Fat in the brain: Facts and features.

The presence of fat within a lesion in the brain is not only easy to identify on both CT/MRI but also can help narrow the differential. The purpose of this paper is to illustrate the spectrum of common and rare fat-containing lesions in the brain that are encountered in clinical practice. This paper intends to discuss 15 such lesions which are confirmed by MRI findings and histopathological correlation. We divided the spectrum of fat-containing lesions into lesions with adipose cells, lesions with cholesterol-rich content and tumours with lipomatous differentiation/transformation. Knowledge of these common and rare fat-containing lesions is essential for making the right diagnosis or narrowing the differential diagnosis.

CNS paraganglioma: 15-year experience in a tertiary care hospital with literature review.

Paraganglioma that involves the CNS may mimic clinico-radiologically many other commoner entities. The current study presents a wide view of the clinical, radiological, and histomorphological spectrum along with rare associations that can occur concurrently with this lesion. The most common site of infliction in CNS is the spine and, in the current series, involvement of the lumbar spine was most frequent. Both clinical and radiological features point towards other more common differentials, including neurofibroma/schwannoma and ependymoma. Some studies suggest rich vascularity (cap sign) and salt pepper appearance in T2-weighted images to serve as soft pointers towards diagnosing it on magnetic resonance imaging, however, in our series we did not encounter the same.

Fatal holocord recurrence of a pregnancy-related, low-grade spinal ependymoma: case report and review of an unusual clinical phenomenon.

INTRODUCTION: Pregnancy-related spinal tumors (PRSTs) are unusual tumors that present during pregnancy or within a year after delivery. We describe a fatal holocord recurrence of a spinal ependymoma, which, to the best of our knowledge, is one of the most extensive PRSTs reported thus far. CASE PRESENTATION: A 21-year-old primigravida presented at 6 months of gestation with urinary incontinence for 2 months and spastic paraparesis for 1 month. MRI showed a conus intramedullary lesion from T10 to 12. Near-total resection of the lesion was performed. The histopathological diagnosis was that of a cellular ependymoma (WHO grade II). The patient presented 6 months later with progressive quadriparesis and breathing difficulty. MRI demonstrated holocord recurrence of the tumor with edema extending to the pontomedullary junction. The patient succumbed to respiratory failure before decompression of the tumor could be performed. DISCUSSION: This case highlights an unusual clinical course of a pregnancy-related, low-grade spinal ependymoma. The possible hormonal and genetic mechanisms underlying the aggressive involvement of the entire spinal cord by the recurrent tumor are discussed in the light of a literature review. Future studies may shed light on the possibility of utilizing these mechanisms as therapeutic targets to alter the clinical course of aggressive spinal ependymomas.

Sellar-Suprasellar Paraganglioma: Report of 2 Cases and Review of Literature.

BACKGROUND: Intracranial paragangliomas are infrequent and those occurring in the sellar-suprasellar region are rare, with only 31 cases described in literature. CASE DESCRIPTION: We describe 2 cases of sellar-suprasellar paragangliomas in the light of a literature review. The first patient was a 13-year-old boy who presented with an intensely enhancing lesion in the sellar-suprasellar region with multiple flow voids within. Resection of the lesion was limited to a biopsy in view of its hypervascular nature. A second attempt at resection following partial embolization of the lesion was also unsuccessful. The tumor showed progressive reduction in size following radiotherapy. The second case was a 20-year-old man who presented with a similar tumor in the same location. He also had a probable metastatic deposit in the foramen of Magendie. An attempted surgical resection of the suprasellar lesion was abandoned after a biopsy. The patient improved symptomatically after radiotherapy. CONCLUSIONS: We report 2 cases of paraganglioma occurring in a rare location. Presence of flow voids within tumors in the sellar-suprasellar location should alert the surgeon to this entity. The hypervascular nature of these tumors may limit the extent of resection. In cases of inadequate tumor decompression, or if there is evidence of growth of residual tumor, radiotherapy can help to stabilize the disease.

Malignant Transformation of Pediatric Low-grade Gliomas: Report of Two Cases and Review of a Rare Pathological Phenomenon.

Low-grade gliomas (LGGs) are the commonest benign central nervous system (CNS) tumors seen in children. Unlike LGGs in adults, pediatric LGGs rarely undergo malignant transformation. The incidence of malignant transformation of LGGs in the pediatric population has been reported to be up to 10%. Of these, a few patients have demonstrated this phenomenon even without adjuvant radiation therapy. We report two such unusual cases. A 7-year-old girl presented with a left temporal lesion that was operated upon and was reported as pilocytic astrocytoma (WHO grade I). She presented with a malignant transformation of the tumour 8 years later. The second case was a 10-year-old boy, who had a left frontoparietal ganglioglioma (WHO grade I) that demonstrated malignant transformation to an anaplastic ganglioglioma (WHO grade III) 10 months after the initial surgery. Multiple studies have thrown light on the molecular genetics behind malignant transformation of LGGs in children. These genetic changes can perhaps serve as targets for potential future therapeutic interventions. It is important that patients with LGGs at risk of malignant transformation must be identified early so that a more aggressive treatment strategy can be adopted.

Aggressive Primary Pediatric Intracranial Malignant Melanoma: Sphinx of the Tissue Diagnosis.

It is often intriguing to suspect and confirm the diagnosis of primary malignant melanoma (PMM) in the brain without any evidence of neurocutaneous melanosis. We report a 16-year-old male patient with malignant melanoma which intraoperatively was small sized, soft, fleshy, hemorrhagic in appearance resembling hematoma. Interestingly, the histopathology showed prominent papillary architecture with a differential diagnosis of papillary meningioma and ependymoma and perplexed the tissue diagnosis. This case is discussed in light of very uncommon occurrence of intracranial PMM in pediatric age group, enigmatic histological features, and aggressive nature of lesion with rapid progression despite complete excision following radiation therapy.

Unusual Radiological Presentation of Intracranial Dermoid Cyst: A Case Series.

Intracranial dermoids are rare congenital lesions of the brain that account for < 1% of all intracranial tumors. Even though they are rare, typical computed tomography (CT) scan and magnetic resonance imaging (MRI) features along with location allow radiological diagnosis in the majority of patients. Radiologically, dermoid cysts typically appear as nonenhancing low-density masses on CT scan and are hyperintense on T1-weighted (T1-W) MRI sequences with variable signal on T2-W sequences. We describe two cases of dermoid with unusual imaging appearance with the presence of mural nodule in both the cases. The recognition of atypical radiological features can avoid diagnostic pitfalls and is clinically relevant for overall surgical management.

Rosette-Forming Glioneuronal Tumor in Opticochiasmatic Region-Novel Entity in New Location.

BACKGROUND: Rosette-forming glioneuronal tumour [RGNT] is a relatively rare entity first identified as a separate entity in 2002. We are reporting the second case of RGNT in the opticochiasmatic region. CASE DESCRIPTION: We report a case report and literature review of RGNT with syndromic association. CONCLUSIONS: Although initial reports were predominantly in the fourth ventricle, many recent reports have identified the possibility of its occurrence outside fourth ventricle in pineal gland, spinal cord, septum pellucidum, lateral ventricle, and suprasellar region. To date, only 1 case of RGNT involving the opticochiasmatic region has been reported in a patient with neurofibromatosis type 1. Genetic analysis of this rare tumor identified 3 hotspots involving somatic mutations of FGFR-1 and PIK3CA and a germline mutation involving PTPN11, which can be targets for therapeutic intervention in cases where complete resection is not possible. To the best of our knowledge, we report the first case of RGNT involving the opticochiasmatic region without any syndromic association. Other cases of RGNT with syndromic associations provide us with insight into possible therapeutic interventions.

Myriad of MR imaging phenotypes of primary central nervous system lymphoma in a cohort of immunocompetent Indian patient population.

PCNSL (primary central nervous system lymphoma) is a chemosensitive and radiosensitive tumor, and early diagnosis has a significant impact on management. Unlike many other brain tumors, radical surgical excision of PCNSLs is not indicated because these lesions are highly infiltrative and even partial resection leads to a bad prognosis. The goal of this study is to highlight the unusual radiological presentation of PCNSLs and increase the awareness, familiarity, and global database of our observations that pose a challenge on management.

Preoperative Cytoreduction of Clival Giant Cell Tumor: An Effective Replication of the Systemic Modality in the Skull Base.

BACKGROUND: Giant cell tumors (GCTs) are benign tumors with a predilection for the epimetaphyseal region of the long bones. GCTs involving the skull base are rare, and only a few available cases have been reported. Surgical gross total resection is the recommended method of treatment for GCTs. In the case of skull base tumors, it is very difficult to achieve such a result by direct surgical resection alone without any morbidities. Denosumab is a fully humanized monoclonal anti-receptor activator of nuclear factor-κB ligand antibody that has been recently approved by the Food and Drug Administration for the treatment of GCTs that are surgically unresectable, metastatic, and have a high risk of progression and recurrence. Denosumab has been used in many cases involving the long bones. However, in cases of skull base GCTs, only a limited number of cases have been reported. In addition, in such cases, it was used as postoperative chemotherapy owing to subtotal resection. CASE DESCRIPTION: For the present patient, we adopted a unique approach in which denosumab was administered as neoadjuvant chemotherapy to reduce the size of the tumor to a resectable level. Subsequently, surgical resection was performed with good functional and histopathological outcomes. CONCLUSIONS: Our findings emphasize the use of denosumab as a neoadjuvant treatment routinely for all cases of skull base GCTs to achieve safe and complete excision of the tumor.

Clinicopathological and imaging features of lipoastrocytoma: Case report.

Lipidized tumors of the central nervous system are very uncommon, with only a few cases described. We report a case of a 25-year-old woman with a tumor involving the left premotor area. She underwent gross total excision. Histologically, the tumor was composed of glial fibrillary acidic protein-positive glial cells with areas of lipidization. A diagnosis of lipoastrocytoma was rendered. At three-year follow-up she was doing well, supporting the presumed favorable prognosis of these uncommon tumors. Absence of xanthochromic appearance, mitotic activity, necrosis and poor reticulin activity are the differentiating features from the pleomorphic xanthoastrocytoma. We highlighted that these tumors involve the adult and pediatric population and distribute in both supratentorial and infratentorial compartments as well as in the spinal cord.

Tree-in-bud Appearance in the Brain: Fungal Granuloma on Contrast Magnetic Resonance Imaging.

We describe a case of dural-based homogenously enhancing fungal granuloma in a 29-year-old male who presented with 3 months history of headache. The peculiarity of the case was that there were streaky areas of enhancement around the lesion in the brain parenchyma which resembled tree-in-bud like appearance. The patient underwent surgery and histopathological analysis revealed numerous Aspergillus hyphae. To the best of our knowledge, this is the first case report of a fungal granuloma with atypical parenchymal enhancement pattern.

Cervical En-Plaque Extradural Meningioma Involving Brachial Plexus.

BACKGROUND: Meningioma is one of the commonest spinal tumors, with a predilection for intradural occurrence. Its occurrence as an extradural, en plaque variety with extension into the brachial plexus is unusual. CASE DESCRIPTION: A 50-year-old male patient presented with progressive spastic quadriparesis. Magnetic resonance imaging showed an en plaque, epidural soft tissue tumor at C5-C7 levels on the right side with extraforaminal extension into the paraspinal region and the brachial plexus laterally. The patient underwent a C5-7 laminectomy and partial excision of the tumor. Histopathology was reported as psammomatous meningioma (World Health Organization grade I). CONCLUSIONS: An extradural spinal meningioma should be considered in the differential diagnosis of an exclusively extradural spinal tumor. Its occurrence as an en plaque variety is uncommon. We report an unusual case of the en plaque form of extradural cervical meningioma with diffuse involvement of the brachial plexus.

Pituitary apoplexy presenting as a peripheral rim enhancing parasellar mass lesion with dural enhancement along the tentorium.

Pituitary apoplexy is a potentially life-threatening clinical condition caused by rapid enlargement of a pituitary adenoma because of haemorrhage or infarction. The clinical features are typically acute in onset. We report an interesting case of 25-year-old man with complaints of sudden onset of headache and ophthalmoplegia in the right eye one month previously. He had ptosis and complete ophthalmoplegia in the right eye with visual acuity 6/24 and 6/12. Imaging showed a peripheral rim-enhancing mass lesion in the right parasellar and cavernous sinus with a dural tail. He underwent craniotomy and subtotal excision of the lesion. Histopathology was reported as pituitary apoplexy. Hormonal analysis was within normal limits. At two years of follow-up he had complete resolution of ophthalmoplegia and improvement in his vision. It is very uncommon to see pituitary apoplexy evolved in right parasellar region presenting as peripheral rim-enhancing mass lesion.

Giant multi-compartmental suprasellar Rathke's cleft cyst with restriction on diffusion weighted images.

Rathke's cleft cysts are congenital lesions seen in sellar-suprasellar regions. We report a case of giant Rathke cyst in a 43-year-old patient with multi-compartmental involvement who presented with seizures with almost normal visual acuity. We discuss radiological and pathological features of various differential diagnoses for the giant suprasellar Rathke's cyst.

Ampullary carcinosarcoma with osteosarcomatous, small cell neuroendocrine carcinoma and conventional adenocarcinoma components; First report.

Caracinosarcomas are tumours with diverse epithelial and mesenchymal differentiation. They most commonly occur in the female reproductive organs and upper aero digestive tract. They are relatively rare in the gastrointestinal tract and affect the oesophagus most commonly. Ampullary carcinosarcomas are exceptionally rare. We report a case of ampullary carcinosarcoma in a 67-year-old male, with osteosarcomatous, small cell carcinoma and conventional adenocarcinoma components. To the best of our knowledge, this is the first reported case of its kind.