Of all spinal tumors, 70% of primary bone tumors are benign . Osteochondromas (exostoses), which represent up to 7% of the benign spinal tumors , are a benign outgrowth of bone covered by a cartilaginous cap [8, 12], which could present as either a solitary lesion or as multiple lesions that occur either spontaneously or in an autosomal dominant pattern known as hereditary multiple exostoses (HME) .
Spinal osteochondromas occur more frequently in the cervical spine and upper dorsal segments, with lumbar osteochondroma, which is least affected ; they commonly arise in the pedicles, the lamina, or in the vertebral body . The relative rareness of lower lumbar osteochondromas is believed to be due to less flexibility of the lumbar region compared to the cervical, which gives the lumber area greater resistance to epiphyseal growth cartilage displacement (which is believed to be the reason for osteochondroma development) .
In a review of literature by Yakkanti et al.  where they evaluated 84 articles reporting on 149 cases (123 (88.6%) were solitary, and 17 (11.4%) were associated with MHE), for the solitary lesions as the one reported in the current case, the most common region of affection was the cervical spine 63 (52.2%) of the cases, followed by the lumbar region 35 (26.5%), the posterior element was the commonest origin of the lesion with 85 cases (64.3%). For the lumber spine affection, four cases were reported to affect L5 vertebrae, one affecting the lamina , two affecting the body [15, 16], and in one case, the location was not reported .
Lumbar osteochondromas can cause various symptoms depending on their location, commonly related to the mechanical effects of the lesion leading to neurological symptoms (if it is growing inside the canal or compressing a nerve root) in the form of radiculopathy, myelopathy, cauda equina syndrome, foot drop, or neurogenic claudication [4, 8, 10].
Albrecht et al. suggested that plain radiographs are not conclusive for definite diagnosis ; further imaging modalities should be utilized, commonly a CT and MRI [3, 4, 15]. The CT scan will define the origin of the mass and help define the anatomical landmarks needed for planning the surgical excision . In contrast, the MRI will be beneficial for measuring the cartilage cap’s thickness, assessing the surrounding neural tissues, and if a suspected malignant transformation needed to be ruled out .
Surgical resection of a lumbar osteochondroma is the management option of choice, especially if the patient is presented with symptoms; this surgical excision could be in situ marginal or wide excision, via a posterior, anterior, or combined approach, according to the location and the size of the mass [3, 6]. In case of development of neurological symptoms, surgical excision with decompression of a nerve root or the neural canal should be performed, with instrumented stabilization with or without fusion according to the spine stability after lesion resection [3, 14, 15].
Although it is fortunately rare, malignant transformation is considered the most concerning complication, with an estimated risk of transformation of about 1% for solitary osteochondroma and up to 5% for multiple osteochondromas . Malignant transformation should be suspected if the cartilaginous cap is more than 3 cm, when patients report new onset of symptoms, and when the mass rapidly increases in size .