Case report of bilateral dysplasia epiphysealis hemimelica (DEH) of talus

A 5-year and 4-month-old boy consulted our hospital with left leg pain, caused by torus fracture of the distal tibia. During the treatment, both his flat feet and a slight bony prominence in both medial sides of the talus were noticed. There was neither pain nor discomfort at his foot bottom.

Flatfoot and valgus deformity of calcaneal were found (Fig.1). Plane X-ray pictures revealed deformity of the talus and bony protrusions at the medial side of the talus with a slight punctate change as a mirror lesion in both tali (Fig 2, 3). His younger sister’s plain AP radiograph of both ankles showed almost the same bony protrusion formation in the medial side of both tali (Fig.4). Other relatives, including parents had no special notes. MRI revealed an iso-intense mass covered by cartilage arising from both the medial side of the talus neck and the head in T1-Weighted image and T2-Weighted image (Fig.5). Abnormal intensity, indicating suspicion of malignancy, was not detected. The talo-navicular joint was delineated between the deformed head of the talus and the navicular. No dislocation of the talo-navicular joint was found (Fig.6).

Background
DEH was first reported by B. J. Mouchet A in 1926. In 1950, Trevor D. reported DEH using the term Tarso-epiphyseal aclasis. In 1956, Fairbank first used the term dysplastic epiphyseal hemimelica [1]. DEH is a rare developmental disorder of epiphyseal osteocartilaginous growth. Usually an osteocartilaginous mass arises from one side and on the medial side of the body. It most often presents at the knee and ankle; involvement of the upper extremities is rare. Aetiology and heredity are unknown. The incidence has been reported as one per million. The ratio between boys and girls is 3:1. DEH has the following three different types: local, classic and generalised types. In the current case, the local type would be applicable, but “bilateral local type” might be a more proper category. The word ''hemimelica'' is derived from two greek words: ''hemi'' meaning half and ''melos'' meaning limb. Nothing in the name would prevent applying it to bilateral lesions.

Clinical perspective
There are only 5 case reports we could find in the past, including one case of both tali lesions [2, 3, 4, 5]. Those locations, the presence of a mirror lesion, radiographic, MRI and pathological findings and comorbidity were shown in Table 1. By the place that a tumour produces, the symptoms are various. Sometimes the clinical symptom is deformity or stiffness of the ankle, knee, and so on. Sometimes it will be pain. In the present case, the only symptom is hump and flat feet deformity. There was no pain nor stiffness.

Imaging perspective
Regarding radiological characteristics, an irregular mass containing punctate ossificasion arising from the epiphysis is typically detected. During the infant or toddler age, it may be only an epiphyseal widening. At adolescent or adult age, an irregular bone mass, containing multi-centric radiodensity is seen. Gradually, the mass becomes adhesive to normal bone. In the current case, radiological findings were close to the ones typically found in the older age group, rather than in the younger age category. MRI showed iso-intensity bony mass covered with cartilage.

Outcome
Treatment of DEH varies depending on location, severity, symptoms, dysfunction, deformity and so on. If there are mild symptoms, deformities, or dysfunctions, conservative therapy will be chosen (like an arch support applied for flat foot in the current case). Operative treatment will be considered if there is persistent pain related to the deformity and/or dysfunction of the adjacent joint.