck: T and MR findings in three patients. m J Neuroradiol 1999; 20: Gasparotti R, Zanetti, olzoni, Gamba P, Morassi ML, Ungari M. Inflammatory myofibroblastic tumor of the temporal bone. m J Neuroradiol 2003; 24: Han MH, hi JG, Kim MS, et al. Fibrosing inflammatory pseudotumors involving the skull base: MR and T manifestations with histopathologic comparison. m J Neuroradiol 1996; 17: E Fig year-old man with inflammatory pseudotumor of brain. Inflammatory pseudotumor manifests parenchymal involvement and mimics abscess. and, T2-weighted () and FLIR () MR images show high-signal-intensity lesion with peripheral dark signal intensity rim in right parietal area. Perilesional high signal intensity, presumed edema, is also evident., ontrast-enhanced T1-weighted MR image shows peripheral rim enhancement., iffusion-weighted MR image shows high-signal-intensity lesion in right parietal area. High signal intensity due to perilesional edema on T2-weighted MR image changes to dark signal intensity. E, Perfusion-weighted MR image shows blue lesion in right parietal area, suggestive of decreased perfusion compared with surrounding red colored coding normal brain parenchyma JR:193, October 2009

4 Head and Neck ownloaded from by on 02/16/18 from IP address opyright RRS. For personal use only; all rights reserved Fig year-old man with inflammatory pseudotumor of brain. Inflammatory pseudotumor is attached to dura and manifests as meningioma., T1-weighted MR image shows dural-based iso- to slightly low-signal-intensity lesion in left parietal area., T2-weighted MR image shows dark signal intensity lesion that was falsely identified as calcified mass. and, ontrast-enhanced T1-weighted MR images show strong homogeneous enhancement of mass and surrounding dura (arrow, ). Radiologic diagnosis was calcified meningioma. Surgically excised specimen indicated lymphoplasma cell rich inflammatory pseudotumor. Fig year-old woman with inflammatory pseudotumor of orbit who presented with left-sided diplopia and proptosis. and, xial T scans of orbit show homogeneously enhancing soft-tissue mass (M) in left lacrimal gland. Mass is attached to left lateral and superior rectus muscle. ony changes such as erosion and sclerotic change (arrow) are also evident. Patient was treated with high dose of corticosteroids, and symptoms resolved. JR:193, October

5 Park et al. ownloaded from by on 02/16/18 from IP address opyright RRS. For personal use only; all rights reserved Fig year-old woman with orbital inflammatory pseudotumor and extraorbital extension., xial T scan of orbit shows suspicious soft-tissue density in right cavernous sinus (arrow)., T1- and T2- weighted axial MR images showed iso- and low-signal-intensity lesion (not shown). ontrast-enhanced T1-weighted MR image shows plaquelike enhancing lesion (arrow) in right temporal pole to cavernous sinus. Tolosa-Hunt syndrome is suggested. Fig year-old woman with inflammatory pseudotumor of nasal cavity. and, xial () and coronal () T scans show soft-tissue lesion in nasal cavity. Mild nasal septal deviation to left side is also evident., Photomicrograph of histologic specimen shows loosely arranged spindle cells, admixed collagen bundles, and scattered inflammatory infiltrate. Mitotic activity was low, and cellular atypia was minimal. (H and E, original magnification 40), On higher power, photomicrograph of histologic specimen shows cytologically bland spindle cells with prominent admixture of lymphocytes and plasma cells. (H and E, original magnification 400) E, Photomicrograph of immunohistochemistry shows strong positive finding of myofibroblasts for smooth muscle actin. (Original magnification 400) E 1184 JR:193, October 2009

6 Head and Neck ownloaded from by on 02/16/18 from IP address opyright RRS. For personal use only; all rights reserved Fig year-old man with inflammatory pseudotumor and malignant transformation of left maxillary sinus. Patient had left gingival pain for 6 months. and, xial () and coronal () T scans show soft-tissue lesion (M in ) in left maxillary sinus. ssociated massive bony destructions are evident. Radiologic primary diagnosis was malignant lesion with bony destruction. Wide excision was performed. Pathologic results indicated inflammatory pseudotumor with malignant transformation. Fig year-old woman with inflammatory pseudotumor of temporal bone. and, T1- () and T2- () weighted MR images show intermediate signal intensity lesion in right mastoid and petrous portion of right temporal bone. and, ontrast-enhanced T1-weighted MR images show strong homogeneous enhancement of mass and surrounding dura (arrows, ). Extension to cavernous sinus is also evident. JR:193, October

7 Park et al. ownloaded from by on 02/16/18 from IP address opyright RRS. For personal use only; all rights reserved Fig year-old woman with inflammatory pseudotumor of skull base. and, T1- () and T2- () weighted MR images show iso- and slightly high-signal-intensity lesion in right middle cranial fossa and skull base. and, ontrast-enhanced T1-weighted MR images show strong homogeneous enhancement of bony destructive mass and surrounding dura. Extension to cavernous sinus engulfing right carotid artery (arrow, ), ethmoid sinus, temporal bone, and clivus is also evident. Fig year-old girl with inflammatory pseudotumor of soft tissue of neck. and, xial () and coronal () T scans of neck show ill-defined homogeneously enhancing softtissue mass (M) in left posterior cervical area and extension to carotid space and subcutaneous layer. ssociated lymphadenopathies (arrows, ) are also evident. FOR YOUR INFORMTION This article is available for ME credit. See for more information JR:193, October 2009