A case is presented of a large,incidental ,paravertebral fat containing tumour in a patient with recurrent symptoms following spinal surgery
A 44 year-old male ,who had a previous L5/S1 spinal fusion for degenerative spondylolisthesis , presented with recurrent low back pain and MRI was performed .This showed a large soft-tissue mass on the left side of, and adjacent to, the spinous process of L2 which had the same signal characteristics as subcutaneous fat on all sequences (fig. 1).Linear areas of low signal on both T1 and T2 weighted images , which were in continuity with the spinous process, extended into the mass.The cauda equina was normal and the L5/S1 fusion had consolidated (not shown). Review of radiographs showed hyperostosis of the L2 spinous process (fig. 2). CT confirmed the presence of a large fatty tumour closely applied to the L2 spinous process with associated hyperostosis traversing the tumour (fig. 3) Further non-ossified linear areas of soft-tissue streaking within the tumour visible on CT were interpreted as fibrovascular septa.The imaging features were typical for a parosteal lipoma and a biopsy was not performed.
Lipomas are common ,benign tumours containing adipose tissue .They are most commonly found in the subcutaneous tissues but also occur in intra-muscular,intra-osseous and parosteal locations. Parosteal lipomas are rare and account for 0.3% of all lipomas (1) .The term parosteal implies that they are adherent to the periosteum although it is debatable if they originate from the periosteum itself. In addition to fat ,variable amounts of fibrous tissue and bone are present within the tumour, resulting either from metaplasia in fibrofatty tissue or from “stimulation” of the adjacent periosteum (2).They can be classified according to the pattern of these non-fatty elements . Typically a parosteal lipoma presents as a large, painless ,immobile mass in a middle-aged patient. Males and females are affected equally and the femur and radius are the commonest sites of involvement .The spine is rarely involved. Radiographs typically show a clearly marginated , radiolucent soft-tissue mass adjacent to the cortical surface. Spicules of bone extend from the cortex into and around the fatty component producing a characteristic appearance .Other bone changes may include bowing deformity or cortical erosion. CT clearly demonstrates both the fatty and osseous elements. Fibrovascular septa within the tumour may be visible as soft-tissue-density strands. CT is helpful in confirming the presence of fat in areas which are difficult to image radiographically ,for example the hip and spine , and in confirming the parosteal location distinguishing it from a deeply located soft-tissue lipoma which is separated from the cortical surface by normal tissues (3). At MRI the fat component has the same signal characteristics as subcutaneous fat on all sequences and contains areas of low signal intensity which correspond to the fibro-osseous elements (4).The multiplanar imaging capability of MRI is a considerable advantage over CT in the pre-operative planning of large or complex lesions (1). The diagnosis of parosteal lipoma is important in distinguishing it from other proliferative and more aggressive periosteal lesions,for example parosteal sarcoma(2). Surgical resection is often difficult because they are usually firmly adherent to the periosteum and may require the use of an osteotome or segmental resection of the underlying bone (1).
Paravertebral parosteal lipoma.
Based on the provided CT, MRI, and X-ray images, a relatively large soft-tissue mass can be observed in the paravertebral region (next to the vertebral column), primarily showing fatty density/signal with a well-defined border. On CT images, the fatty-density mass is located near the vertebral body, and irregular or patchy bone shadows are visible within the tumor or at the interface between tumor and bone cortex, connected to the bone cortex. On MRI, the main tumor signal is similar to subcutaneous fat (high signal on T1-weighted images and also high on T2-weighted images), with some low-signal septa or patches (corresponding to fibrous or bony components). On the X-ray, a radiolucent region (fat density) near the vertebral body can be seen along with spotty or patchy sclerotic areas (ossification or bone spurs) connected to the cortex, suggesting a periosteal process continuous with bone. The lesion is relatively large and slightly lobulated, closely adjacent to the vertebral body or paravertebral bone, indicating adhesion or attachment to the periosteum. Overall, the imaging features suggest a benign lesion with fatty components and osteogenic/ossified elements.
Considering the patient’s age (44-year-old male), clinical presentation (recurrent back discomfort or postoperative recurrence), and imaging features (a local fatty-density mass attached to the periosteum with associated bone formation/bone spurs), the most likely diagnosis is:
“Paravertebral Parosteal Lipoma.”
This lesion is a relatively rare benign tumor that can sometimes cause pain or compression symptoms due to its local growth. Because it is tightly adhered to the periosteum, surgical removal often requires careful stripping of bone or partial bone resection.
During treatment or conservative management, to maintain or improve spinal biomechanical balance, promote muscle function recovery, and enhance strength, an individualized exercise prescription can be developed following the FITT-VP principle (Frequency, Intensity, Time, Type, Progression, and Volume):
Throughout the rehabilitation process, it is important to regularly assess the patient’s skeletal stability, muscle condition, and cardiorespiratory status to ensure both safety and effectiveness of training. In the event of increased pain or neurological symptoms, prompt re-evaluation and plan adjustments are necessary.
Disclaimer: This report is based on the current imaging and clinical history for reference only. It cannot replace an in-person consultation or professional medical advice. Specific diagnoses and treatments must be comprehensively determined by a specialist based on clinical manifestations and further examinations (for example, pathological analysis).
Paravertebral parosteal lipoma.
