Age / Sex : 20 / M

Age / Sex : 20 / M

Chief complaint :

1) What is your impression?

Two weeks later, you can see the final diagnosis with a brief discussion of this case.

* Send Application Answers to In Sook Lee, MD (lis@pusan.ac.kr)

Courtesy : Kwack, Kyu-Sung, Ajou University Medical Center

Melorheostosis

Discussion

Findings:

On plain radiographs, multiple hyperostostic lesions were seen in the left pelvic bone, para-acetabular region and proximal femur. Especially, cortical hyperostois in the left proximal femur extends along the length of one side of the bone and resembling flowing candle wax.

MR images showed low signal intensities on both T1WI and T2WI in all of the bone lesions. There was no abnormal internal enhancement after contrast administration and no adjacent soft tissue abnormalities.

Differential Diagnosis:

Melorheostosis, Mixed sclerosing bone dystrophy

Diagnosis:  

 Melorheostosis

Discussion:

 Melorheostosis is a rare benign sclerosing bone dysplasia of unknown etiology that localizes in regions of innervation of spinal sensory nerves and correlates with those sclerotomes and myotomes. This disorder tends to be segmental and unilateral and may affect only one bone (monostotic), one limb (monomelic), or multiple bones (polyostotic). The lower extremity is more frequently involved than the upper extremity. Melorheostosis rarely involves the spine, skull, and facial bones. Lesions may occasionally be associated with skin lesions, vascular anomalies, and joint contractures. Histologic findings include variable degrees of cortical thickening consisting of chondroid islands surrounded by mature lamellar and woven bone, as well as adjacent zones of fibrocartilage with irregular surface fibrillation. Soft tissue abnormalities consisting of osseous, chondroid, vascular, and fibrocartilaginous tissue have been reported in 76% of cases of melorheostosis.

Age at presentation varies widely and melorheostosis may be seen in children and adults. There is no sex predilection. The condition is often asymptomatic, but pain, stiffness and deformity may be present, with limitation of motion. The course of the disease is insidious, with a slow chronic progression of symptoms and periodic exacerbations.

Cortical hyperostosis is readily seen on plain radiographs. Soft tissue calcification or ossification may be seen. CT will also reveal the lesions and the clear demarcation between normal and abnormal bone. With MR imaging, bone and soft tissue lesions are usually low signal intensity on all pulse sequences, although a wider spectrum of imaging findings may be encountered with contrast enhancement. Scintigraphy reveals abnormal increased tracer uptake in the bone and soft tissue lesions.

In most cases of melorheostosis, biopsy is not needed for diagnosis. If performed, it is not diagnostic. Proper diagnosis is almost always evident on plain radiographs

References:

 Motimaya AM, Meyers SP.: Melorheostosis involving the cervical and upper thoracic spine: radiographic, CT, and MR imaging findings. AJNR Am J Neuroradiol. 2006 Jun-Jul;27(6):1198-200.

Lee CH et al.: Imaging of Melorheostosis : Emphasis on MR Imaging Findings. J Korean Radiol Soc 2000;42:333-339.

Resnick D.: Bone and joint imaging, 3 ed. Philadelphia: Elsevier-Saunders, 2005:1427-1430.

Greenspan A, Azouz EM. 1999. Bone dysplasia series. Melorheostosis: review and update. Can Assoc Radiol J 50(5):324-30. (http://www.orpha.net/data/patho/GB/uk-Melorheostosis.pdf)