dysplasia

Dysplasia Epiphysealis Hemimelica

Elizabeth Badowski, CNP

Nationwide Children’s Hospital, Columbus, Ohio

A 6-year-old girl presented to a pediatric orthopedic surgeon for evaluation of a prominence below her right knee. The child’s pediatrician had observed the mass approximately 8 months ago. Since then, it had increased slightly in size. The pediatrician had obtained anteroposterior and lateral knee radiographs, with a report suggestive of a soft-tissue prominence of the anterior tibial tubercle, most likely representing a “tug lesion” due to repetitive trauma (A).

Throughout the course of monitoring by the pediatrician, the girl was reported to have been otherwise a healthy, normal-acting child with no complaints of pain. No limitations in function or activity had been reported. Past medical, surgical, and family histories were noncontributory, and no medication use had been reported.

After continued observation, along with the radiography results and the enlarging of the mass, the pediatrician initiated orthopedic referral.

On clinical examination, the girl denied pain with movement of the right lower extremity at both the knee and the ankle. She had full range of motion of the right knee, with the ability to extend and flex the right knee past 90°. Symmetrical motion and knee stability were noted. No obvious deformity and no limp with ambulation were noted. A well-circumscribed, quarter-sized, fixed, firm mass could be palpated on the right anterior proximal tibia. The mass was without redness, swelling, or fluctuance. No pain was elicited with palpation of the lump, and the right lower extremity showed an intact neurovascular status.

Magnetic resonance imaging (MRI) scans, obtained before the orthopedic appointment, revealed an approximately 7 × 22-mm osteochondroma contained within and attached to the anterior proximal right tibia (B and C).

dysplasia

An osteochondroma, also called an exostosis, is a common skeletal tumor that accounts for 20% to 50% of benign bone tumors.1 An osteochondroma is considered a cartilage-capped bony projection on the external surface of a bone.2 The prevalence is slightly greater in boys, affecting them 2 to 3 times more often than girls.3 Osteochondromas often are a solitary bone tumor and most commonly involve the metaphysis of long bones, particularly the knee (40% of lesions) and proximal humerus.1

The unique location of this patient’s osteochondroma confirmed the diagnosis of dysplasia epiphysealis hemimelica (DEH), or Trevor disease. This condition is an uncommon developmental abnormality in young children that is characterized by unilateral eccentric overgrowth of an epiphysis,4 most commonly seen in the distal femur, proximal tibia, talus, and tarsal navicular.5 DEH is a very rare disease, with an estimated incidence of 1 in 1 million.4

In DEH, the epiphyseal growth of the osteochondroma continues until skeletal maturity, with the increase in size causing joint destruction, particularly to weight-bearing surfaces of joints.6 The ossification centers of affected bones usually appear early, resulting in premature epiphysis closure. This may lead to leg-length discrepancy, genu valgum, and other lower limb deformities.5,7

Treatment options range from observation to surgery. Observation is warranted if the patient is asymptomatic and an angular deformity has not occurred. If the lesion is painful, if deformity has occurred, or if joint function is limited, then surgery usually is performed.5 Recurrence is common, however, and often more than one surgical procedure is needed. In addition, surgical outcomes are not as successful if the lesion is intra-articular.5

This patient initially was treated with observation, since the lesion was asymptomatic and surgical excision posed a significant risk of physeal arrest, given her age. At the 4-month follow-up visit, although the girl’s mother believed that the lesion had enlarged somewhat, results of the clinical examination and radiographs were unchanged. Therefore, the plan was for continued observation, with the girl returning in 1 year for another physical examination and radiographs of her right knee.

References

1. Erol B, Dormans JP. Musculoskeletal tumors in children. In: Dormans JP, ed. Core Knowledge in Orthopaedics: Pediatric Orthopaedics. Philadelphia, PA: Elsevier Mosby; 2005:290-336.

2. Hill CE, Boyce L, van der Ploeg ID. Spontaneous resolution of a solitary osteochondroma of the distal femur: a case report and review of the literature. J Pediatr Orthop B. 2014;23(1):73-75.

3. Volders D, Vandevenne JE, Van de Casseye W. Trevor’s disease and whole-body MRI. Eur J Radiol. 2011;79(3):363-364.

4. Vogel T, Skuban T, Kirchhoff C, Baur-Melnyk A, Siegert S, Heimkes B. Dysplasia epiphysealis hemimelica of the distal ulna: a case report and review of the literature. Eur J Med Res. 2009;14(6):272-276.

5. General principles of tumor management. In: Herring JA, ed. Tachdjian’s Pediatric Orthopaedics: From the Texas Scottish Rite Hospital for Children. Vol 2. 5th ed. Philadelphia, PA: Elsevier Saunders; 2013:1079-1082.

6. Grogan DP. Dysplasia epiphysealis hemimelica. Medscape. http://emedicine.medscape.com/article/1257694-overview. Updated January 10, 2013. Accessed June 11, 2014.  

7. Tyler PA, Rajeswaran G, Saifuddin A. Imaging of dysplasia epiphysealis hemimelica (Trevor’s disease). Clin Radiol. 2013;68(4):415-421.