Case 15 Skull lesion
Figure 15: MRI and CT of the patient: A coronal with contrast, B axial T2, C sagittal T1, D CT brain.
Clinical presentation
- A 26-year-old male patient with a history of progressive non-pulsatile proptosis associated with diminished vision.
- He has recurrent attacks of left frontal and retroorbital headaches that do not respond to medication.
- Fundus examination reveals no abnormalities.
- Q1: Describe the MRI finding?
- The imaging reveals an anterior skull base lesion eroding the right orbital roof and cribriform plate, with extension into the orbit and nose. It is surrounded by a shell of calcification, featuring mixed internal intensity and heterogeneous enhancement.
- Q2: What is your differential diagnosis?
It includes:
- Fibrous dysplasia
- Fibro-osseous tumors (e.g., ossifying fibroma)
- Primary bone tumors
- Nasopharyngeal tumor
- Skull base meningioma
- Hemangiopericytoma
- Metastasis
- Other less likely diagnoses include lymphoma, osteosarcoma, Paget’s disease, Langerhans cell histiocytosis, infection (osteomyelitis, soft tissue infection, etc.), and aneurysmal bone cyst.
- Q3: How can you differentiate between mechanical diplopia caused by an abnormal mass compressing the eye and neurological diplopia due to oculomotor nerve palsy?
- This can be differentiated by measuring the intraocular pressure while the patient tries to look in the direction of the limited gaze. In cases of neurological diplopia, the intraocular pressure will remain normal.