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65-Year-Old with Concern for Compressive Optic Neuropathy
This case features a 65-year-old presenting with concern for compressive optic neuropathy, ultimately diagnosed with fibrous dysplasia of the skull base.
Imaging overview:
Coronal and axial non-contrast CT demonstrates homogeneous expansion of the diploic space with a ground glass appearance and intact cortex involving the skull base, narrowing the optic canal and producing mass effect on the optic nerve. The imaging appearance is classic for the craniofacial subtype of fibrous dysplasia, which commonly involves the anterior skull base and calvarium.
Clinical insight:
Fibrous dysplasia is a benign fibro-osseous lesion in which normal bone is replaced by fibrous tissue and immature woven bone. The classic CT appearance is homogeneous ground glass expansion of the diploic space with an intact cortex. Mixed lucent and sclerotic regions, sometimes termed “pagetoid,” may also be seen. The craniofacial subtype has a predilection for the anterior skull base and calvarium, and can narrow neurovascular foramina, leading to compressive cranial neuropathies such as optic neuropathy or hearing loss. MR appearance is variable and less specific than CT, making CT the preferred modality for diagnosis and surgical planning.
Case courtesy of Jessica Houk, MD, Duke University Medical Center.