Dysplasia Epiphysealis Hemimelica (Trevor Disease) of the Talus in a Toddler: A Case Report With a Long Follow-up

Abstract

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Introduction

Dysplasia epiphysealis hemimelica (DEH) is a rare congenital growth disorder characterized by an enchondral ossification abnormality and by the presence of accessory cartilage nuclei. ³ This results in altered bone development, asymmetrical growth, axial deviations, limb length discrepancy, and early onset of osteoarthritis. The lower limb, particularly the talus, is most affected. It predominantly affects children between 1 and 4 years old and may manifest as a firm, painless swelling that can progressively deform the joint and limit joint mobility.^1,4

Histologic examination reveals disordered cell proliferation in the accessory nuclei, without malignant degeneration.

In literature, cases diagnosed at an early age and particularly within the first 3 years of life are rare ¹ ; more commonly, in the past, diagnosis was delayed until clinical examination revealed joint deformities, axial deviations, and functional limitations.

This case report describes a toddler in whom the diagnosis of DEH was made at 29 months of age, and the treatment that was concurrently adopted.

Case Report

A 29-month-old child presented to our clinic with a left valgus hindfoot and swelling below and behind the medial malleolus, characterized by a hard-elastic consistency adhering to deep planes. Conventional radiographic examination revealed a heterogeneous, radio-opaque structure posterior to the talus nucleus, displaying irregular contours. Magnetic resonance imaging examination, conducted under sedation, exhibited a neoformation with an osteocartilaginous structure and a substantial cartilaginous component. The benign features of the neoformation and its characteristic, albeit rare, location facilitated a nearly definitive diagnosis of DEH (Figure 1).

Figure 1.

Twenty-nine-month-old boy affected by dysplasia epiphysealis hemimelica (Trevor disease) of the left talus. (A) Clinical appearance with swelling of the medial submalleolar (dashed arrow) and retromalleolar (arrow) region. (B) Preoperative lateral-view radiograph showing accessory bone nuclei posteriorly. (C) Preoperative sagittal fat-saturated proton-density–weighted MRI showing bone tissue and cartilaginous tissue (arrow) inside the talus body. (D) Preoperative transversal T2-weighted MRI showing the posteromedial located lesion of the talus. MRI, magnetic resonance imaging.

The Cincinnati approach was adopted for its suitability to address the lesion's location in the medial retromalleolar region, its size, and the need to safeguard the neurovascular bundle. ²

The excision of the osteocartilaginous neoformation was performed while preserving the macroscopic morphology of the talus and with the assistance of a fluoroscope, ensuring the removal of lesions highlighted by radiography (Figure 2).

Figure 2.

Surgical procedure. (A) Shortened “Cincinnati” approach to the hindfoot identifying the neurovascular bundle located over the lesion. (B) To expose the tumor, the neurovascular bundle was pulled plantarly whereas the tibialis posterior and flexor digitorum longus tendons were lifted anteriorly. (C) Macroscopic appearance of the lesion with typical translucent cartilaginous surface. (D) Removal of the lesion inside the talus body. (E) Ankle joint mobility and congruity were tested after lesion removal. (F) Postoperative radiograph.

Histologic analysis of hematoxylin and eosin-stained sections demonstrated chondroid overgrowth without classical features of chondrocyte maturation. This was characterized by clusters of hypertrophic chondrocytes with minimal to no cytologic atypia (Figure 3).

Figure 3.

Histologic examination of the resected specimen. (A) Hematoxylin and eosin staining showed at low magnification a chondroid proliferation (arrow) on the surface of the sample, whereas in the internal part trabecular bone (dashed arrow) and medullary spaces (star) were present. Insert represents clusters of hypertrophic chondrocytes. Bar = 500 µm. (B) Safranin O staining typically marks cartilaginous tissue. The image highlighted disorganized chondrocytes embedded in a great amount of collagen (in red, arrow), faced by trabecular bone (in blue, dashed arrow) and medullary spaces (star). Bar = 200 µm.

The child was immobilized for 1 month in a plaster cast. Routine clinical evaluations were conducted at 5 days, 2 weeks, 1 month, 3 months, 6 months, 1 year, and annually until the age of 10 years. No recurrence at the surgical site, axial deviations, or joint deformities were observed, and full range of motion was maintained.

Nineteen years after the surgery, at the age of 21 years, the patient, now working as a metalworker, was contacted for a clinical assessment. Asymptomatic, he exhibited no swelling or functional limitations and reported being highly satisfied. The scar was faint with minimal discoloration. With consent obtained, radiographs were performed, revealing a nearly anatomical shape of the talus except for a slight depression of the posterior aspect of the talar dome, nonetheless showing excellent joint congruence, with no signs of arthritis in the tibiotalar joint or adjacent joints (Figure 4).

Figure 4.

Clinical, functional, and radiologic outcomes at a 19-year follow-up. (A) Normal ankle and foot alignment. (B) Normal ankle range of motion: extension (C) Flexion. (D) Normal scar over the achilleas tendon (arrows). (E) Slightly discolored scar medially (arrows). (F) Ankle radiograph in lateral projection. Normal talus shape and normal tibiotalar congruity. (G) Anteroposterior ankle radiograph showing an irregular talar dome profile with a minimal central dip.

Discussion

DEH is a rare form of osteochondrodysplasia characterized by the presence of accessory ossification nuclei. Treatment typically focused on addressing these secondary issues rather than curing the underlying pathology. ¹

Conventional radiography, although useful in guiding diagnosis of DEH, primarily depicts mineralized bone tissue and does not provide assessment of cartilaginous structures. In contrast, MRI enables visualization of both bone and cartilaginous structures.^5,6 In this case, MRI facilitated the diagnosis of DEH and localization of the lesion within the context of the talus.

The decision for surgical treatment was influenced not only by the need for histologic confirmation of the diagnosis but also by the recognized progression of this joint lesion, which may lead to altered joint congruence, bone deformity, axial deviations of the limb, and functional limitations. ¹

The surgical approach described by Crawford et al ² involves an incision that provides improved visualization of the medial, posterior, and lateral aspects of the foot and ankle, resulting in excellent wound healing and enhanced cosmetic appearance compared to more commonly used vertical incisions. The extensive exposure of structures allowed for visualization and isolation of the neurovascular bundle, identification of the lesion in the retromalleolar region near the neurovascular bundle, and macroscopic evaluation of its extent. The bundle was indeed more superficial with respect to the lesion (Figure 2). Therefore, it was necessary to move the bundle and the tendons of the posterior tibialis and flexor digitorum communis to expose the lesion. The comprehensive view of the site enabled assessment of the anomalous posterior profile of the talus. Depth-wise, as highlighted by MRI, there was a demarcation line with the talus itself. Intraoperative radiography did not reveal the presence of additional accessory nuclei within the cartilaginous tissue context.

Clinical evaluation during follow-up until 10 years of age did not reveal any deformities, functional limitations, or axial deviations of the ankle. In a recent literature review comprising 70 cases of DEH of the foot and ankle, the average age at surgical treatment was 9.6 years, with only 5 patients having undergone surgery before the age of 3 years. Even when diagnosis was early, surgical treatment was often delayed because of concerns about potential secondary osteoarthritis or recurrence. For this reason, some authors preferred observation for small and asymptomatic lesions. ¹ In the case presented here, there was a positive evolution of the clinical picture without the typical consequences of incomplete lesion removal, such as axial deviations and early arthritis. Radiographic evaluation 19 years later showed joint congruence and a normal joint space despite a slight deformity of the talus dome.

Conclusions

This case report highlights the importance of early diagnosis and treatment in DEH. A 29-month-old male child underwent an early surgical treatment using a transverse extensive incision with resection of accessory nuclei and cartilaginous tissue in the posterior part of the talus. At long-term follow-up at an age of 21 years, the patient showed normal range of motion of the ankle joint without joint deformity or axial deviations and almost normal radiologic outcome.