CASE 35
By: Dr. Waleed Althobaity, MD
HISTORY: 26-year-old complaining of right hip pain.
What are your findings?
What are the differential diagnosis?
What is the most likely diagnosis?
FINDINGS:
AP (A) and lateral oblique (B) plain radiographs of right hip demonstrate femoral neck and intertrochanteric lytic lesion with ground glass matrix. Peripheral rim of sclerosis is seen (Rind sign). There is incomplete pathological fracture at the medial femoral neck. No aggressive features are seen.
Coronal CT scan of right hip (C) again showed the ground glass appearance and the thick peripheral sclerosis of the femoral lesion.
DIFFERENTIAL DIAGNOSIS:
Fibrous dysplasia.
Interosseous lipoma.
Liposclerosing myxofibrous tumor (LSMFT).
DIAGNOSIS:
Fibrous Dysplasia with pathological fracture.
PEARLS AND DISCUSSION:
Fibrous dysplasia is a condition in which there is replacement of normal bone by abnormal fibro-osseous tissue with rapid bone turnover. Mono static fibrous dysplasia most commonly affecting the femur (with a predilection for the femoral neck), the tibia, the rib (representing the most common benign lesion of the rib) and the base of skull. Because these lesions are asymptomatic, most of them are discovered incidentally on radiographs obtained for other cause. The most common complication is pathological fracture which may be the first presentation like in this case. Solitary fibrous dysplasia may be surrounded by a characteristic thick band of reactive bone creating a rind sign.
Keep in your mind these three differential diagnoses for the lytic lesion at femoral inter-trochantric location. Look for rind sign and ground glass opacity for FD. Look for intra-lesion calcification (by CT and X-ray) and fat signal intensity in MRI to support diagnosis of intra-osseous lipoma. The LSMFT radiographically may look identical to focus of fibrous dysplasia but usually, there are mixed MRI signal intensity reflected histological components of this entity which includes fibroxanthoma, myxomatous and fat necrosis. Although, there is a clinical debate regarding the LSMFT, but still it’s a good differential diagnosis for inter-trochantric femoral lesion.
FURTHER READINGS
Greenspan, Adam; Borys, Dariusz (2015-09-21). Radiology and Pathology Correlation of Bone Tumors: A Quick Reference and Review (Kindle Locations 5142-5143). LWW.
