Forearm Giant Osteochondromas in a Young Patient With Multiple Hereditary Exostoses: A Case Report

Abstract

Multiple hereditary exostoses (MHE) is a rare skeletal disorder inherited as an autosomal dominant disorder. It is characterized by widespread multiple osteochondromas that grow near bone growth plates, leading to pain and deformities that significantly impact physical and emotional well-being and disrupt daily activities, social interactions, and psychological health, leading to considerable disability. This case report describes a 15-year-old boy with a family history of MHE who developed a large osteochondroma at his right elbow. We aim to present the surgical management of extraordinarily large-size proximal radius osteochondroma, fortunately, caused by a benign underlying condition despite typically carrying more chances of transformation into malignancy.‎ To the best of our knowledge, it would be the largest proximal radius osteochondroma documented in the literature.

Keywords: elbow; hereditary exostoses; large osteochondroma; proximal radial resection; radial head dislocation.

Figure 1. Tumor size.

(a and b): Indicating the site and the size of the tumor.

Figure 2. Preoperative plain radiograph, three-dimensional CT reformatted image, and MRI scan.

a. Preoperative plain radiograph of the right forearm showed an expansile bony lesion in the proximal end of the right radius with a dislocation of the radio-humeral joint and an increase in the bowing of the radial shaft. Additionally, there is evidence of distal radioulnar abnormal articulation as part of MHE. b. The preoperative three-dimensional CT reformat image showed an expansile bony lesion in the proximal end of the right radius with a dislocation of the radio-humeral joint and bone absorption in the lateral aspect of the humeral trochlea due to the abutment of the bony lesion. The ulna had no significant shortening or angular, varus, or valgus deformities. c. Preoperative MRI demonstrates a cauliflower-like bony outgrowth (Red circle) arising from the lateral metaphysis of the proximal radius (yellow circle), which measures approximately 51x41x48 mm. It shows preserved cortical and medullary continuity with the parent bone. The cartilaginous cap thickness measures about 3 mm. (Green circle= proximal ulna) (Light blue circle= forearm flexors muscles) (Dark blue circle= mobile wad muscles) (Red arrow= neurovascular bundle).

Figure 3. Intraoperative Steps: Skin approach, tumor exposure, posterior interosseous nerve identification, and fascial strip application.

a. Shows an extended lateral skin approach directly over the lesion. b. Demonstrates the tumor exposure by the elevation and the dorsal reflection of the fascio-muscular flap. c. Illustrates the location and the integrity of the posterior interosseous nerve. d. A fascial strip was warped around the radial shaft.

Figure 4. Size of the resected sample.

Images a and b indicate the size of the resected sample, which is 7 cm wide and 6 cm long.

Figure 5. One-year postoperative plain radiograph.

One-year postoperative plain radiograph of the right elbow joint showed mild elbow valgus deformity with no radial shaft proximal migration or tumor recurrence.