A Rare Case of Radiculopathy: Monostotic Fibrous Dysplasia of the Sacrum

Could gas-filled pseudocyst mimick extruded disc herniation?

There are case reports and small case series in the literature reporting gas-filled pseudocysts (GFP). However, a systematic review presenting overall view of the disease and its management is still lacking. In the present study, we aimed to make a systematic review of GFP cases, and present an exemplary case of ours. Our second aim was to discuss current theories for pathogenesis of GFP. A systematic review of GFP was conducted using Preferred Reporting Items for Systematic Reviews and Meta-Analyses guideline. Two large-scaled data search engines were used. A total of 53 articles were retrieved from the literature and presented with an exemplary case of ours. Mean age of the historical cohort was 59.47 years. There were 66 male (54.1%) and 56 female (45.9%) patients. The most prevalent clinical presentation was radicular sign/symptom in lower limbs with (29.1%) or without low back pain (LBP) (67%). Gas-filled pseudocyst has most commonly been diagnosed at the lower lumbar spine (L4-L5, 45.3%; L5-S1, 37.7%). Surgery was the treatment of choice in most of the patients (80%). In the whole cohort, 79.1% of the patients had complete recovery. Gas-filled pseudocysts are rarely observed in daily practice. They present mostly in men at the age of 60s. Precise differential diagnosis determination using appropriate imaging would help clinicians treat the patients properly. Gas-filled pseudocysts should be treated similarly to other spinal pathologies causing nerve root compression.

Imaging characteristics of a rare case of monostotic fibrous dysplasia of the sacrum: A case report

BACKGROUND

Fibrous dysplasia (FD) is a common benign intramedullary fibro-osseous lesion. Involvement of the spine is rare, with the literature including only case reports, and cases of monostotic FD (MFD) in the sacrum are extremely rare. A correct preoperative diagnosis of spinal MFD is important for clinicians to select proper treatment.

CASE SUMMARY

We retrospectively assessed a case report of MFD in the sacrum. This patient was examined by computed tomography (CT) and magnetic resonance imaging (MRI), and the diagnosis was confirmed by pathology. A review of the literature was performed to analyze the imaging characteristics and differential diagnoses of spinal MFD. For our patient, the CT scan showed the lesion to be expansile, with ground glass opacity and a sclerotic rim. On MRI, the lesion showed iso-low signal intensity on T1WI and iso-high signal intensity on T2WI. A low signal rim was found on T1WI and T2WI. Our patient was treated by posterior focal excision, decompression, bone grafting, fusion and pedicle screw fixation. A satisfactory result was achieved, with pain disappearance. No complications had occurred at the 1-year follow up.

CONCLUSION

MFD is an expansile osteolytic change. Ground glass opacity and a sclerotic margin are obvious characteristics. The lesion often involves the vertebral body and posterior element. Knowledge of these imaging characteristics of spinal FD could be helpful for diagnosis and prevent unnecessary procedures.