Orthopedics

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Case Reports 

Solitary Pelvic Osteochondroma Causing L5 Nerve Root Compression

Whoan Jeang Kim, MD, PhD; Kap Jung Kim, MD, PhD; Sang Ki Lee, MD, PhD; Won-Sik Choy, MD, PhD

Abstract

Osteochondroma is the most common benign bone tumor, accounting for more than one-third of all benign bone tumors. It usually develops at the metaphysis of the long bones, especially the distal femur and proximal tibia. Approximately 40% of osteochondromas are found around the knee. Osteochondroma commonly presents as a painless mass and is incidentally identified via plain radiographs. Thus, surgical excision is not routinely recommended unless the tumor causes clinical symptoms or cosmetic distress.

Osteochondroma located in the pelvis is unusual. Spinal nerve root compressions due to pelvic osteochondroma are also rarely reported. We assessed the solitary pelvic osteochondroma of a 33-year-old man mimicking spinal disease. An exostotic bony projection composed of dense calcification of the cartilaginous cap arose from the iliac crest, which was located just lateral to the right sacroiliac joint in the paravertebral area, L5 level. Magnetic resonance imaging showed an irregular, exophytic outgrowing calcified mass with cartilage cap and exostotic mass compressed to the proximal part of the right L5 nerve root lateral to the nerve root foramen. The L5 nerve root was focally compressed and thinned.

En bloc excision, the treatment of choice of symptomatic osteochondroma, was performed. The patient had complete resolution of symptoms postoperatively, and other neurologic symptoms may be expected to improve over time.

Osteochondroma is the most common benign bone tumor, accounting for more than one-third of all benign bone tumors.1 It usually develops at the metaphysis of the long bones.2 Osteochondromas are classified as solitary or multiple.2 Solitary osteochondroma occurs at a single bone and is not hereditary. Multiple osteochondromas develop either spontaneously or in an autosomal dominant pattern described as hereditary multiple exostoses. Patients present during the second and third decades of life.2 Osteochondroma commonly present as a painless mass and is incidentally identified via plain radiographs. Thus, surgical excision is not routinely recommended unless the tumor causes clinical symptoms or cosmetic distress.

This article describes a case of symptomatic solitary pelvic osteochondroma causing L5 nerve root compression.

A 33-year-old man presented with right lower extremity radiating pain and paresthesia at the anterior skin of the lower leg of several months’ duration. The pain had worsened over the previous months. Nonsteroidal anti-inflammatory drugs provided minimal relief. He reported an intermittent limp shortly after arising from bed. The rest of his past history was unremarkable.

On physical examination, the patient was a healthy looking man. Neurologic examination revealed moderately decreased ankle dorsiflexion on the right side. Sensation was intact. Plain radiographs revealed an exostotic bony projection composed of dense calcification of the cartilaginous cap arising from the iliac crest (Figure 1), located just lateral to the right sacroiliac joint in the paravertebral area, L5 level.

Axial and coronal magnetic resonance imaging (MRI) showed an irregularly margined, exophytic outgrowing calcified mass with cartilage cap approximately 5×5×3 cm in size and exostotic mass compressed to the proximal part of the right L5 nerve root lateral to the nerve root foramen. The L5 nerve root was focally compressed and thinned (Figure 2).

Figure 1: Plain radiograph of the pelvis showing an exostotic bony projection with dense calcification of the cartilaginous cap arising from the iliac crest and just lateral to right sacroiliac joint, L5 level. Figure 2: MRI scans showing a bony mass at the right iliac crest adjacent to the sacroiliac joint (A) and the right L5 nerve root compressed by a lobulating bony mass just lateral to the right nerve root foramen (B).

En bloc excision was performed through the incision of the iliac crest. The tumor mass was completely excised in portions, leaving small residual defects (Figure 3). The exophytic…

Abstract

Osteochondroma is the most common benign bone tumor, accounting for more than one-third of all benign bone tumors. It usually develops at the metaphysis of the long bones, especially the distal femur and proximal tibia. Approximately 40% of osteochondromas are found around the knee. Osteochondroma commonly presents as a painless mass and is incidentally identified via plain radiographs. Thus, surgical excision is not routinely recommended unless the tumor causes clinical symptoms or cosmetic distress.

Osteochondroma located in the pelvis is unusual. Spinal nerve root compressions due to pelvic osteochondroma are also rarely reported. We assessed the solitary pelvic osteochondroma of a 33-year-old man mimicking spinal disease. An exostotic bony projection composed of dense calcification of the cartilaginous cap arose from the iliac crest, which was located just lateral to the right sacroiliac joint in the paravertebral area, L5 level. Magnetic resonance imaging showed an irregular, exophytic outgrowing calcified mass with cartilage cap and exostotic mass compressed to the proximal part of the right L5 nerve root lateral to the nerve root foramen. The L5 nerve root was focally compressed and thinned.

En bloc excision, the treatment of choice of symptomatic osteochondroma, was performed. The patient had complete resolution of symptoms postoperatively, and other neurologic symptoms may be expected to improve over time.

Osteochondroma is the most common benign bone tumor, accounting for more than one-third of all benign bone tumors.1 It usually develops at the metaphysis of the long bones.2 Osteochondromas are classified as solitary or multiple.2 Solitary osteochondroma occurs at a single bone and is not hereditary. Multiple osteochondromas develop either spontaneously or in an autosomal dominant pattern described as hereditary multiple exostoses. Patients present during the second and third decades of life.2 Osteochondroma commonly present as a painless mass and is incidentally identified via plain radiographs. Thus, surgical excision is not routinely recommended unless the tumor causes clinical symptoms or cosmetic distress.

This article describes a case of symptomatic solitary pelvic osteochondroma causing L5 nerve root compression.

Case Report

A 33-year-old man presented with right lower extremity radiating pain and paresthesia at the anterior skin of the lower leg of several months’ duration. The pain had worsened over the previous months. Nonsteroidal anti-inflammatory drugs provided minimal relief. He reported an intermittent limp shortly after arising from bed. The rest of his past history was unremarkable.

On physical examination, the patient was a healthy looking man. Neurologic examination revealed moderately decreased ankle dorsiflexion on the right side. Sensation was intact. Plain radiographs revealed an exostotic bony projection composed of dense calcification of the cartilaginous cap arising from the iliac crest (Figure 1), located just lateral to the right sacroiliac joint in the paravertebral area, L5 level.

Axial and coronal magnetic resonance imaging (MRI) showed an irregularly margined, exophytic outgrowing calcified mass with cartilage cap approximately 5×5×3 cm in size and exostotic mass compressed to the proximal part of the right L5 nerve root lateral to the nerve root foramen. The L5 nerve root was focally compressed and thinned (Figure 2).

Figure 1: An exostotic bony projection with dense calcification of the cartilaginous cap Figure 2A: A bony mass at the right iliac crest adjacent to the sacroiliac joint
Figure 2B: The right L5 nerve root compressed by a lobulating bony mass

Figure 1: Plain radiograph of the pelvis showing an exostotic bony projection with dense calcification of the cartilaginous cap arising from the iliac crest and just lateral to right sacroiliac joint, L5 level. Figure 2: MRI scans showing a bony mass at the right iliac crest adjacent to the sacroiliac joint (A) and the right L5 nerve root compressed by a lobulating bony mass just lateral to the right nerve root foramen (B).

En bloc excision was performed through the incision of the iliac crest. The tumor mass was completely excised in portions, leaving small residual defects (Figure 3). The exophytic mass had compressed the L5 nerve root just lateral to the nerve root foramen but they had not been adherent with each other. The excised tumor was composed of an irregular lobulated mass with cartilage cap. A subsequent pathology report showed no evidence of malignancy and was consistent with osteochondroma.

Figure 3: Postoperative radiograph showing complete removal of the tumor mass

Figure 3: Postoperative radiograph showing complete removal of the tumor mass.

Postoperatively, the patient’s radiating pain and paresthesia were completely gone, and neurologic symptoms were improved.

Discussion

Osteochondroma is the most common benign bone tumor, accounting for 10% to 15% of all bone tumors.1 They have cartilage-capped projections arising from the subperisoteum that develop from cartilage and enchondral ossification. The etiology of this tumor is unknown but thought to be either a congenital or traumatic defect of the perichondrium that results in herniation of an epiphyseal growth plate fragment. The majority of osteochondromas are solitary, and <1% tend to have malignant transformation. Less than 10% of multiple osteochondromas are found in a familial syndrome with an autosomal dominant pattern. Multiple osteochondromas have a tendency to be malignant for unknown reasons. Thus, surgical excision is considered in a familial pattern.

Osteochondromas are frequently found in long bones, especially the distal femur and proximal tibia. Approximately 40% of osteochondromas are found around the knee. Osteochondroma located in the pelvis is unusual. Dahlin and Unni1 reported that the incidence of solitary pelvic osteochondroma was 8% of a series of 640 patients. In a series of 37 patients with pelvic osteochondroma at the Mayo Clinic between 1910 and 1943, the initial symptoms were a palpable mass, local pain, a limping gait, a weak leg, and urethral discharge.3 In another report, pelvic osteochondroma presented with hematuria.4

Spinal nerve root compression due to pelvic osteochondroma is also rarely reported.5 Larson et al5 reported a case of L3 nerve root compression due to solitary pelvic osteochondroma.

In our case, we assessed the solitary pelvic osteochondroma mimicking spinal disease such as herniation of intervertebral disk. The initial study was a lumbar MRI. The diagnosis was readily available on plain radiographs. Our case was unusual in a number of ways. The patient’s age at presentation was older than the typical age group, and the location of his osteochondroma was unusual. The tumor had been growing for more than a decade with few symptoms. The patient’s osteochondroma resulted in L5 nerve root compression as evidenced by right lower extremity radiculopathy and paresthesia at the anterior skin of the lower leg. A slow-growing, multilobulated mass had been close to the L5 nerve root and eventually resulted in L5 nerve root compression and clinical symptoms.

Surgical en bloc excision is the treatment of choice of symptomatic osteochondroma. Our patient showed complete resolution of symptoms postoperatively, and other neurologic symptoms may be expected to improve over time.

References

  1. Dahlin DC, Unni KK. Bone Tumors: General Aspects and Data on 8,542 Cases. 4th ed. Springfield, IL: Charles C. Thomas Publisher, Ltd; 1986.
  2. Jundt G. Pathologic-anatomic characteristics of benign bone tumors [in German]. Orthopade. 1995; 24(1):2-14.
  3. Ghormley RK, Meyerding HW, Mussey RD Jr, Luckey CA. Osteochondromata of the pelvic bones. J Bone Joint Surg Am. 1946; (28):40-48.
  4. Phillips RR, Lee SH, Flannigan GM. Pelvic osteochondroma causing haematuria. Br J Urol. 1990; 66(1):99-100.
  5. Larson J, O’Malley JE, Cohen TI. Case report: solitary pelvic osteochondroma presenting with L3 nerve root compression. Alaska Med. 2002; 44(2):35-37.

Authors

Drs Kim (Whoan Jeang), Kim (Kap Jung), Lee, and Choy are from the Department of Orthopedic Surgery, Eulji University College of Medicine, Daejeon, Republic of Korea.

Drs Kim (Whoan Jeang), Kim (Kap Jung), Lee, and Choy have no relevant financial relationships to disclose.

Correspondence should be addressed to: Kap Jung Kim, MD, PhD, Department of Orthopedic Surgery, Eulji University College of Medicine, 1306 Dunsan-dong, Seo-gu, Daejeon (322-799), Republic of Korea (oskkj@eulji.ac.kr).

doi: 10.3928/01477447-20091020-25

10.3928/01477447-20091020-25

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