BRAF-mutated pleomorphic xanthoastrocytoma is associated with temporal location, reticulin fiber deposition and CD34 expression.

BRAF V600E mutation and homozygous deletion of CDKN2A (p16) are frequent molecular alterations in pleomorphic xanthoastrocytomas (PXAs). We investigated 49 PXAs for clinical, histological and immunohistochemical characteristics related to BRAF mutation status. BRAF mutation was detected by immunohistochemical assay and DNA sequencing in 38/49 (78%) tumors. All but one PXA located in the temporal lobe harbored a BRAF V600E mutation (23/24; 96%) compared with 10/19 nontemporal PXAs (53%; P = 0.0009). Histological and immunohistochemical analysis demonstrated increased reticulin deposition (76% vs. 27%; P = 0.003) and a more frequent expression of CD34 in BRAF-mutant PXAs (76% vs. 27%; P = 0.003). We further investigated the utility of combined BRAF V600E (VE1) and p16 analysis by immunohistochemistry to distinguish PXAs from relevant histological mimics like giant-cell glioblastoma. Among PXAs, 38/49 (78%) were VE1-positive, and 30/49 (61%) had a loss of p16 expression. The combined features (VE1 positivity/p16 loss) were observed in 25/49 PXAs (51%) but were not observed in giant-cell glioblastoma (VE1 0/28, p16 loss 14/28). We demonstrate that temporal location, reticulin deposition and CD34 expression are associated with BRAF mutation in PXA. Combined VE1 positivity and p16 loss represents a frequent immunoprofile of PXA and may therefore constitute an additional diagnostic tool for its differential diagnosis.

Small supratentorial, extraaxial primitive neuroectodermal tumor causing large intracerebral hematoma.

A 16-year-old boy presented with an unusual case of a supratentorial, extraaxial small round blue cell tumor of the central nervous system, which was most likely a primitive neuroectodermal tumor (PNET). Preoperative computed tomography and magnetic resonance imaging showed a large multistage hematoma in the left central region. Intraoperatively, a small, superficial tumorous lesion was found between the sagittal sinus and a large cortical vein hidden by the hematoma. The histological diagnosis was PNET. This tumor is one of the most aggressive intracerebral tumors, not only in children, so treatment strategies must be early, profound, and interdisciplinary. This case represents an important example of atypical extraaxial appearance of this lesion, which should be considered in the differential diagnosis of cortical or subcortical hemorrhage, since complete resection of this lesion is critical for the successful treatment and outcome.

Transsphenoidal extension of heterotopic glioneuronal tissue: pathoanatomic considerations in symptomatic neonates.

PURPOSE: In this clinical investigation, we aimed (1) to re-evaluate the nature of glioneuronal tissue with transsphenoidal extension and how it fits into the nomenclature of midline malformations and mass lesions; (2) to find out if our imaging findings support current pathoanatomic concepts of clefts and canals in the sphenoid body of newborns. METHODS: In two neonates with respiratory distress due to nasopharyngeal masses, 3T MRI was performed, and CT in one of them. Imaging features were analyzed in consensus by two pediatric neuroradiologists with histological reports being available. An interdisciplinary panel compared the findings to those of case publications and differential entities from our institutional case collection. RESULTS: Referring to our rare case of transsphenoidal cerebral heterotopia and unique case of hypothalamic hamartoma with transsphenoidal herniation, glioneuronal heterotopia may definitely extend through the sphenoid bone. Consequently, there is reason for brain heterotopias to be labeled as such also in case of an intracranial component. Connection between heterotopic glioneuronal tissue in the nasopharynx and a hypothalamic hamartoma may go along with indistinct margins to normal brain. Neither extension through a transsphenoidal cleft nor association with a cleft palate are specific for cerebral heterotopia. Our findings support the hypothesis that transsphenoidal cerebral heterotopias do not or at least not invariably follow the route of Rathke's pouch, known as the craniopharyngeal canal. CONCLUSION: Transsphenoidal glioneuronal heterotopia should be the top differential diagnosis in MR imaging if a non-enhancing nasopharyngeal mass of an infant extends through a craniopharyngeal cleft within the intersphenoid synchondrosis.

Multiple intracranial melanoma metastases: case report and review of the literature.

Although intracerebral metastases of malignant melanoma are common, those located in the sellar region and within the pontocerebellar area are extremely rare. Furthermore, to our knowledge, there is no report about melanoma metastasis to the epiphysis published so far. We report here a 46-year-old patient who had metastatic lesions in the sellar region, cerebellopontine area and epiphysial gland, preceded by a primary melanoma at her left shoulder. The diagnosis of sellar metastasis was confirmed histopathologically following a stereotactic biopsy. The patient received whole-brain irradiation therapy combined with chemotherapy. After 10 months, she died from a severe hemorrhage in the cerebellopontine angle. Autopsy findings confirmed melanoma metastases both in the cerebellopontine angle and additionally in the epiphysial gland. To our knowledge, this is the first case of multiple intracranial melanoma metastases including the suprasellar region, the pontocerebellar and epiphysial area.