Dysplasia epiphysealis hemimelica (DEH), also known as Trevor disease, is an extremely rare, non-hereditary disease that is characterized by osteochondromas arising from the epiphyses.
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Epidemiology
The incidence is estimated at ~1:1,000,000 3. There is a recognized male predilection (M:F = 3:1). It usually presents in young children.
Pathology
Etiology
The etiology is uncertain but is thought to be congenital.
Location
the lower extremity is more common than the upper extremity
distal ends are more affected
medial aspects are affected twice as commonly as lateral
the distal femur is one of the most frequent sites
can occur around the ankle joint
Classification
Azouz et al. has proposed the following classification:
classic form: characteristic hemimelic distribution involving more than one bone or epiphysis within a single lower extremity
localized form: single bone affected (unilateral or bilateral)
generalized form: involves the whole limb from the pelvis to foot
Radiographic features
Plain radiograph
Typically shows an irregular mass with focal ossification arising from one side of the affected epiphysis 3. This can result in widening of the affected joint.
CT
Useful for assessing cortical continuity with the epiphysis.
MRI
MRI is useful for evaluation of underlying ligaments and cartilage. Osteochondral overgrowth signal intensity will be similar to normal epiphyseal cartilage and bone.
Treatment and prognosis
Treatment is surgical excision of the mass with preservation of the joint.
Complications
fragmentation and detachment leading to intra-articular bony fragments
deformation of the ligaments and tendons affecting the joint mechanism
chronic tendonitis and tenosynovitis due to chronic irritation of tendons by mass or bony fragments
development of secondary osteoarthritis of the affected joint
History and etymology
After French surgeon Albert Mouchet (1869-1963) and Joseph Belot (1876-1953) first described the condition in 1926 7, it was elaborated on by David Trevor (1906-1988), an English orthopedic surgeon from London 6,7. Later in 1956, Thomas John Fairbank (1912-1998) coined the name "dysplasia epiphysealis hemimelica" because of the medial or lateral half predisposition within a limb 7.