Age / Sex : 58 / F

Chief complaint: localized soft tissue swelling

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Courtesy: Jee Young Kim, St. Vincent’s Hospital, Catholic University of Korea

Melorheostosis

Discussion

Findings

Plain radiograph. An ovoid calcific nodule located in juxtacortical area of carpal bone (arrow)

Distal radius has a flowing, eccentrically located ossification (arrow head).

Coronal and sagittal T1-weighted MR images show a juxtacortically located, low SI ovoid mass with focal intramedullary invasion in trapezium (arrow). There is no evidence of abnormal SI in bone marrow of trapezium. There is another low SI lesion of flowing, eccentrically located ossification in distal radius (arrowhead).

Differential diagnosis:

Bizarre parosteal osteochondromatous proliferation on plain radiograph

Diagnosis:  Melorheostosis

Discussion :

Melorheostosis is a rare bone disorder, and usually manifests after early childhood. Occasionally, patients in the fourth and fifth decades of life may reveal.

Initial manifestations are intermittent swelling of joint, pain and limitation of motion.

Radiographic findings are highly characteristic. Changes commonly are limited to a single limb, in which one or more bones may be affected. Peripheral located hyperostosis is evident in one bone or a series of bones. The appearance of the osseous excrescences extending along the length of the bone simulates that of candle wax flowing down the side of a lit candle. A wavy and sclerotic bony contour is produced that may involve one side of the tubular bones of the upper or lower extremity, reaching the carpus and tarsus as well as the metacarpals, metatarsals, or phalanges. Endosteal hyperostosis is an associated feather that may partially or completely obliterate the medullary cavity. In the carpal and tarsal areas, more discrete round foci may resemble the findings of osteopoikilosis, whereas in the flat bones, such as those in the pelvis, or the scapula, radiating or localized sclerotic patches are seen. Bone masses may protrude into adjacent articulations, appearing as osteochondroma-like lesions, Soft tissue calcification and ossification are not infrequent, have a predilection for paraarticular regions, and lead to complete ankylosis of the joint. Scintigraphy in cases of melorheostosis can reveal areas of increased skeletal accumulation of radionuclide. With MR imaging, bone and soft tissue lesions are of low signal intensity on all pulse sequences.