Xanthogranuloma of Sellar Region: A Case Report with Diagnostic Imaging Findings, Treatment Response and Literature Review

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1 J Radiol Sci 2012; 37: Xanthogranuloma of Sellar Region: A Case Report with Diagnostic Imaging Findings, Treatment Response and Literature Review Shang-Ta Tsai Yu-Kun Tsui Miriam Wan-Ling Wu Tai-Yuan Chen Wen-Sheng Tzeng Department of Medical Imaging, Chi Mei Medical Center, Yong-Kang, Tainan, Taiwan Abstract Xanthogranuloma of sellar region is uncommon and difficult to differentiate from craniopharyngioma, Rathke s deft cyst and other sellar lesions by imaging findings. In this article, we report a rare case of sellar xanthogranuloma in a 49-year-old woman who presented with headache and visual defect. Computed tomography (CT), magnetic resonance imaging (MRI), and partial surgical excision were performed and pathology confirmed the diagnosis. Postoperative follow-up series of imaging studies demonstrated the residual tumor evolution in various size and partial response to the radiotherapy. Current evidence regarding to the clinicopathologic and radiological features of sellar xanthogranuloma will be summarized, along with discussion on its main differential diagnoses. The World Health Organization (WHO) accepted xanthogranuloma of sellar region as a specific brain tumor classification in 2000, separating it from the classical adamantinomatous craniopharyngioma. Histopathologically, xanthogranuloma of sellar region is characterized by the presence of cholesterol cleft, macrophages, chronic inflammatory infiltrates and hemosiderin deposition [1]. It typically causes symptoms of endocrinological deficits and visual change with favorable outcome. The first series of 37 cases were described by Paulus et al. in 1999 [1], and only twelve case reports of sellar xanthogranuloma have subsequently been documented since 2000[3-14]. Xanthogranuloma of the sellar region is rare. Herein, we present the first case in current literature which describes the long-term follow-up images of the residual tumor and response to radiotherapy. Case presentation A 49 year-old woman suffered from headache with progressively blurred vision for one year. Ophthalmologic evaluation revealed total visual field (VF) defect in Oculus Dexter (OD) and temporal VF defect in Oculus Sinister (OS). Endocrinological tests showed hypopituitarism with secondary adrenal insufficiency and hypothyroidism, which was treated with short course of hydrocortisone. CT scan revealed a large cystic mass at the sellar and suprasellar region with some scattered peripheral calcification (Fig. 1a). MRI showed a lobulated sellar-suprasellar mass with homogeneous hyperintensity on both T1-weighted and T2-weighted images, peripheral rim-like hypointensity, and optic chiasma compression. Some hypointense deposits at the depending portion of the lesion caused a fluid-fluid level (Fig. 1b, 1c) appearance. The mass showed no enhancement after gadolinium administration (Fig. 1d) and no diffusion restriction on diffusion-weighted images (DWI) (Fig. 1e). The patient was then admitted to our hospital and underwent right orbital-zygomatic craniotomy for partial removal of the tumor under a presumptive diagnosis of craniopharyngioma. During operation, a 4 x 4 x 5 cm soft encapsulated gray tumor was found over the sellar region Correspondence Author to: Yu-Kun Tsai Department of Medical Imaging, Chi Mei Medical Center, Yong-Kang, Tainan, Taiwan No.901, Zhong-Hua Road, Yong-Kang, Tainan 710, Taiwan J Radiol Sci June 2012 Vol.37 No.2 89

2 with suprasellar extension and tight compression of the right optic nerve and optic chiasm. The tumor was cystic with cholesterol and bile-like fluid. Microscopic study of the surgical specimen showed that the tumor was composed of macrophages, giant cells with lymphocytic infiltration, dystrophic calcification, cholesterol cleft formation and hemosiderin deposition (Fig. 2). There were tiny sloughed squamous epithelia identified. The histological diagnosis of sellar xanthogranuloma was rendered. The postoperative course was uneventful except for the presence of transient diabetes insipidus. Postoperatively there were minimal recovery of the visual acuity (OD from blindness to 0.1) and mild improvement of bitemporal hemianopia. However, the hypopituitarism was still noted. Post-operative MRI was arranged 6 months later and demonstrated a residual sellar tumor measuring about cm. The sequential annual MRI for the next three years showed tumor evolution with various diameters from 2.8 to 3.5cm. The follow-up MRI about 20 months after surgery revealed the prominent dark signal intensity with "blooming" effect on the gradient echo sequence and susceptibility-weighted images (SWI) (Fig. 3a, 3b). He was then referred for post-operative radiotherapy which consisted of a total radiation dose of 2500 cgy in 5 fractions. The tumor showed marked shrinkage of the size (2.2 cm) about one year later. Figure 1 1a 1b 1c 1d 1e Figure 1. A 49-year-old woman with xanthogranuloma of sellar region. Noncontrast-enhanced CT scan a. shows a large cystic mass at sellar and suprasellar region with scattered calcifications. Axial MRI T1-weighted image b. and T2-weighted image c. of brain show a lobulated hyperintense mass with hypointense cystic wall (white arrows) and fluid-debris level (black arrows). The cystic mass (asterisk) shows no enhancement after gadolinium administration d. and no diffusion restriction on DWI (b=1000 Fig. 1e). 90 J Radiol Sci June 2012 Vol.37 No.2

3 Discussion Xanthogranulmatous reaction (Cholesterol granuloma) is characterized by cholesterol clefts, macrophages (xanthoma cells), hemosiderin deposits, chronic inflammatory infiltrates, and fibrous proliferation. It may occur at various sites both inside and outside the cranial vault due to obstruction of a cavity, chronic inflammation, hemorrhage and foreign-body reaction [1]. Most xanthogranulomatous reactions at the sellar region are associated with epithelial lesions including craniopharyngioma, Rathke's cleft cyst, colloid cyst, and rarely pituitary adenoma [2]. In 1999, Paulus et al. reported in a series of cases where xanthogranulomatous reaction lacked epithelial component at the sellar region. These lesions appeared clinicopathologically distinct from the classical adamantinomatous craniopharyngiomas because they caused marked endocrine deficits and intrasellar involvement, in contrast with craniopharyngioma [1]. Furthermore, they had more favorable postoperative outcomes [1]. The entity was, therefore, later named "xanthogranuloma of the sellar region" and added to the WHO brain tumor classification in Recent reports suggest that an accurate preoperative diagnosis of xanthogranuloma of the sella, either clinical or radiological, is very difficult. There are no typical radiological characteristics for xanthogranuloma [3]. MRI was performed in all 19 reviewed cases [3-14] (Table 1, with addition of the present case). Almost all lesions appeared high signal intensity on T1-weighted images without or with subtle enhancement, and most cases also revealed high Figure 2 Figure 2. Histopathology (H&E stain, 100X). Microscopically, the tumor is composed of macrophages, giant cells with lymphocytic infiltration, dystrophic calcification, cholesterol cleft formation (arrows) and hemosiderin deposition. Figure 3 Figure 3. Post-operative MRI with gradient echo sequence a. and SWI minip image b. reveal the tumor (white arrows) with prominent dark signal intensity and blooming effect. 3a 3b J Radiol Sci June 2012 Vol.37 No.2 91

4 Table 1. Reviewed MRI features of xanthgranuloma of the sellar region Reviewed MRI features of xanthgranuloma of the sellar region Author(year) Age/ Sex MRI appearance T1WI T2WI Gd-enhancement FDL PHR Reithmeier et al. (2002) 51/M high NA heterogeneous Yonezawa et al. (2003) 67/M high heterogeneous No Burl et al. (2003) 29/M heterogeneous heterogeneous periphery, eterogeneous 26/M high high No + Murao et al. (2005) 47/M high high periphery Jung et al. (2006) 57/F mainly high mainly high heterogeneous + 5/M heterogenous heterogeneous NA Tajima et al. (2006) 9/M high high No + 6/M high low No + Liu et al. (2008) 32/M high high No + + Moriya et al.(2008) 54/M high mainly high No Sugata et al. (2009) 26/M Iso low heterogeneous Arai et al. (2010) 55/F high mainly high No + + Šulentić et al. (2010) 40/M NA NA NA Kamoshima et al. (2011) 8/F high low No + 11/M high iso No + 12/F heterogeneous heterogeneous heterogeneous + 10/F high heterogeneous No + 5/M high low No Present Case 49/F high mainly high No + + F, female; M, male; NA, not available; T1WI, T1-weighted image; T2WI, T2-weighted image FDL, fluid-debris level; PHR, peripheral hypointense rim signal intensity on T2-weighted images. The cholesterol or cholesterol clefts of a xanthogranuloma demonstrated T1 high-signal intensities. The cysts containing xanthochromic-like fluid showed T1 high/iso- and T2 high-signal intensities. In addition to xanthogranuloma, an expansive mass with T1 signal hyperintensity in the sellar and juxtasellar regions due to clotting of blood, fat, high-protein materials, or other paramagnetic substance [15] generates a list of differential diagnosis, of which craniopharyngioma, Rathke s deft cyst, pituitary apoplexy/hemorrhagic pituitary adenoma, and aneurysm are of prime importance. Craniopharyngiomas typically appear as heterogeneously enhancing lesions with a tripartite structure of solid, calcified, and cystic components which may contain a high concentration of protein. Rathke s deft cysts appear as nonenhancing intrasellar rounded lesions locating at the midline between the anterior and posterior pituitary lobes. The cysts typically have a homogeneously hyperintense T1 signal and, often, a hypointense T2 signal, but show neither signs of calcification nor contrast enhancement. Pituitary apoplexy or hemorrhagic pituitary adenoma presents with heterogeneous signal intensity, with predominant hyperintensity on T1- weighted images and predominant hypointensity on T2-weighted images resulting from the methemoglobin of clotting blood in early course. At a later stage, the sedimentation of blood products may create a fluid-debris level within the mass [15]. Classic feature of intracranial aneurysm with rapid internal blood flow presents as internal signal void on spin-echo MR images [15]. However, in thrombosed aneurysms, the inner-luminal signal intensity is dependent on the age and distribution of the coagulated blood and the presence of calcifications [3]. 92 J Radiol Sci June 2012 Vol.37 No.2

5 Dermoid cysts are extraaxial congenital ectodermal inclusion cysts which occur frequently in the sellar or parasellar region [17]. The fat contents of dermoid cysts contribute to pathognomonic MR appearance of T1-hyperintensity with signal loss by fat suppression techniques. Epidermoid cysts are congenital inclusion cysts and composition with cholesterol in a solid crystalline state and keratin within the tumor. Epidermoid cyst occasionally occur in the sellar/ parasellar regions (10%-15%) [17]. They typically are nonenhanced isointense or slightly hyperintense to CSF on both T1- and T2-weighted MR images with characteristic hyperintense signal on diffusion-weighted MR imaging (DWI). Rare white epidermoids have high protein content and may appear high signal intensity on T1-weighted images [17]. Clearly, distinguishing xantogranloma from the long list of differential diagnosis at the sellar region will be difficult radiologically. MRI features are often complex, reflecting the heterogeneous histologies, especially in those sellar lesions accompanied with xanthogranulomatous reaction as mentioned above. Despite this, some radiological characteristics may offer a clue to distinguish xanthogranuloma from other differential diagnoses. Firstly, the MR appearance of cholesterol granulomas presents a thin peripheral rim of low signal intensity suggestive of cortical bone protuberance and/or the presence of hemosiderin [15]. It is different from pituitary apoplexy which may demonstrate thickening of the mucosa of the adjacent sphenoid sinus [15]. Secondly, the fluid-fluid level (or fluid-debris level) caused by the interface between the high signal xanthogranulomatous component and the necrotic debris has been observed in previous study, described as focal hypointensity at the tumor base [10] or lower signal intensity in the inferior portion [6]. Such MR feature is observed mainly in chronic hemorrhagic pituitary adenoma but rarely in Rathke s cleft cyst or craniopharyngiomas [15]. Thirdly, xanthogranuloma with prominent and diffuse hemosiderin deposition may result in obvious dark signal with blooming effect on gradient echo sequence and SWI. Even though postoperative hematoma or other hemorrhagic lesions such as pituitary apoplexy or hemorrhagic dermoid/epidermoid cysts may demonstrate likewise feature, they rarely present simultaneously high signal intensity on both T1 and T2-weight images in the chronic stage of hemorrhage. The heterogeneous hyperdense appearance of resorbed hematoma on non-contrast-enhanced CT and correlation with onset symptoms may also be helpful. All reported cases of xanthogranuloma of the sella had favorable overall outcome without relapses after complete resection, except one case associated with sarcoidosis [13] that revealed possible residue or relapse. Our case is another case of residual xanthogranuloma due to incomplete resection. Surgical removal is necessary to obtain the correct diagnosis and reduce the mass effect [12]. Both transphenoidal and transcranial approaches may be used to access the mass [10]. We demonstrate that combination of radiotherapy may be an alternative treatment to reduce the mass effect in the residual tumor. Radiotherapy has been reported for treatment of orbital xanthogranuloma (Erdheim-Chester disease), juvenile xanthogranuloma and necrobiotic xanthogranuloma [16]. Since reports on xanthogranuloma of sellar region are rare, further studies are required to understand the exact mechanism and response of radiotherapy. In conclusion, we describe the pre- and postoperative radiological characteristics of a case of sellar xanthogranuloma and its response to radiotherapy. The clinicopathologic aspects of sellar xanthogranuloma and differential diagnoses are also discussed, in the hope to understand the true nature and clinical course of this rare disease. Reference 1. Paulus W, Honegger J, Keyvani K, Fahlbusch R. Xanthogranuloma of the sellar region: a clinicopathological entity different from adamantinomatous craniopharyngioma. Acta Neuropathol (Berl) Olami U 1999; 97: Nishioka H, Shibuya M, Ohtsuka K, Ikeda Y, Haraoka J. Endocrinological and MRI features of pituitary adenomas with marked xanthogranulomatous reaction. Neuroradiology 2010; 52: Jung CS, Schanzer A, Hattingen E, et al. Xanthogranuloma of the sellar region. Acta Neurochir 2006; 148: Reithmeier T, Trost HA, Wolf S, et al. Xanthogranuloma of the Erdheim-Chester type within the sellar region: Case report. Clin Neuropathol 2002; 21: Yonezawa K, Shirataki K, Sakagami Y, et al. Panhypopituitarism induced by cholesterol granuloma in the sellar region: Case report. Neurol Med Chir (Tokyo) 2003; 43: Burt MG, Morey AL, Turner JJ, et al. Xanthomatous pituitary lesions: A report of two cases and review of the literature. Pituitary 2003; 6: Murao K, Imachi H, Ishida T, et al. Panhypopituitarism induced by xanthogranuloma of the sellar region. Nippon Naika Gakkai Zasshi 2005; 94: Taijima T, Sawamura Y, Ishizu K, et al. Two children with xanthogranuloma of the sellar region. Clin Pediatr Endocrinol 2006; 15: Moriya S, Nimura T, Utsunomiya A, et al. Xanthogranuloma of the sellar region: a case report and review of literatures. No Shinkei Geka Sokuho 2008; 18: Liu ZH, Tzaan WC, Wu YY, et al. Sellar xanthogranuloma manifesting as obstructive hydrocephalus. Journal of Clinical Neuroscience 2008; 15: J Radiol Sci June 2012 Vol.37 No.2 93

6 11. Sugata S, Hirano H, Yatsushiro K, et al. Xanthogranuloma in the suprasellar region. Neurol Med Chir (Tokyo) 2009; 49: Arai A, Nishinara M, Sasayama T, et al. Xanthogranuloma of the sellar region. Neurol Med Chir (Tokyo) 2010; 50: Šulentić P, Čupić H, Čerina V, et al. Xanthogranuloma of the sellar region in a patient with sarcoidosis. Acta Clin Croat 2010; 49: Kamoshima Y, Sawamura Y, Motegi H, et al. Xanthogranuloma of the sellar region of children: series of five cases and literature review. Neurol Med Chir (Tokyo) 2011; 51: Bonneville F, Cattin F, Marsot-Dupuch F, et al. T1 Signal Hyperintensity in the Sellar Region: Spectrum of Findings. RadioGraphics 2006; 26: Aristizabal SA, Runyon TD. Radiotherapy of unusual benign disease. Int J Radiat Oncol Biol Phys 1981; 7: Osborn AG, Preece MT. Intracranial cysts: radiologicpathologic correlation and imaging approach. Radiology. 2006; 239: J Radiol Sci June 2012 Vol.37 No.2