Acta Chir Belg, 2013, 113, 298-300
Presacral Ganglioneuroma with Abnormal FDG Uptake : a Case Report S. Holz, C. Keyzer, J. Van Stadt, S. Willemart, E. Chasse Dept. of Surgery, Belgium
Abstract. Ganglioneuromas are rare, benign, well-differentiated, slowgrowing tumors of the sympathetic nervous system, composed of large, mature neurons in a stroma composed of Schwann cells. Ganglioneuromas are derived from the neural crest cells and can arise anywhere from the base of the skull to the pelvis. The pre-sacral area is a very rare location for ganglioneuromas to develop. We describe the case of a 31 year old woman, who was incidentally found to have an abnormal pre-sacral mass. The following work-up, revealed the mass to be growing on imagery (computed tomography and magnetic resonance imagery) and fluorine-18 fluorodeoxiglucose avid. The mass was removed by assisted laparoscopy and was found to be a benign ganglioneuroma . This is the first described case of fluorine-18 fluorodeoxiglucose avid, pre-sacral, benign ganglioneuroma.
Introduction Ganglioneuromas (GN) are rare, benign, well-differentiated, slowgrowing tumors of the sympathetic nervous system , composed of large, mature neurons in a stroma composed of Schwann cells. GN are derived from the neural crest cells and can arise anywhere from the base of the skull to the pelvis (1). The two most common sites for GN are the retroperitoneum and posterior mediastinum, followed by the cervical region (2). The presacral space is a very rare location, so far only 21 cases have been described in literature (3, 4, 5, 6, 7, 8). Case report A 31 year old women presented for routine preconceptional examination . Her medical, surgical and gynecological report was without particularities. She had no neurological or other complaints. An abnormal presacral mass was found on endo-vaginal ultra-sound. To determine the origin of the incidental finding, further diagnostic work-up was necessary. It consisted of Magnetic Resonance Imaging (MRI), Computed Tomography (CT), colonoscopy and endo-anal ultrasound for biopsies. A globally ovale (31 × 50 × 49 mm), well delimited(independent from any surrounding, urologic, gynecologic, digestive or vascular structures), solid left mesorectal mass, anterior to the pre-sacral fascia was found. containing no fat nor calcifications anterior to the pre-sacral fascia was found. The mass was heterogeneous on MRI and contained no fat (hypo-intense on T1 ponderation, hyper-intense on T2 ponderation, with progressive enhancement of its inner portion after the injection of gadolinium) and contained no calcifications on CT. This features evoked the diagnosis of Schwannoma. The other abnormality found on imagery,
Fig. 1 Axial T2 Weighted MR image showing a pre-sacral solid well defined mass with a heterogeneous moderate high-signal intensity (arrows). Note also the presence of bilateral ovarian cysts (arrowheads).
was the presence of benign bilateral ovarian cysts. Unfortunately the repeated (twice) ultrasound guided biopsies did not permit a clear and precise histological diagnosis. The colonoscopy was without particularities. After a multidisciplinary discussion the decision was taken to complete the work-up with a fluorine-18 fluorodeoxiglucose positron emission tomography combined with CT(18F-FDG PET-CT) and to follow the evolution with a new MRI 4 months later. This latter revealed a slight growth of the mass, from 49 × 34 × 45 mm to 53 × 37 × 47 mm (Fig. 1). The PETCT revealed a moderate FDG uptake in the mass, with a maximal Standard Uptake Value (SUVmax) of 3.18, evaluated 90 minutes after the injection of 363 MBq (Mega Becquerel) (Fig. 2). Due to the tumoral growth an abnormal FDG-uptake the decision was taken to surgically remove the pelvic
Presacral Ganglioneuroma with Abnormal FDG Uptake
Fig. 2 Sagittal fused PET/CT image showing the 18F-FDG–avid presacral mass (arrow).
incidentaloma. A laparoscopic dissection of the mesorectal plane was performed and found the mass to be totally independent from any digestif, urologic or gynecologic structures, but strongly adherent to the posterior sacral plan. Due to the high risk of massive hemorrhage inherrent to anatomically close important vascular structures and potential hypervascularisation of the mass (4), the decision was taken to hand-assist the end of the laparoscopic precedure by a small supra-pubic Pfannenstiel incision. The mass was safely removed with complete macroscopic excision. The post-operative course was uneventful and the patient was discharged on the second post-operative day. The definitive anatomopathological analysis found the mass to be a benign GN. The patient is now 12 month after surgery, well and without signs of recurrence (no recurrence signs on MRI). Discussion GN are benign slow-growing lesions that arise from sympathetic ganglion cells and are considered to be the most benign tumor of the neuroblastoma group. GN are composed of mature ganglion cells, Schwann cells and nerve fibers (1). This rare tumor is most frequently found in childhood and adolescence and are extremely rare in adults. Arising from the neural crest, GN have the following distribution : posterior mediastinum (41.5% of cases), retroperitoneum (37.5%), adrenal gland (21%), and neck (8%) (9). The pre-sacral space is a extremely rare location, with only 21 described cases so far (3, 4, 5,
299 6, 7, 8). The physiopathology of GN remains obscure, some may arise de novo and others may mature from neuroblastoma or ganglioneuroblastoma either spontaneously or after radio-or chemotherapy (10, 11). No statistically significant difference in gender incidence exists (9). GN are commonly asymptomatic until they reach an important size. Most symptomatic patients have large tumors and present with constipation due to mass effect on the rectum or pain due to sacral root or lumbosacral plexus compression (3). Very rarely there may be systemic effects caused by excessive release of catecholamine analogs or vaso-active intestinal peptide (not assessed in our patient), resulting in diarrhea, hypertension or virilization. Most GN are therefore either incidental findings or diagnosed at an late stage of evolution (2). FDG-PET activity of peripheral neurogenic tumors has been assessed in patients with neurofibromatosis (12, 13) and SUVmax cut-off values of 1.8 and 2.5 proposed, to distinguish benign from malignant lesions. The FDG uptake we found (SUVmax 3.18) couldn't therefore be considerated as reassuring. FDG-PET plays an important role to detect, characterize and follow many tumors. Generally the degree of FDG uptake correlates with tumor grading, the higher the uptake the higher the histological grading. This is no absolute rule and some benign tumors might show elevated FDG uptake, as in the present case (13). No diagnostic tool, any radiologic imaging to biopsy can permit the definitive diagnosis of GN, therefore surgery remains the primary means of diagnosis and treatment. Complete resection should be obtained whenever possible, weighting the risks of leaving malignant neuroblastoma tissue arising from an heterogeneous tumor, against the risk of neurologic damage caused by complete excision of a tumor firmly adherent to the lumbosacral plexus in neurologically intact patients. Surgical resection is considered curative and no adjuvant chemoor radiotherapy is indicated. The surgical approach can be anterior, posterior (retroperitoneal) or combined, depending on the size and location of the tumor. The use of assisted laparoscopy, is in our opinion a very helpful tool to approach the surgically challenging presacral area. Although considered as benign, recurrence in GN has been described. Patients should therefore be followed at regular intervals to assess local recurrence (9). References 1. SHIMADA H., AMBRoS I. M., DEHNER L. P., HATA J., JoSHI VV., RoALD B. Terminology and Morphologic Criteria of Neuroblastic Tumors Recommendations by the International Neuroblastoma Pathology Committee. Cancer, 1999, 86 : 349-363. 2. LoNERGAN GJ., SCHWAB CM., SUAREz ES., CARLSoN CL. From the Archives of the AFIP Neuroblastoma, Ganglioneuroblastoma, and
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Dr. S. Holz RHMS Dept. of Surgery Belgium E-mail :
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