Choristoma of the optic nerve and chiasm

Optic Nerve Choristoma Mimicking a Neurenteric Cyst

Optic nerve choristomas are rare entities in which a developmental focus of histologically normal tissue is abnormally located within or along a segment of the optic nerve. Although benign, choristomas may demonstrate slow growth, ultimately resulting in visual field deficits due to compression of the adjacent nerve in the few cases reported in the anterior fossa. Choristomas may have cystic components, though this has not been described in such lesions along the optic nerve. Here, a predominantly cystic optic nerve choristoma is described, with radiologic features mimicking those of an anterior cranial fossa neurenteric cyst. The case highlights the radiology-pathology correlates of choristomas and reviews the surgical approach and management of patients with such lesions.

Clinico-radiological Diagnosis of Optic Nerve Choristomas

Optic nerve choristomas are very rare lesions. They are characterised by the presence of fat cells, mesodermal collection of fibrous tissue and smooth muscle, and atrophic optic nerve tissue. Although the condition can be diagnosed on histology, it is not always possible to carry out surgical exploration for tissue diagnosis in view of the apical location of the lesion and the inherent risk to vision from surgery. Detailed neuro-imaging becomes vital in these cases for diagnosis. We report a case of a patient with an optic nerve choristoma diagnosed on neuroimaging, review the current literature related to this condition, and discuss the key clinico-radiological features of optic nerve choristomas.

Neuromuscular choristoma: characteristic magnetic resonance imaging findings and association with post-biopsy fibromatosis

OBJECTIVE

To describe imaging characteristics of neuromuscular choristomas (NMC) and to differentiate them from fibrolipomatous hamartomas (FLH).

MATERIALS AND METHODS

Clinical and imaging characteristics of six patients with biopsy-proven NMC and six patients with FLH were reviewed by musculoskeletal, a pediatric, and two in-training radiologists with a literature review to define typical magnetic resonance imaging features by consensus. Five radiology trainees blinded to cases and naive to the diagnosis of NMC and a musculoskeletal-trained radiologist rated each lesion as having more than or less than 50% intralesional fat, as well as an overall impression using axial T1 images. Sensitivity, specificity, accuracy, and interobserver agreement kappa were determined.

RESULTS

Typical features of NMC include smoothly tapering, fusiform enlargement of the sciatic nerve or brachial plexus elements with T1 and T2 signal characteristics closely following those of muscle. Longitudinal bands of intervening low T1 and T2 signal were often present and likely corresponded to fibrous tissue by pathology. Four of five patients with long-term follow-up (80%) developed aggressive fibromatosis after percutaneous or surgical biopsy. Nerve fascicle thickening often resulted in a "coaxial cable" appearance similar to classic FLH, however, using a cutoff of <50% intralesional fat allowed for differentiation with 100% sensitivity by all reviewers and 100% specificity when all imaging features were utilized for impressions. Agreement was excellent with all differentiating methods (kappa 0.861-1.0).

CONCLUSIONS

NMC can be confidently differentiated from FLH and malignancies using characteristic imaging and clinical features. When a diagnosis is made, biopsy should be avoided given frequent complication by aggressive fibromatosis.

Fibromatosis: a potential sequela of neuromuscular choristoma

OBJECT

Neuromuscular choristoma (NMC) is a rare peripheral nerve lesion in which mature skeletal muscle fibers lie within the nerve and its fascicles. Given limited follow-up, its natural history is poorly understood. The occurrence of aggressive fibromatosis in one of the authors' patients and its occurrence in reported cases suggests an etiological relationship between the 2 lesions. This study attempts to explain the association and its frequency.

METHODS

All cases of NMCs seen in consultation or treated at the Mayo Clinic were identified. Demographic and clinical data were reviewed in cases with coexistent aggressive fibromatosis. Pathology and neuroimaging studies were reexamined. In addition, an extensive literature review was performed to explore the association of NMC with aggressive fibromatosis, with special attention given to pathological and imaging characteristics and the development of aggressive fibromatosis.

RESULTS

The authors identified 10 patients with a diagnosis of NMC who were treated at the Mayo Clinic between 1992 and 2010. Four of 5 with adequate follow-up had developed a definite or suspected aggressive fibromatosis. A review of the initial pathological specimens in these cases revealed no evidence of fibromatosis, but all of the lesions exhibited accompanying hypocellular collagenous tissue. On MR images, all cases showed areas of low signal intensity, which significantly differed from muscle, nerve, and NMC components. On available serial MR imaging studies, aggressive fibromatosis seemed to originate in such lower-intensity regions. In the 18 previously reported cases of NMC, 5 patients developed recurrent masses diagnosed as either definite (2 cases) or possible (3 cases) fibromatosis. Review of the published imaging studies in these cases suggests the presence of lower intensity areas similar to those observed in the 10 patients treated at the Mayo Clinic.

CONCLUSIONS

This study confirms that the development of aggressive fibromatosis in patients with NMC has been underreported. A direct relationship between the NMC and the development of aggressive fibromatosis is suggested by pathological and neuroimaging evidence.

The optic nerve: radiologic, clinical, and pathologic evaluation

The radiologic investigation of the optic nerve plays an integral part in the diagnostic evaluation of diverse lesions of the optic pathways including inflammatory diseases, vascular disorders and benign and malignant tumors and these radiologic modalities consist principally of CT and MR imaging and, in vascular lesions, MR angiography and conventional angiography. The selection of radiologic studies and their focus is based on the ophthalmologic examination where the ophthalmologist can often determine the suspected location of lesions in the anterior or posterior visual pathways. Furthermore, inspection of the eye, including adnexal structures and funduscopy, provides additional information in the clinical assessment of these patients. With technical advances in the last few years, CT and MR imaging can detect lesions and determine their location and extent with high sensitivity and specificity. This article discusses the radiologic, clinical, and pathologic evaluation of the optic nerve.

Choristoma of the optic nerve: case report

OBJECTIVE AND IMPORTANCE

Optic nerve choristoma is a rare lesion composed of adipose tissue and smooth muscle involving the optic nerve. Few cases have been reported.

CLINICAL PRESENTATION

A 20-year-old woman presented with a history of slowly progressive visual loss in the left eye. On T1-weighted magnetic resonance imaging studies, after frequency-selective fat saturation, an optic nerve mass was detected at the level of the optic canal with signal characteristics suggesting the diagnosis of optic nerve lipoma.

INTERVENTION

At left frontotemporal craniotomy, the intracranial optic nerve appeared thin and atrophic proximally and was covered by abundant adipose tissue distally. Because no cleavage plane could be identified between the fatty lesion and the optic nerve, which appeared splayed within the adipose tissue, the nerve was resected after an intraoperative biopsy. The presence of two heterotopic mesodermal elements, a rim of adipose tissue admixed with bundles of mature smooth muscle, extending into the nerve septa, warranted a diagnosis of optic nerve choristoma.

CONCLUSION

Optic nerve choristoma is an uncommon optic nerve lesion. Even if imaging studies are highly suggestive of the diagnosis, pathological confirmation is required because of the high adipose tissue content in the majority of cases. The lesion, most likely malformative and nonneoplastic in nature, can be the cause of progressive visual loss.

Choristoma of the intracranial maxillary nerve in a child. Case report

This report describes what the authors believe to be the first reported case of choristoma of the intracranial maxillary nerve. This 12-year-old girl presented with a 5-year history of severe isolated left-sided trigeminal neuralgia. Computerized tomography and magnetic resonance imaging revealed a mass below the anterior portion of the left cavernous sinus, enlarging the foramen rotundum. Total resection was achieved via a pterional extradural approach. Histological examination revealed a choristoma composed of smooth-muscle fibers. The histogenesis of these tumors when they develop in a nerve remains unclear. They may represent abnormal migration or proliferation of neuroectodermal tissue in or close to a peripheral nerve. Total removal of these tumors should be attempted at initial diagnosis.