Effect of Omega-3 Supplementation in Patients With Smell Dysfunction Following Endoscopic Sellar and Parasellar Tumor Resection: A Multicenter Prospective Randomized Controlled Trial.

BACKGROUND: Endoscopic endonasal approaches pose the potential risk of olfactory loss. Loss of olfaction and potentially taste can be permanent and greatly affect patients' quality of life. Treatments for olfactory loss have had limited success. Omega-3 supplementation may be a therapeutic option with its effect on wound healing and nerve regeneration. OBJECTIVE: To evaluate the impact on olfaction in patients treated with omega-3 supplementation following endoscopic skull base tumor resection. METHODS: In this multi-institutional, prospective, randomized controlled trial, 110 patients with sellar or parasellar tumors undergoing endoscopic resection were randomized to nasal saline irrigations or nasal saline irrigations plus omega-3 supplementation. The University of Pennsylvania Smell Identification Test (UPSIT) was administered preoperatively and at 6 wk, 3 mo, and 6 mo postoperatively. RESULTS: Eighty-seven patients completed all 6 mo of follow-up (41 control arm, 46 omega-3 arm). At 6 wk postoperatively, 25% of patients in both groups experienced a clinically significant loss in olfaction. At 3 and 6 mo, patients receiving omega-3 demonstrated significantly less persistent olfactory loss compared to patients without supplementation (P = .02 and P = .01, respectively). After controlling for multiple confounding variables, omega-3 supplementation was found to be protective against olfactory loss (odds ratio [OR] 0.05, 95% CI 0.003-0.81, P = .03). Tumor functionality was a significant independent predictor for olfactory loss (OR 32.7, 95% CI 1.15-929.5, P = .04). CONCLUSION: Omega-3 supplementation appears to be protective for the olfactory system during the healing period in patients who undergo endoscopic resection of sellar and parasellar masses.

Evidence-Based Optimization of Post-Treatment Surveillance for Skull Base Chordomas Based on Local and Distant Disease Progression.

BACKGROUND: There are no guidelines regarding post-treatment surveillance specific to skull base chordomas. OBJECTIVE: To determine an optimal imaging surveillance schedule to detect both local and distant metastatic skull base chordoma recurrences. METHODS: A retrospective review of 91 patients who underwent treatment for skull base chordoma between 1993 and 2017 was conducted. Time to and location of local and distant recurrence(s) were cataloged. Existing chordoma surveillance recommendations (National Comprehensive Cancer Network [NCCN], London and South East Sarcoma Network [LSESN], European Society for Medical Oncology [ESMO], Chordoma Global Consensus Group [CGCG]) were applied to our cohort to compare the number of recurrent patients and months of undiagnosed tumor growth between surveillances. These findings were used to inform the creation of a revised imaging surveillance protocol (MD Anderson Cancer Center Chordoma Imaging Protocol [MDACC-CIP]), presented here. RESULTS: Thirty-four patients with 79 local/systemic recurrences met inclusion criteria. Mean age at diagnosis and follow-up time were 45 yr and 79 mo, respectively. The MDACC-CIP imaging protocol significantly reduced the time to diagnosis of recurrence compared with the LSESN and CGCG/ESMO imaging protocols for surveillance of local disease with a cumulative/average of 576/16.9 (LSESN), 336/9.8 (CGCG), and 170/5.0 (MDACC-CIP) months of undetected growth, respectively. The NCCN and MDACC-CIP guidelines for distant metastatic surveillance identified a cumulative/average of 65/6.5 and 51/5.1 mo of undetected growth, respectively, and were not significantly different. CONCLUSION: The MDACC-CIP for skull base chordoma accounts for recurrence trends unique to this disease, including a higher rate of leptomeningeal spread than sacrococcygeal primaries, resulting in improved sensitivity and prompt diagnosis.

Prospective analysis of neuropsychological deficits following resection of benign skull base meningiomas.

OBJECTIVE Resection of skull base tumors is challenging. The introduction of alternative treatment options, such as radiotherapy, has sparked discussion regarding outcome in terms of quality of life and neuropsychological deficits. So far, however, no prospective data are available on this topic. METHODS A total of 58 patients with skull base meningiomas who underwent surgery for the first time were enrolled in this prospective single-center trial. The average age of the patients was 56.4 ± 12.5 years. Seventy-nine percent of the tumors were located within the anterior skull base. Neurological examinations and neuropsychological testing were performed at 3 time points: 1 day prior to surgery (T1), 3-5 months after surgery (T2), and 9-12 months after surgery (T3). The average follow-up duration was 13.8 months. Neuropsychological assessment consisted of quality of life, depression and anxiety, verbal learning and memory, cognitive speed, attention and concentration, figural memory, and visual-motor speed. RESULTS Following surgery, 23% of patients showed transient neurological deficits and 12% showed permanent new neurological deficits with varying grades of manifestation. Postoperative quality of life, however, remained stable and was slightly improved at follow-up examinations at T3 (60.6 ± 21.5 vs 63.6 ± 24.1 points), and there was no observed effect on anxiety and depression. Long-term verbal memory, working memory, and executive functioning were slightly affected within the first months following surgery and appeared to be the most vulnerable to impairment by the tumor or the resection but were stable or improved in the majority of patients at long-term follow-up examinations after 1 year. CONCLUSIONS This report describes the first prospective study of neuropsychological outcomes following resection of skull base meningiomas and, as such, contributes to a better understanding of postoperative impairment in these patients. Despite deterioration in a minority of patients on subscales of the measures used, the majority demonstrated stable or improved outcome at follow-up assessments.

[Asymptomatic skull base metastases: clinical course and therapeutic alternatives]. / Metastasis asintomaticas de la base craneal: evolucion clinica y alternativas terapeuticas.

INTRODUCTION: Skull base metastases (SBM) are an infrequent and late type of cancer progression that are associated to poor prognosis. Its clinical manifestations may be grouped in five clinical syndromes and radiotherapy is its more frequent treatment. Because of the improvement in imaging tests and the close follow up of cancer patients, SBM can be diagnosed incidentally. In this group the best option of treatment has not been established. AIM: To analyze the clinical features and outcomes of patients with SBM diagnosed incidentally. PATIENTS AND METHODS: Between January 2012 and December 2015, 31 patients with diagnoses of SBM from solid primary tumor were reviewed. RESULTS: SBM were diagnosed due to skull base syndromes (n = 24) or incidentally (n = 7). Symptomatic patients were treated with radiotherapy. Patients diagnosed incidentally remained without symptoms of craneal base involvement during the follow up, although they frequently had other types of intracranial progression. A statistically significant difference in survival was observed between symptomatic and asymptomatic patients (p = 0.001). CONCLUSIONS: The incidentally diagnosed SBM were frequently associated to other types of intracranial progression, limiting the options of treatment.

TITLE: Metastasis asintomaticas de la base craneal: evolucion clinica y alternativas terapeuticas.Introduccion. Las metastasis sintomaticas de la base craneal (MBC) son una progresion infrecuente, tardia y de mal pronostico en pacientes con tumores solidos. Sus manifestaciones clinicas pueden agruparse en cinco sindromes caracteristicos, y su tratamiento mas frecuente es la radioterapia. Gracias a los progresos tecnologicos en las pruebas de imagen y al seguimiento estrecho de los pacientes con cancer, las MBC pueden diagnosticarse incidentalmente. En este subgrupo no se conoce la evolucion clinica ni se ha establecido la mejor modalidad de tratamiento. Objetivo. Analizar las caracteristicas clinicas y la evolucion de los pacientes diagnosticados incidentalmente de MBC. Pacientes y metodos. Entre enero de 2012 y diciembre de 2015, 31 pacientes con una neoplasia solida diagnosticados de MBC fueron valorados por nuestro servicio. Resultados. Las MBC se diagnosticaron por la presencia de un sindrome de base craneal (n = 24) o incidentalmente (n = 7). Los pacientes sintomaticos fueron tratados con radioterapia. Todos los pacientes diagnosticados incidentalmente permanecieron sin sintomas relacionados con la afectacion de la base craneal hasta la fecha del fallecimiento, aunque frecuentemente presentaron de forma concomitante otros tipos de progresion intracraneal de mal pronostico. Se observo una diferencia estadisticamente significativa en la supervivencia a favor de los pacientes sintomaticos (p = 0,001). Conclusiones. Las MBC diagnosticadas incidentalmente se asociaron frecuentemente a otros tipos de progresion intracraneal, limitando las opciones terapeuticas.

(125)I interstitial brachytherapy for the treatment of myoepithelial carcinoma of the oral and maxillofacial region.

PURPOSE: This study evaluated the treatment of myoepithelial carcinoma (MC) of the oral and maxillofacial region with radioactive iodine ((125)I) seed implantation. METHODS AND MATERIALS: Twenty-seven patients with MC in the oral and maxillofacial region were treated with (125)I seed implantation between March 2006 and October 2012. Thirteen of the 27 patients (8/8 patients with primary disease and 5/19 patients with recurrent disease) were treated on an adjuvant setting after resections, and the other 14 patients were treated by brachytherapy after a recurrence precluding a surgical resection for salvage. The sites of the MC were the parotid for 18 patients, oral cavity for 2 patients, and base of skull for 7 patients. Recurrence-free survival (RFS), overall survival (OS) rates, and side effects were retrospectively reviewed. RESULTS: Patients were followed for 6-105 months (median 37 months). The 3- and 5-year RFS rates were 51.9% and 46.1%, respectively. The 3- and 5-year OS rates were 68.6% and 51.5%, respectively. The OS and RFS were significantly better among the 8 patients treated upfront in comparison with the 19 patients treated for salvage at relapse. The OS was worst for the 7 patients with base of skull region disease. No severe complications were observed during followup. CONCLUSIONS: This study showed (125)I brachytherapy is a feasible and effective modality for the treatment of MC. These findings should be interpreted cautiously due to the small number of patients and the relatively short followup.

Outcomes of endonasal endoscopic dacryocystorhinostomy after maxillectomy in patients with paranasal sinus and skull base tumors.

Maxillectomy followed by radiotherapy and/or chemotherapy can result in lacrimal blockage and the need for subsequent dacryocystorhinostomy (DCR). Endonasal endoscopic DCR, as opposed to external DCR, allows better accuracy and leaves no scar. To date no report was published regarding the results of endoscopic DCR in these patients. The current study presents a retrospective review of all patients with paranasal and skull base tumors who developed nasolacrimal duct blockage after ablative maxillectomy with or without radiotherapy and/or chemotherapy and underwent endonasal endoscopic DCR between January 2006 and October 2012 in a tertiary reference medical center. According to our results, ten patients underwent 11 subsequent endonasal endoscopic DCR. There were 6 men and 4 women with a median age of 55 years (range, 19-81 years); four suffered from benign tumors and six had malignant tumors. All underwent maxillectomy. Six received high-dose radiotherapy. Time interval between primary ablative surgery and endonasal endoscopic DCR was 18 months (range, 7-118 months). Silicone stents were removed after median period of 11 weeks (range, 1-57 weeks). Nine out of ten patients experienced symptomatic improvement following one endonasal endoscopic DCR. One patient had recurrent epiphora and underwent a successful endonasal endoscopic revision DCR. In conclusion, endonasal endoscopic DCR in patients with paranasal and skull base tumors, who previously underwent maxillectomy, is generally successful and not associated with a high rate of complications or failure. Moreover, our findings may suggest that silicone stents can be removed shortly after the operation with high success rate.

Shortening the learning curve in endoscopic endonasal skull base surgery: a reproducible polymer tumor model for the trans-sphenoidal trans-tubercular approach to retro-infundibular tumors.

BACKGROUND: Endoscopic endonasal skull base surgery attracts an increasing number of young neurosurgeons. This recent technique requires specific technical skills for the approaches to non-pituitary tumors (expanded endoscopic endonasal surgery). Actual residents' busy schedules carry the risk of compromising their laboratory training by limiting significantly the dedicated time for dissections. OBJECTIVE: To enhance and shorten the learning curve in expanded endoscopic endonasal skull base surgery, we propose a reproducible model based on the implantation of a polymer via an intracranial route to provide a pathological retro-infundibular expansive lesion accessible to a virgin expanded endoscopic endonasal route, avoiding the ethically-debatable need to hundreds of pituitary cases in live patients before acquiring the desired skills. METHODS: A polymer-based tumor model was implanted in 6 embalmed human heads via a microsurgical right fronto-temporal approach through the carotido-oculomotor cistern to mimic a retro-infundibular tumor. The tumor's position was verified by CT-scan. An endoscopic endonasal trans-sphenoidal trans-tubercular trans-planum approach was then carried out on a virgin route under neuronavigation tracking. RESULTS: Dissection of the tumor model from displaced surrounding neurovascular structures reproduced live surgery's sensations and challenges. Post-implantation CT-scan allowed the pre-removal assessment of the tumor insertion, its relationships as well as naso-sphenoidal anatomy in preparation of the endoscopic approach. CONCLUSION: Training on easily reproducible retro-infundibular approaches in a context of pathological distorted anatomy provides a unique opportunity to avoid the need for repetitive live surgeries to acquire skills for this kind of rare tumors, and may shorten the learning curve for endoscopic endonasal surgery.

Preoperative and postoperative neurological, neuropsychological and behavioral impairment in children with posterior cranial fossa astrocytomas and medulloblastomas: the role of the tumor and the impact of the surgical treatment.

INTRODUCTION: The aim of the present study was to prospectively investigate if a correlation might exist between preoperative and postoperative neurological conditions, neuroradiological/intraoperative findings and results of a complete neuropsychological evaluation in children with posterior fossa medulloblastomas and astrocytomas. MATERIALS AND METHODS: Of the 65 children admitted at the Pediatric Neurosurgery of the UCSC of Rome between January 2005 and October 2009, 41 were selected; the only two exclusion criteria were represented by age under 24 months and severe neurological conditions, seen that in both cases it would not have been a possible reliable evaluation. All children underwent a preoperative and immediate postoperative complete MR study. Hydrocephalus was graded on the Evans score; brainstem infiltration was defined on intraoperative findings. Neuropsychological assessment consisted of a battery of tests tailored on the patient's age, cognitive level, and level of cooperation. Post operative neuropsychological evaluation was performed at a mean time of 2.5 min (2 mos, max 4.5 mos) from the operation, before any eventually needed adjuvant treatment (i.e., chemotherapy, radiotherapy). RESULTS: Concerning neurological status, we found a statistically significant relation between the presence of oculomotor impairment and both verbal fluency deficits (p = 0.044) and imagery disorders (p = 0.03); also, the presence of ataxia/dysmetria was significantly correlated to attention dysfunction (p = 0.01) and, more tightly, to planning dysfunction (p = 0.006). For neuroradiological/intraoperative features, Intelligence Quotient (IQ) impairment was significantly correlated to the intraoperative evidence of tumor infiltration of the brainstem (p = 0.003), a severe hydrocephalus at diagnosis (p = 0.001) and the histological diagnosis of medulloblastoma (MB) (p = 0.002). For selective skills, a significant correlation was found between linguistic processing deficits and the evidence of dentate nuclei infiltration (blindly defined on MR); procedural memory defects and imagery disorders related to the severity of the hydrocephalus (p = 0.02), infiltration of the brain stem (p = 0.01) and a histological diagnosis of MB (p = 0.01). After surgery no patient showed a worsening of his/her cognitive profile; the relationships between clinical, intraoperative, and radiological findings were substantially confirmed. DISCUSSION: Our results support the hypothesis that when present, neuropsychological impairment is already present at diagnosis and that the most statistically significant factors, which might be related with cognitive deficits in the preoperative as well as in the postoperative period, are tumor infiltration of the brainstem, the severity of hydrocephalus, and a histological diagnosis of MB.

Maxillary removal and reinsertion: a favorable approach for extensive anterior cranial base tumors.

OBJECTIVE: To analyze the long-term results and the complications related to an expanded series of maxillary removal and reinsertion (MRRI) with 18-year surgical experience. STUDY DESIGN: Case series with chart review of the MRRI patients in the last 18 years. SETTING: The Ohio State University Comprehensive Cancer Center, James Cancer Hospital and Solove Research Institute. SUBJECTS AND METHODS: Seventy-eight patients who underwent MRRI from February 1990 through February 2007. The median age was 51 years (range 11-77 yrs). Sixty-two (80%) patients had malignant lesions. RESULTS: MRRI has been successfully completed in all 78 patients, with no intraoperative mortality. The most commonly encountered malignant neoplasm was squamous cell cancer (40.3%), followed by esthesioneuroblastoma (24.1%), adenoid cystic cancer (8%), and other neoplasms (27.4%). The most commonly encountered postoperative complication was diplopia, which has persisted in five (6.4%) patients in the short-term and in three (4%) patients in the long-term follow-up. Nasal asymmetry was the most common long-term complication (17.9%), followed by plate-associated problems (10.2%) and midface asymmetry (10.2%). Overall five-year survival for the patients with squamous cell carcinoma was 62 percent. CONCLUSION: MRRI is a favorable surgical technique for the treatment of anterior cranial base (ACB) tumors in adults and even in children. It improves operative morbidity by preserving both function and form of the maxillary region and gives excellent exposure to ACB.

Quantitative analysis of exposure of staged orbitozygomatic and retrosigmoid craniotomies for lesions of the clivus with supratentorial extension.

OBJECTIVE: A two-stage approach using orbitozygomatic (OZ) and retrosigmoid (RS) craniotomies is one option for the management of petroclival lesions with supratentorial extension. The goal of this study was to investigate the supratentorial and infratentorial exposures of the clivus obtained through this staged approach. METHODS: Formalin-fixed, silicon-injected specimens underwent stereotactic imaging. Six paired OZ and RS craniotomies were performed. Neuronavigation was used to determine the areas and limits of exposure and to plot these areas on three-dimensional reconstructions of the skull base. RESULTS: The mean area of exposure of the parasellar region and clivus through the OZ craniotomy was 640 +/- 75 mm. Visualization of the parasellar region, cavernous sinus, and upper cranial nerves was achieved. The ventral brainstem corresponding to the cranial quarter of the clivus was visualized. The mean area of exposure of the clivus and petrous bone through the RS was 1930 +/- 250 mm. In the cranial quarter of the clivus, there was a small region of overlap in exposure between the two craniotomies. The limits of exposure are described. CONCLUSION: OZ and RS craniotomies provide complementary exposure with limited redundancy. Significant visualization of the parasellar region, clivus, and surrounding bony landmarks is obtained. The primary limitation is exposure of the contralateral half of Zones II and III of the clivus. This strategy represents a reasonable option for accessing paracentral petroclival lesions with a supratentorial extension.

[Facial nerve motor evoked potentials elicited by transcranial electrical stimulation for intraoperative monitoring].

OBJECTIVE: To determine whether monitoring facial nerve motor evoked potentials (FNMEPs) elicited by transcranial electrical stimulation during skull base tumor surgery is useful for predicting facial nerve outcome. METHODS: We analyzed FNMEP findings in 31 patients with skull base tumor. Surgery was performed twice in 2 of the 31 patients because of tumor regrowth. FNMEP monitoring was conducted 33 times in the present study. Corkscrew electrodes positioned at C3 or C4 and Cz were used to deliver supramaximal stimuli (140-550V). FNMEPs were recorded from the orbicularis oculi and oris muscles. Correlation between the final-to-baseline FNMEP ratio and postoperative facial nerve function (House & Brackmann grade) was examined. RESULTS: Valid FNMEPs were obtained in 26 of the 33 (78.8%) recordings from the orbicularis oculi muscle and in 31 of the 33 (93.9%) recordings from the orbicularis oris muscle. Facial nerve function correlated significantly with the FNMEP ratios in the orbicularis oculi (r = -0.52 N=26, p < 0.01) and orbicularis oris (r = -0.60, N=31, p < 0.001) muscles. An FNMEP ratio of -50% consistently predicted immediate postoperative facial palsy, although the degree of palsy differed among the patients. CONCLUSIONS: Intraoperative FNMEP monitoring is useful for predicting facial nerve function after skull base surgery.

Reconstruction of ablative skull base defects in the pediatric population.

BACKGROUND: Neoplasms of the skull base are rare in children and require a multidisciplinary approach. Surgical defects are often large and cause significant functional, aesthetic, and psychological issues. The authors present their experience with reconstruction of the anterior and lateral skull base in the pediatric population. METHODS: The authors conducted a retrospective review at a comprehensive cancer center. RESULTS: Between January of 1993 and February of 2005, 10 children and adolescents underwent surgical resection of a skull base tumor followed by reconstruction of the skull base. Patients ranged in age from 6.4 to 17.9 years (median, 11.8 years). Four patients had rhabdomyosarcoma, and one each had spindle cell sarcoma, chondrosarcoma, liposarcoma, malignant fibrous histiocytoma, mucoepidermoid carcinoma, and neurofibromatosis. Surgical defects involved the anterior skull base in three patients, the infratemporal fossa in three patients, both the anterior and middle cranial fossae in three patients, and the temporal bone in one patient. Fourteen flap procedures were performed in these patients-11 after tumor resection and three in a delayed fashion to promote improved functional and aesthetic outcomes. Complications occurred in three patients, and there was one case of flap loss. CONCLUSIONS: Skull base reconstruction may be reliably and successfully accomplished in children and adolescents using soft-tissue free flaps or regional flaps. Full rehabilitation, including bony reconstruction and prosthetic rehabilitation, may be accomplished as craniofacial development plateaus in adolescence.

Phosphaturic mesenchymal tumor with symptoms related to osteomalacia that appeared one year after tumorectomy.

A 45-year-old man was admitted to our hospital because of bone pain and hypophosphatemia. He had undergone surgery 2 years previously for a "benign unclassified mesenchymal tumor" in the skull, but there were no clinical symptoms related to osteomalacia. His laboratory examination revealed low serum phosphate, high alkaline phosphatase, and normal calcium levels. The diagnosis of tumor-induced osteomalacia due to phosphaturic mesenchymal tumor mixed connective tissue variant (PMTMCT) was made by re-examining the pathologic specimens. Oral supplementation with phosphate and 1-25-dihydroxyvitamin D relieved his clinical symptoms and laboratory values returned to normal. However, subcutaneous administration of octreotide had no clinical effect. Clinicians and pathologists should be aware of the existence of PMTMCT especially nonphosphaturic or asymptomatic variants of this disorder.

Evolving role of skullbase surgery for patients with low and high grade malignancies.

Malignancy involving the skull base remains a formidable management challenge. Advances and refinements in diagnostic imaging, instrumentation, microvascular reconstruction, and an improved overall appreciation of the anatomy of the skullbase have extended the boundaries of tumor resectability and in some cases, obviated the need for adjuvant therapies. Successful management of high-grade malignancy however, requires a carefully constructed multi-modal treatment plan to maximize patient outcome. Over the course of an 11-year period, 259 patients with skullbase malignancies were treated by the author in the setting of a tertiary care comprehensive cancer center. All patients were evaluated by a multidisciplinary team experienced in the assessment and treatment of skullbase malignancy. Management paradigms were constructed and treatment based on categorization into low or high-grade malignancy was recommended and undertaken. This manuscript discusses this patient population and the outcome of the management paradigms that were constructed. Differences in outcome based on the characterization of malignancies as either low or high grade is discussed. Complications of treatment and patient reported quality of life outcomes are reviewed.

Maffucci's syndrome associated with a cranial base chondrosarcoma: case report and literature review.

OBJECTIVE AND IMPORTANCE: Our objective was to study the diagnosis and management of this rare condition. A review of the literature concerning chondrosarcomas related to Maffucci's syndrome is reported. Cause and management are discussed. CLINICAL PRESENTATION: We report a case of Maffucci's syndrome associated with a cranial base chondrosarcoma. To our knowledge, only five similar cases have been reported in the literature. The differential diagnosis between Ollier's disease and Maffucci's syndrome and the causes of these conditions are not clear. INTERVENTION: An 18-year-old female patient presented with a giant tumor involving the posterior fossa, clivus, middle fossa, and cavernous sinus. The lesion could be totally removed through a transzygomatic approach. The histological diagnosis was chondrosarcoma. It was confirmed by immunohistochemical studies. There were no postoperative complications. CONCLUSION: Maffucci's syndrome is a rare clinical condition that presents difficulties concerning its diagnosis and management. It is characterized by the presence of multiple enchondromas and cutaneous hemangiomas. Intracranial chondrosarcomas may be associated with this syndrome. Immunohistochemical studies are necessary to differentiate chondrosarcomas from chordomas. The treatment of choice for cranial base chondrosarcomas is total removal of the lesion. Total removal may be very difficult to achieve because of the involvement of neurovascular structures. Alternative therapies, such as proton beam radiosurgery, should be considered. In this case, radical removal of the tumor was possible using a transzygomatic approach. Gross total removal of large cranial base chondrosarcomas is possible, but a longer follow-up period is necessary to ascertain that radical resection was achieved.

Chondrosarcoma of the skull base: CT, MR and pathological features.

We report on CT and MR image findings of a skull base chondrosarcoma. Chondroid mineralisation, a histological feature of chondrosarcoma, can be recognised on CT and is, together with the off-midline position of the tumour, the most characteristic finding. Differentiation is usually made by histological and immunocytochemical staining. Surgery, proton radiation therapy and stereotactic single high-dose irradiation have been used to treat patients with chondrosarcoma. It is worth mentioning that it was likely that the chondrosarcoma in our patient represented a malignant degeneration of an enchondroma that had been resected 30 years earlier.