Contributed by Thomas S Jacques, Alan Valentine†, Robert Bradford‡, James E McLaughlin
Departments of Histopathology, Neuroradiology† and Neurosurgery‡
The Royal Free Hospital, London
A woman in her 70s presented with a lumbosacral plexopathy secondary to hip surgery. During her initial investigations, a CT head scan had been requested and this had demonstrated an asymptomatic incidental meningeal tumour in the left occipital region. MRI (Fig 1A, T1-weighted MRI after gadolinium enhancement) showed an enhancing mass consistent with a benign meningioma and the patient was managed conservatively.
She presented 6 months later, with a 6-week history of headache, dizziness and right homonymous hemianopia. CT scans showed enlargement of the tumour. At craniotomy, a vascular tumour was found in the left parieto-occipital region adherent to the sagittal sinus. It was excised completely.
She was well for the next 14 months and then presented with a 2-week history of confusion and a mild right hemiparesis. A CT scan demonstrated recurrent tumour with substantial mass effect at the site of her previous tumour. MRI showed a large heterogenous enhancing lesion with a cystic or necrotic component (Fig 1B -T1-weighted; Figure 1C -T1-weighted with gadolinium enhancement, Figure 1D -T2-weighted). At craniotomy, there was a parieto-occipital tumour with no clear line of dissection between the tumour and cortex. The tumour was debulked but a remnant of tumour was left adherent to the sagittal sinus. Following surgery, her hemiparesis improved partially and she refused further treatment.
She was readmitted 6 months later with worsening confusion. A further CT scan demonstrated substantial intracranial progression of the mass as well as a large extracranial component. She was managed conservatively.
Sections from the original tumour showed interlacing fascicles of spindle-shaped cells (Figs 2A and B). Areas were present where nest of cells formed into whorls but there were infrequent psammoma bodies. In places, there were prominent areas of confluent necrosis and small areas of high cellularity. Mitoses appeared relatively frequently but little cytological atypia was seen. Invasion of the brain was not seen and a diagnosis of atypical meningioma was made.
The recurrent tumour consisted of a similar arrangement of spindle cells with similar cytological features to the original tumour cells (Fig 2C). However, areas of whorl formation and psammoma bodies were not prominent. In addition, there were many areas of strap-like cells with prominent eosinophilic cytoplasm and cytoplasmic striations (Fig 2D - see arrow and inset for an eosinophilic striated cell). The recurrent tumour had a high mitotic rate and areas of confluent necrosis. It was invading the adjacent brain.
The strap cells were strongly positive for desmin (Fig 2E) and MyoD with only weak and focal staining for smooth muscle actin. Desmin staining highlighted the cross striations (Fig 2E -arrow).
Electron microscopy demonstrated cytoplasmic striated parallel filaments within the strap cells (Fig 2F).