Enchondroma is a slow-growing tumor and can develop at any part of the vertebra, including spinous process, lamina, pedicle, and vertebral body [1]. Nevertheless, posterior elements are more likely to be affected than other locations [5]. Enchondroma originates from the medullary cavity and usually grows inside the bone without cortex penetration [3, 4]. Neurological symptoms may develop gradually as the tumor grows and compresses the neural elements.

Enchondroma usually occurs in a solitary fashion [1]. The presence of multiple enchondromas is highly indicative of the diagnosis of enchondromatosis syndrome, such as Ollier disease and Maffucci syndrome [6, 7]. Ollier disease is a rare condition in which multiple enchondromas appear in the large and small tubular bones of limbs, usually with a unilateral predominance [6]. When associated with soft tissue hemangiomas, the disease is known as Maffucci syndrome [7]. Although the individual lesions are similar to solitary enchondromas, the risk of sarcomatous degeneration may be as high as 25% in patients with Ollier disease and Maffucci syndrome [1].

Plain radiographs of the spine are difficult to identify an enchondroma. CT scan is of help to clearly visualize the pathology and its relation to adjacent bones [3]. A radiolucent, erosive lesion can be revealed on a CT scan of bone setting. Stippled or scattered patterns of calcification inside the tumor may be present. MRI is useful in making diagnosis and distinguishing between benign and malignant lesions. Chandramohan et al [8] found that most chondromas demonstrated intermediate signal intensity on T1-weighted images and high signal intensity on T2-weighted images. Calcified cartilage with sporadic osseous content typically shows mixed low to high signal intensity on T2-weighted images. Peripheral rim enhancement on MR images after Gd-DTPA administration has been reported in chondromas as a feature for benign cartilaginous tumors [5]; however, in large chondromas, this phenomenon may not be apparent [2].

Grossly, enchondroma appears as lobules of firm, mature cartilage, with regions of grittiness signifying mineralization of the matrix [9]. Histologically, enchondroma is composed of neoplastic chondrocytes dispersed within an abundant hyaline or myxoid background [5]. The tumor cells may be arranged in a pseudolobular fashion, with foci of calcifications depositing in the lacunae. Exhibition of nuclear atypia and cellular mitosis is rare.

Surgical excision is generally recommended as the treatment of choice for cases with local and/or neurological symptoms. [1] The goal of surgery is to establish a histological diagnosis, prevent sarcomatous degeneration, and preserve neurological function. Recurrence of chondroma is less than 10% after surgery, and usually related with incomplete removal [2, 5, 10]. In cases in which excision results in spinal instability, the spine must be instrumented or reconstructed.

We report a rare case of large enchondroma in the thoracic spine presenting severe upper back pain in a 49-year-old woman. Despite its benign-growing nature, enchondroma should be examined closely for signs of multiple enchondromatosis and enchondrosarcoma. Complete surgical resection is the treatment of choice for immediate relief of symptoms and avoidance of recurrence.