Potpourri of Rare Central Nervous System Tumors
Five interesting and rare central nervous system tumors are presented. These include, Pleomorphic Xanthoastrocytoma with Anaplastic features, Rhabdoid Meningioma, Calvarial Meningioma, Eosinophilic Granuloma of Dural origin, Primary Paraganglioma of Craniospinal Axis. These are in the domain of Oncologic Surgical Neuropathology.
Oncologic surgical neuropathology is a dynamic field. The unparalleled complexity of the central nervous system (CNS) is mirrored by the ever-increasing diversity of recognized neoplastic entities that can afflict the organ. In many instances, the emergence of ‘‘new’’ entities are a reflection of our increasing ability to sub divide large categories of tumors into more refined, clinically and biologically meaningful, subtypes for purposes of patient prognosis and/ or treatment stratification.
We herein describe five interesting case reports of CNS tumors
Case 1 : A 55-year-old male presented with weakness and numbness of right upper and lower limbs since 3 months. Patient had difficulty walking as well as difficulty speaking. In addition, the patient complained of headache since nine months. There was a disturbance of vision in both eyes. Sensations were reduced in the lower side of the maxillary and mandibular region and there was difficulty in hearing in the right ear. Pain sensation was reduced on the right side. Tone and bulk were reduced in right upper and lower limbs. Clinical diagnosis of metastatic tumor in the brain was rendered. Patient underwent a computed tomography (CT) scan and possibilities of multicentric glioblastoma multiforme and metastatic deposits in brain were suspected. Patient underwent right frontal craniotomy with excisional biopsy of both lesions in the right cerebral hemispheres. Preoperatively the tumor was firm and moderately vascular. Microscopic examination revealed sheets of pleomorphic astrocytes showing focal fascicular arrangement and numerous tumor giant cells. The tumor cells showed enlarged, hyperchromatic bizarre nuclei with prominent nucleoli and occasional intranuclear inclusions. The cytoplasm of these tumor cells varied from eosinophilic to hyaline to foamy. Abundant Periodic Acid Schiff (PAS) positive granular eosinophilic bodies were seen. Focal perivascular patchy lymphocytic infiltrate was seen. There was dense reticulin staining around single or grouped tumor cells. There were extensive areas of tumor necrosis and moderate number of mitotic figures of 5 to 6/10 high power field (HPF). The tumor cells were immunohistochemically positive for glial fibrillary acidic protein (GFAP), focally (some cells) positive for synaptophysin and negative for vimentin. Ki-67 index was about 5%. Histological diagnosis of “pleomorphic xanthoastrocytoma with anaplastic features (PXA)” was rendered.
Synchronous, multicentric pleomorphic xanthoastrocytoma with anaplastic features as seen in the present case are extremely rare neoplasms[1,2]. 9% to 20% of PXA astrocytoma to undergo malignant transformation and some of them exhibit anaplastic features at the first presentation. The World Health Organization (WHO) recommends the designation “PXA with anaplastic features” to denote PXA featuring high mitotic activity (3-5 mitoses per 10 HPF) with or without accompanying necrosis. The designations “anaplastic PXA” and “PXA grade III or IV” are currently not recommended by WHO.
Case 2 : A 28-year-old male presented with a history of progressive weakness and decreased sensation in both lower limbs. He also complained of weakness and numbness up to the nipple. There was no bladder involvement. On examination, there was Grade I to II weakness in both lower limbs and sensory loss (touch, pain, temperature) below T3 and T4. Magnetic resonance imaging (MRI) revealed an intradural extramedullary tumor at C7-T1 level. Laminectomy C7-T1 was done with complete excision of the intradural, extramedullary, well circumscribed, firm, vascular tumor arising from dura C7-T1 and compressing the cord significantly. On microscopic examination of the resected tumor, most of the tumor cells exhibited typical rhabdoid morphology with large vesicular often eccentrically located nuclei with distinct nucleoli and abundant cytoplasm containing eosinophilic hyaline inclusions. Numerous psammoma bodies were also seen. Classical meningothelial features with focal whorl formation were scarce and seen only in a few foci. Immunohistochemically, these rhabdoid cells showed epithelial membrane antigen (EMA) as well as vimentin positivity. Final diagnosis of “rhabdoid meningioma lacking malignant features”was given.
In 2000, rhabdoid meningiomas were included in the revised WHO classification of tumors of the CNS as a subtype of meningiomas with increased risk of recurrence and more aggressive growth, corresponding to WHO Grade III. Meningiomas with focal rhabdoid differentiation are considered WHO Grade I. Rhabdoid features should constitute over 50% of tumor to classify a meningioma as a “rhabdoid meningioma” (as per WHO grade III classification of tumors).
Case 3 : A 60-year-old female presented with persistent left sided headaches since 6 months. Headaches were a dull ache type, centered over the left parietal region. Radiographs of the skull revealed a well-defined area of osteolysisin the left frontoparietal region. CT scan showed an enplaque enhancing tumor extending over the left frontoparietal convexity. The calvarial bone was thickened all along the length of the tumor. The underlying dura and brain were normal. The patient underwent a left frontoparietal craniotomy. The bone was thick and extensively vascular. The involved calvarium was resected widely. The extradural meningioma was diffuse and carpet like. It was soft and greyish and only moderately vascular. This mass was removed along with the involved markedly thick dura. Microscopic examination revealed sheets and tight whorls of meningothelial cells with round to oval vesicular nuclei, inconspicuous nucleoli and eosinophilic cytoplasm with indistinct cytoplasmic borders. The tumor cells were permeating in between the existing bony trabeculae of calvarial bone. Occasional cells showed intranuclear pseudoinclusions. There was no mitotic activity or any foci of necrosis. There were large number of psammoma bodies. The case was diagnosed as “calvarial meningioma”.
Extracranial meningiomas are rare and account for 1%–2% of all meningiomas. Calvarial meningiomas are more prone to develop malignant changes (11%) as compared with intracranial meningiomas (2%).
Case 4 : An 11-year-old female child presented to the neurosurgery outpatient department with a swelling in the right frontoparietal region. An osteolytic lesion was detected on X-ray in the right frontal area. MRI demonstrated a well-defined enhancing mass measuring 3.5x3x2.5 cms with a wide dural attachment and an expansile lytic lesion in the frontal bone. A chest X-ray and other radiological examinations showed no other osseous or soft tissue lesions. The patient underwent right parietal extended craniotomy. Intraoperatively there was a soft fleshy mass originating from the dura mater in the right parietal region and protruding out of the bony defect. The lesion was completely removed together with a margin of grossly uninvolved dura and bone. The excised mass was sent to us for histopathological examination. Microscopically, there were sheets and clusters of Langerhans’ cells with typically grooved and irregularly contorted nuclei with a thin nuclear membrane, delicate chromatin and inconspicuous nucleoli. The cytoplasm was abundant and lightly eosinophilic. Abundant eosinophils and frequent multinucleated giant cells were also present. The Langerhans cells were immunoreactive for CD-1a. The case was diagnosed as “eosinophilic granuloma of dural origin”.
In current literature review, only a few cases of eosinophilic granuloma originating from dura mater were found. An inflammatory process of the dural membrane with migration of Langerhans’ cells could be the physiopathological basis for the formation of intradural eosinophilic granuloma.
Case 5 : A 42-year-old female presented with pain and burning sensation in the lower back. Pain was moderate and intermittent initially and became continuous in the last 6 months. Pain was radiating to the gluteal region and increased on coughing and on taking a deep breath. There was no history of urinary or bowel problems. On clinical examination, motor and sensory systems were within normal limits. All the reflexes were present. The spine showed no deformity. X-ray of the lumbar spine was also normal. However MRI showed an intradural, extra medullary, well- defined mass at the L4-L5 level. Possibilities of neurofibroma and ependymoma were suggested. Laminectomy of L3- S1 with near total excision of the tumor was conducted and a 3×3 cm multi-
lobular, pinkish, friable mass arising from cauda equine was excised. On microscopic examination, the tumor was partially encapsulated and comprised of nests and broad anastomosing trabeculae of round to polygonal tumor cells, separated by delicate, fibrovascular septa (zellballen pattern). These tumor cells showed moderately abundant eosinophilic cytoplasm, central round to oval nuclei with finely stippled chromatin, occasional nucleoli and intranuclear inclusions. The tumor cells were positive for chromogranin and synaptophysin. A diagnosis of “paraganglioma of caudal equine” was made.
Primary paragangliomas of craniospinal axis are predominantly found in the intradural, extramedullary compartment at the level of the cauda equina. Current WHO classification of CNS tumors classifies paragangliomas as grade I tumors. Complete surgical resection is considered curative and subtotal resection often leads to recurrence. Total excision is often very difficult owing to the tendency of these neoplasms to infiltrate the cauda equina roots. Less than 1% are locally aggressive.
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