Chondroma of the falx cerebri: A case report and review of literature

Intracranial extra-axial chondromas: clues to computed tomography and magnetic resonance imaging diagnosis

AIM

We aimed to describe the computed tomography (CT) and magnetic resonance (MR) imaging findings of intracranial extra-axial chondroma.

MATERIAL AND METHODS

We retrospectively evaluated the imaging findings of CT and MR examinations of six patients (three men and three women, aged 21-66 years) with histopathological diagnoses of intracranial extra-axial chondroma.

RESULTS

Four tumors were located in the frontal region and two in the cavernous sinus. All the tumors showed low signals on diffusion-weighted images and high signals on apparent diffusion coefficient maps without restricted diffusion. There was no perifocal edema in all the tumors. Cavernous sinus chondromas were associated with bone erosion and anterior displacement of the internal carotid arteries, but without calcification. Calcification was present in all frontal chondromas. All the tumors revealed low signals on T1-weighted MR images. Frontal chondromas revealed mixed signals, but cavernous sinus chondromas were brightly hyperintense on T2-weighted MR images. No enhancement was detected in the two chondromas. An intense homogeneous enhancement was detected in a cavernous sinus chondroma.

CONCLUSION

The imaging appearances of frontal extra-axial chondromas and cavernous sinus chondromas may have different imaging appearances. Although there is a wide range of imaging findings, the absence of restricted diffusion, perifocal edema, enhancement, and presence of low signals on T1-weighted MR images in a well-circumscribed calcified extra-axial mass should suggest an intracranial chondroma.

Diagnostics of IDH1/2 Mutations in Intracranial Chondroid Tumors: Comparison of Molecular Genetic Methods and Immunohistochemistry

Intracranial chondroid tumors are a heterogeneous group of neoplasms characterized by the presence of a cartilage matrix. These tumors exhibit overlapping clinical and histological features. Mutations in IDH1/2 genes serve as important diagnostic markers of tumor type, particularly chondrosarcoma. To improve the accuracy of IDH1/2 diagnostics, we compared three methods: biochip assay, real-time PCR with DNA melting analysis using TaqMan probes and sequencing (qPCR-DMA-Sanger), and immunohistochemistry (IHC). Tumor samples from 96 patients were investigated. The IDH1 mutations were detected in 34/64 (53%) chondrosarcomas; IHC detected 27/56 (48.2%) mutations, the qPCR-DMA-Sanger method 27/59 (46%) mutations, and the biochip assay revealed 29/60 (48.3%) mutations. The detection of IDH1 mutations in chordoma (2/15) and osteosarcoma (2/7) suggested the need for a revised diagnosis. In benign tumors, IDH1 mutations were present in chondroma (4/6), but absent in chondromyxoid fibroma (0/4). The most frequent IDH1 mutations were R132C (60%), R132L, and R132G (13.5% each), R132H (8%), and R132S (5%). The concordance between the biochip assay and IHC was 90%, between IHC and PCR-DMA-Sanger 83%, and between biochip assay and qPCR-DMA-Sanger was 98%, respectively. No IDH2 mutations were found. The use of independent diagnostic methods may improve the detection of IDH-mutant specimens in chondroid tumors.

Falcine chondroma: illustrative case

BACKGROUND

Chondromas are benign cartilaginous tumors that are rarely seen in the brain.

OBSERVATIONS

A 58-year-old woman had undergone routine brain imaging after a motor vehicle accident and was incidentally found to have a right falcine lesion. Contrast magnetic resonance imaging showed a mostly nonenhancing mass with discontinuous rim enhancement. She was taken to the operating room and pathology revealed a chondroma.

LESSONS

Falcine intracranial chondromas are rare and typically misdiagnosed as meningiomas. Chondromas should be in the differential for patients presenting with nonenhancing falcine lesions.