Diffusion-Weighted Imaging of Skull Lesions

Diffusion-weighted imaging can increase the conspicuity of skull lesions and be applied toward noninvasive differentiation of malignant from benign lesions. Malignant skull lesions generally display lower diffusivity than benign lesions, although there are exceptions, and clinical parameters and conventional imaging modalities should also be considered in the evaluation of skull lesions. Nevertheless, in some instances diffusion-weighted imaging (DWI) can be used for problem solving when conventional imaging features are indeterminate, such as with skull base involvement by nasopharyngeal carcinoma versus osteomyelitis. In addition, DWI may be useful for monitoring treatment effects. The use of readout segmented technique, parallel imaging, multishot acquisition, turbo spin-echo DWI, diffusion tensor imaging, and higher field strengths can improve image quality. The feasibility of implementing DWI for characterizing skull lesions, the DWI findings of benign and malignant skull lesions, and technical considerations are discussed in this article.     

Surgical pathology of the skull base: a 7-year experience

A significant diversity of tissue types interface at the base of the skull and contribute to the diagnostic challenges of skull base surgical pathology. Advances in surgical technique now permit biopsy and resection of lesions previously termed "inoperable." Retrospective review was made of all pathology specimens from skull base surgeries performed at the University of California Davis Medical Center from 1990 to 1996. Surgical biopsies and resections were performed on 186 patients who had 33 distinctive diagnoses. Any preoperative biopsy or tissue from referring institutions was reviewed prior to skull base surgery. One hundred eighteen patients had benign lesions, the most frequent of which were pituitary adenoma (55) and acoustic neuroma (27). Other benign lesions included angiofibroma, meningioma, fibrous dysplasia, and paraganglioma. Sixty-eight patients had malignant tumors, 32 of which were squamous cell earcinoma. Other malignancies included salivary carcinomas, basal cell carcinoma, neuroblastoma, melanoma, and several sarcomas. Unexpected findings were two metastatic carcinomas and five inflammatory lesions. Nearly 1500 intraoperative consultations were performed to establish resection margins and less commonly to confirm the diagnosis. The discrepancy rate between the intraoperative and final diagnosis was 1.8%. Immunohistochemistry and/or electron microscopy was utilized in 44% of the specimens to confirm the diagnosis. Surgical pathology is an essential ingredient to a successful skull base surgery program. Pathologists are involved in both pre- and intraoperative decisions. The diversity of lesions that arise from the skull base often has overlapping histologies that require careful attention to morphology and the use of ancillary studies for accurate diagnosis. The need for frequent intraoperative interpretations contributes to the significant challenge for the surgical pathologist.     

Surgical Pathology of the Skull Base: A 7-Year Experience

A significant diversity of tissue types interface at the base of the skull and contribute to the diagnostic challenges of skull base surgical pathology. Advances in surgical technique now permit biopsy and resection of lesions previously termed “inoperable.” Retrospective review was made of all pathology specimens from skull base surgeries performed at the University of California Davis Medical Center from 1990 to 1996. Surgical biopsies and resections were performed on 186 patients who had 33 distinctive diagnoses. Any preoperative biopsy or tissue from referring institutions was reviewed prior to skull base surgery. One hundred eighteen patients had benign lesions, the most frequent of which were pituitary adenoma (55) and acoustic neuroma (27). Other benign lesions included angiofibroma, meningioma, fibrous dysplasia, and paraganglioma. Sixty-eight patients had malignant tumors, 32 of which were squamous cell earcinoma. Other malignancies included salivary carcinomas, basal cell carcinoma, neuroblastoma, melanoma, and several sarcomas. Unexpected findings were two metastatic carcinomas and five inflammatory lesions. Nearly 1500 intraoperative consultations were performed to establish resection margins and less commonly to confirm the diagnosis. The discrepancy rate between the intraoperative and final diagnosis was 1.8%. Immunohistochemistry and/or electron microscopy was utilized in 44% of the specimens to confirm the diagnosis. Surgical pathology is an essential ingredient to a successful skull base surgery program. Pathologists are involved in both pre- and intraoperative decisions. The diversity of lesions that arise from the skull base often has overlapping histologies that require careful attention to morphology and the use of ancillary studies for accurate diagnosis. The need for frequent intraoperative interpretations contributes to the significant challenge for the surgical pathologist.     

A comprehensive algorithm for anterior skull base reconstruction after oncological resections.

Objective: To present our method for anterior skull base reconstruction after oncological resections. Methods: One hundred nine patients who had undergone 120 anterior skull base resections of tumors (52 malignant [43%], 68 benign [57%]) via the subcranial approach were studied. Limited dural defects were closed primarily or reconstructed using a temporalis fascia. Large anterior skull base defects were reconstructed by a double-layer fascia lata graft. A split calvarial bone graft, posterior frontal sinus wall, or three-dimensional titanium mesh were used when the tumor involved the frontal, nasal, or orbital bones. A temporalis muscle flap was used to cover the orbital socket for cases of eye globe exenteration, and a rectus abdominis free flap was used for subcranial-orbitomaxillary resection. Pericranial flap wrapping of the frontonaso-orbital segment was performed to prevent osteoradionecrosis if perioperative radiotherapy was planned. Results: The incidence of cerebrospinal fluid (CSF) leak, intracranial infection, and tension pneumocephalus was 5%. Histopathological and immunohistochemical analysis of fascia lata grafts in reoperated patients (n = 7) revealed integration of vascularized fibrous tissue to the graft and local proliferation of a newly formed vascular layer embedding the fascial sheath. Conclusion: A double-layer fascial graft alone was adequate for preventing CSF leak, meningitis, tension pneumocephalus, and brain herniation. We describe a simple and effective method of anterior skull base reconstruction after resections of both malignant and benign tumors.     

Transmandibular exposure of the skull base

The combined transmandibular-transcervical approach to the skull base ensures a wide field exposure to the lateral and midline compartments of the middle cranial fossa with attendant vascular control. Splitting the lip and mandible in the midline and dividing the floor of the mouth structures along the lateral border of the tongue exposes the parapharyngeal space, infratemporal fossa (lateral compartment), and clivus, nasopharynx, and cervical spine (midline compartment). A variety of benign and malignant intracranial and extracranial skull base lesions have been treated using this approach.     

Lateral Skull Base Surgery: The Otology Group Experience

Lateral skull base surgery has remained the surgical frontier of new developments in the treatment of lesions heretofore difficult to access. Examination of surgical results stimulates technical innovation and provides an intervention risk-benefit ratio assessment for particular lesions useful in management planning. With this in mind, we report the updated collective experience with lateral skull base surgery at the Otology Group over the past 20 years. Two hundred ninety-eight patients underwent surgical intervention for lateral skull base lesions. In 81 patients these lesions were malignant; in 217, benign. Of the benign lesions, 165 were glomus tumors: 139 glomus jugulare, 19 glomus vagale, and 7 glomus tympanicum. The remainder comprised 21 menigniomas, 14 neuromas, two neurofibromas, and a small group of much rarer entities. The philosophy of surgical approach, results, and follow-up are discussed.     

Lateral skull base surgery: the otology group experience

Lateral skull base surgery has remained the surgical frontier of new developments in the treatment of lesions heretofore difficult to access. Examination of surgical results stimulates technical innovation and provides an intervention risk-benefit ratio assessment for particular lesions useful in management planning. With this in mind, we report the updated collective experience with lateral skull base surgery at the Otology Group over the past 20 years. Two hundred ninety-eight patients underwent surgical intervention for lateral skull base lesions. In 81 patients these lesions were malignant; in 217, benign. Of the benign lesions, 165 were glomus tumors: 139 glomus jugulare, 19 glomus vagale, and 7 glomus tympanicum. The remainder comprised 21 menigniomas, 14 neuromas, two neurofibromas, and a small group of much rarer entities. The philosophy of surgical approach, results, and follow-up are discussed.     

Ameloblastic carcinoma arising from anterior skull base.

Ameloblastic carcinoma (AC) is an aggressive malignant epithelial odontogenic tumor. It may appear de novo or originate from a pre-existing ameloblastoma or odontogenic cyst. To our knowledge, an AC that originates from the anterior skull base has not been reported before in the English literature. We report a case of an AC that originated from the anterior skull base and invaded the dura of the anterior fossa and discuss its clinical course and treatment.     

Surgical management of parapharyngeal space masses

BACKGROUND: We sought to examine surgical techniques used to remove parapharyngeal space (PPS) masses. METHODS: This retrospective search was conducted from 1980 to 2003. Age, sex, diagnosis, surgical approach, complications, and outcome were collected. RESULTS: One hundred sixty-six PPS masses were identified: 21 (12.7%) were malignant, 145 (87.3%) were benign, 76 (45.8%) were vascular, and 69 (41.6 %) involved the skull base. Transcervical techniques were used in all cases. Removing the styloid and its musculature and level II lymphadenectomies enhanced exposure for vascular and skull base tumors. Thirty transcervical-transmastoid dissections (20.4%) facilitated removal of vascular skull base tumors. To identify the facial nerve, 20 transparotid-transcervical approaches (13.6%) were performed. Three mandibulotomies (2.0%) were required for internal carotid artery involvement. Expected neurologic sequelae resulted from cranial nerve involvement by tumor. Three patients (2.0%), all presenting with recurrent cancer, had local recurrences. CONCLUSION: Careful patient assessment and surgical techniques allow the oncologically safe removal of benign, vascular, and skull base PPS tumors.     

Clinical analysis of malignant meningiomas

It seems generally accepted that meningiomas are benign tumors, and that malignant meningiomas are not common. The pathological criteria for judging whether meningiomas are malignant or not are controversial. Hemangiopericytic type, high cellularity, brain invasion, high mitotic rate, necrotic foci, and papillary type are regarded as histological characteristics of malignant meningiomas. Of a series of 105 patients with surgically treated meningioma, 25 patients demonstrated malignant characteristics (24%). The overall recurrence rate in our patients was 14%. The incidence of recurrence in 25 patients with pathologically malignant characteristics, and recurrence in 80 patients with pathologically benign characteristics were 32% and 9%, respectively. In comparison with benign meningiomas, recurrent factors in malignant ones included Simpson grade II operation, attachment of skull base, and no radiation-therapy. In conclusion, our criteria for malignant meningiomas have proved to be acceptable, and these cases should be treated with radiation therapy after surgery.     

Malignant PEComa of the skull base

Perivascular epithelioid cell tumors (PEComas) are rare, usually benign lesions comprising a family of neoplasms including angiomyolipoma, lymphangioleiomyomatosis, clear cell "sugar" tumors, and clear cell myomelanocytic tumors. This report describes an apparent case of a malignant PEComa of the skull base in a 49-year-old woman, a previously undescribed location for this lesion.     

The use of the facial translocation technique in the management of tumors of the paranasal sinuses and skull base.

OBJECTIVE: We sought to assess the efficacy of facial translocation in the management of tumors of the skull base and paranasal sinuses. STUDY DESIGN AND SETTING: From July 1993 to December 1999, 75 patients, aged 3 to 102 years old, underwent facial translocation. Thirty-three (44%) patients also underwent a combined neurosurgical procedure. Nineteen (25%) had previous surgery. These patients were followed up to 6 years. RESULTS: There were 21 benign and 54 malignant tumors. There were no perioperative deaths. The morbidity rate was 31%. Of the 54 patients with malignant tumors, the actuarial 3-year survival rate was 59%, whereas the local control rate was 54%. CONCLUSION: The facial translocation technique offers favorable exposure of the critical zones of the anterior and middle cranial base, thus facilitating extensive resection and reconstruction. SIGNIFICANCE: This study demonstrates that facial translocation is one of the best surgical approaches to the skull base.     

Anterior skull base surgery for secondary malignancies in retinoblastoma survivors: report of two cases

With the improved survival rate of patients with retinoblastoma, the incidence of second malignancies has become substantial. We had two retinoblastoma survivors with secondary malignancies in the naso-ethmoidal complex, one a 21-year-old man with anaplastic carcinoma and the other a 16-year-old girl with malignant fibrous histiocytoma. They underwent repeated craniofacial surgery. Secondary malignancies arising at the nose and ethmoidal cells often invade the anterior skull base. The introduction of skull base surgery has provided wider surgical margins and increased the resultant likelihood of cure. Both patients have so far shown no evidence of recurrence.     

Anterior Skull Base Surgery for Secondary Malignancies in Retinoblastoma Survivors: Report of Two Cases

With the improved survival rate of patients with retinoblastoma, the incidence of second malignancies has become substantial. We had two retinoblastoma survivors with secondary malignancies in the naso-ethmoidal complex, one a 21-year-old man with anaplastic carcinoma and the other a 16-year-old girl with malignant fibrous histiocytoma. They underwent repeated craniofacial surgery. Secondary malignancies arising at the nose and ethmoidal cells often invade the anterior skull base. The introduction of skull base surgery has provided wider surgical margins and increased the resultant likelihood of cure. Both patients have so far shown no evidence of recurrence.     

Harvey Cushing's Approaches to Tumors in His Early Career: From the Skull Base to the Cranial Vault

In this report, we review Dr. Cushing's early surgical cases at the Johns Hopkins Hospital, revealing details of his early operative approaches to tumors of the skull base and cranial vault. Following Institutional Review Board approval, and through the courtesy of the Alan Mason Chesney Archives, we reviewed the Johns Hopkins Hospital surgical files from 1896 to 1912. Participants included four adult patients and one child who underwent surgical resection of bony tumors of the skull base and the cranial vault. The main outcome measures were operative approach and condition recorded at the time of discharge. The indications for surgery included unspecified malignant tumor of the basal meninges and temporal bone, basal cell carcinoma, osteoma of the posterior skull base, and osteomas of the frontal and parietofrontal cranial vault. While Cushing's experience with selected skull base pathology has been previously reported, the breadth of his contributions to operative approaches to the skull base has been neglected.     

经颅径路行前颅底肿瘤切除并双重组织瓣重建颅底一例

目的寻求更好的贯穿性颅底肿瘤切除和颅底重建手术方法。方法2004年11月收治1例贯穿于前颅底的复发性腺样囊性癌男性患者,年龄49岁。MRI提示鼻腔及上颌窦内占位复发并经左眶内侧侵入颅内。采用改良经颅径路,完整切除可见肿瘤,并采用带蒂骨膜颞肌筋膜瓣15cm×10cm及带蒂帽状腱膜额肌瓣10cm×6cm,双重组织瓣重建颅底。结果术后患者创口期愈合,未出现感染、脑脊液鼻漏等并发症,10d出院。随访8个月未见肿瘤复发,面部未残留任何瘢痕。结论改良经颅径路行前颅底肿瘤切除并双重组织瓣重建颅底的手术方法能使肿瘤获得良好的暴露,便于术中切除肿瘤的同时完成颅底重建,并获得良好效果。     

A 5-year review of 71 consecutive anterior skull base tumours.

Techniques used in craniofacial surgery have found extensive application in the management of skull base tumours. The improved exposure gained via osteotomies for facial disassembly has facilitated the en-bloc resection of tumours with clear surgical margins, and the advent of vascularised seals has significantly reduced the risk of meningeal contamination. We present our experience with the extirpation and reconstruction of 71 benign and malignant tumours of the anterior skull base over a 5-year period. Survival and functional outcome data are presented, with an emphasis on the wide range of pathologies and primary treatment strategies seen at presentation. Criteria used in flap selection and the role of prosthetics are discussed. Observations are offered on salvage surgery, demonstrating that excellent palliation can be achieved, even in cases with massive recurrent disease.     

Case of frontal sinus carcinoma for which anterior skull base surgery was performed: application for resection of orbita

Carcinoma of the nasal cavity and paranasal sinuses occupies only 3% of head and neck malignant tumors in the West, but 10% in Japan. Frontal sinus carcinoma is much rarer, occupying less than 1% of carcinoma of the nasal cavity and paranasal sinuses. In Japan, only 38 cases have been reported for 40 years, from 1924 to 1964. Almost all patients died within one year because only facial resection was performed. We report a case of frontal sinus carcinoma (squamous cell carcinoma) invasive the to skull base for which we performed anterior skull base surgery and can confirm two years survival in our institution. In this case, resection of the right orbit contents was performed, but careful consideration must be given to resection and repair of orbit contents for maintaining a patient's quality of life. Not only computed tomography scan and magnetic resonance imaging but also angiography is thought to be useful, especially for the ophthalmic artery (in this case, the lacrimal artery) is important.     

Successful treatment of large malignant tumor involving the skull base by radiosurgery combined with intraarterial chemotherapy and embolization.

Stereotactic radiosurgery can be used to treat malignant tumors involving the skull base. While it avoids extensive sacrifice of the normal structures surrounding the tumor, radiosurgery does not eradicate the tumor mass immediately. We present a patient with a large hypervascular malignant tumor involving the skull base that resulted in intracranial hypertension. He was successfully treated with stereotactic radiosurgery combined with intra-arterial chemotherapy and embolization of the arteries feeding the tumor. We discuss radiosurgery, chemotherapy, embolization and other therapeutic modalities for treating large malignant tumors involving the skull base.     

In situ hybridization of prostate-specific antigen mRNA in human prostate.

Prostate-specific antigen (PSA) mRNA was detected by in situ hybridization utilizing a 428 base pair [35S]-labelled cDNA probe from the 3' noncoding region of the PSA gene. Thirty six fresh surgical specimens were collected from patients undergoing radical retropubic prostatectomy for carcinoma of the prostate. Quantitative analysis of the levels of PSA mRNA in both the benign and malignant tissues was performed using an IBAS 2000 Image Analysis System. The results of this study demonstrated that there is a significant decrease in the expression of PSA mRNA in the carcinoma tissue when compared to the benign epithelium. The average binding (number of silver grains/1 x 10(4) microns. 2) for 20 specimens of malignant epithelium was 475 +/- 161 and 586 +/- 140 for 16 specimens of benign epithelium (p less than 0.05). Eleven patients had both benign and malignant tissue from the same surgical specimen available for study. From these paired specimens, the PSA mRNA expression was also significantly reduced in the malignant epithelium when compared to the benign epithelium, 445 +/- 162 and 588 +/- 135 respectively (p less than 0.005). The PSA protein was detected using a monoclonal antibody to PSA with an immunohistochemical staining technique. The PSA protein expression paralleled the expression of the PSA mRNA in the majority of the tissue sections. Many of the tumor specimens showed a heterogeneous expression of PSA, whereas all of the benign epithelium had a uniform high level of PSA expression. In conclusion, PSA mRNA and protein are located only within the glandular epithelial tissue, the expression of PSA protein parallels that of the PSA mRNA, and both the PSA protein and PSA mRNA are significantly decreased in the malignant epithelium when compared to benign prostatic epithelium.