Contributed by Aurélie Beaufrère1, Mathilde Fouet2, Onorina Bruno3, Dominique Cazals-Hatem1, Stéphane Goutagny2
1Department of Pathology, 2Department of Neurosurgery, 3Department of Radiology, Assistance Publique Hôpitaux de Paris, Hôpital Beaujon, Clichy, France.
A 19-year-old male was referred for a blurred vision and eyestrain associated with occipital headache for several weeks. Ophthalmologic examination showed left homonymous hemianopia and papilledema on fundoscopy. The CT scan showed a 7 cm diameter lobulated hyperdense mass with calcifications. On MRI, the lesion was hyperintense on T2 and hypointense on T1 weighted images with moderate gadolinium enhancement. The lesion was well demarcated and laid on tentorium. Diffusion weighted imaging did not exhibit restriction (High apparent diffusion coefficient (ADC)). Surrounding brain parenchyma was normal (Figure 1). The lesion was hypoperfused when compared to normal brain (Figure 2). MRI spectroscopy (Figure 3) showed a high choline to creatine ratio (suggesting high cell membrane turn over) and elevated lipids and NAA. The lesion was totally removed via a right parietal craniotomy. Intraoperatively, the lesion was readily visible at the surface of the brain, firm, with a clear dissection plan. It was inserted on the falx cerebri and the tentorium. Gross examination showed a firm lobulated white lesion (Figure 4). There was no evidence of hemorrhage or necrosis.
Histopathology showed a tumor composed of lobulated sheets of mature hyaline cartilage (Figure 5). Focal endochondral ossifications were seen (Figure 6). The cellular density was heterogeneous. Some binucleations were present. No atypia or mitosis was seen (Figure 7). Proliferation index (Ki67) was less than 2%. The lobulated sheets of mature hyaline cartilage embedded in a loose highly vascularized connective tissue. A pseudo fibrous capsule covered the tumor. No brain tissue was visible. What is your diagnosis?