Case report
A 36 years old female patient referred to neurosurgery department, Razi hospital of Birjand, Iran, with the chief complaint of aphasia for 2 month duration. Her past medical history was not significant. Her family history was not noticeable. On examination, the patient was afebrile, with normal vital signs. Tongue was in midline. She had full strength in all extremities and had no other neurologic symptoms. Her laboratory tests were unremarkable. Brain CT scan and T1-weighted, T2-weighted and post-contrast MRI Images were made. T1-weighted MRI showed a large mass with mixed isointense to hypointense signals in left frontoparietal lobe; T2- weighted MRI showed isointense to hyperintense signals; post-contrast MRI showed a mass with heterogeneous enhancement in the left frontoparietal lobe. CT scan demonstrating a large mass with isodensity signals (Figure 1). A preoperative diagnosis of astrocytoma was suspected. It was decided that the patient would undergo surgery. Stereotaxic surgery was performed and the tumor was completely removed.
The biopsied tissues were processed to formalin fixed paraffin embedded (FFPE) preparation, hematoxylin and eosin (H&E) and immunohistochemistry (IHC). Immunohistochemical analysis was performed for CD99 immunomarker. Reverse transcription polymerase chain reaction (RT-PCR) was done to assess gene rearrangement for EWSR1 gene.
The tumor was sent for histopathological examination. On microscopic examination, at lower power, the tumor was undifferentiated and densely cellular. Sheets of small, round to oval, uniform cells with scant clear cytoplasm were seen infiltrating the brain tissue. Some large pleomorphic cells were also evident (Figure 2). Histopathologic findings were suggestive of a malignant small round cell tumor with following differential diagnosis: 1- Ewing sarcoma / primitive neuroectodermal tumor (PNET); 2- neuroblastoma; 3-lymphoma. Immunohistochemical analysis showed diffuse membranous positivity for CD99 but negative staining for LCA. Reverse transcription polymerase chain reaction showed EWSR1 gene rearrangement and confirmed the diagnosis of PNET. Whole-body CT scan was recommended and performed and did not demonstrate any lesion in other parts of her body.
After surgery, the patient’s condition was stable and after two months, the patient’s aphasia gradually resolved. Six months after surgery, follow-up images including MRI of the patient’s brain and whole body scans were performed. There was no evidence of tumor recurrence in these images and no metastatic focus was evident in the images.