We present the case of a 52-year-old male patient with a slowly growing paraspinal mass and a history of type 1 neurofibromatosis.
A 52-year-old patient with a known history of neurofibromatosis type 1 presented with a slowly growing paraspinal mass. Clinical evaluation revealed a large palpable mass at T12 to L4 on the left side.
Magnetic resonance (MR) imaging demonstrated a 15 cm mass arising from the left L2 spinal nerve and extending posteriorly to the paraspinal muscles. The lesion exhibited an inhomogeneous intermediate signal intensity on T1-weighted images, and a heterogeneous high signal intensity on T2-weighted images. Post-contrast T1-weighted MR images revealed a heterogeneous and mainly peripheral enhancement of the tumour, while its central necrotic section remained unenhanced after IV gadolinium administration. Multiple subcutaneous nodules were also noted likely representing neurofibromas.
Then, an ultrasound-guided biopsy was performed via a posterior approach using an 18-gauge biopsy needle. Pathological examination disclosed a malignant nerve sheath tumour with areas of necrosis.
Malignant peripheral nerve sheath tumours (PNST) are spindle cell sarcomas arising from peripheral nerve. Malignant PNSTs have also been referred to as neurofibrosarcomas, malignant schwannomas, neurogenic sarcomas, and malignant neurilemmomas [1]. They most frequently occur in 20- to 50-year-old patients, and represent 5 to 10% of all soft tissue sarcomas [1]. A significant proportion of malignant PNSTs are associated with type 1 neurofibromatosis [1]. Besides, secondary malignant PNSTs may arise from prior radiation treatment, with a latency period of more than 10 years. Malignant PNSTs generally involve the major nerve trunks, including the sciatic nerve, sacral plexus, and brachial plexus. Patients with malignant PNST present more frequently with pain, and neurological symptoms of motor weakness and sensory deficits, than do patients with benign PNSTs.
Malignant PNSTs can spread along the entering and exiting nerve, with the epineurium and perineurium becoming thickened proximal and distal to the lesion respectively. Histologically, the tumour cells are arranged in fascicles, sometimes mimicking fibrosarcoma; and areas of necrosis and haemorrhage are commonly observed [1].
Although malignant and benign PNSTs cannot be distinguished reliably by imaging criteria only, some findings should suggest a malignant tumour [2]. Malignant lesions tend to be larger (>5cm). They often exhibit ill-defined margins and associated oedema, related to infiltration of adjacent tissues. Heterogeneity with central necrosis on cross-sectional imaging, although it can be encountered in benign lesions, is suggestive of a malignant lesion. In the same way, significant differences between malignant PNSTs and neurofibromas have been identified for the largest dimension of the mass, peripheral enhancement pattern, perilesional oedema-like zone, and intratumoral cystic lesion [3,4]. The presence of two or more of these features suggestive of malignancy indicates a malignant PNST with a sensitivity of 61% and a specificity of 90% [3]. In addition, in cases associated with type 1 neurofibromatosis, heterogenicity on T1-weighted images is also significant in differentiating neurofibroma from malignant PNSTs [3].
Treatment of malignant PNSTs is surgical excision with wide resection margins. Adjuvant chemotherapy and radiation therapy are often associated to surgery. Local recurrence and metastases, most frequently affecting the lungs, bones, pleura and retroperitoneum, are frequent.
In conclusion, the MR features of a malignant PNST illustrated in this case were highly suspicious of malignancy and led to an imaging-guided biopsy for histological diagnosis.
Malignant peripheral nerve sheath tumour of the left L2 spinal nerve.
Based on the MRI images provided by the patient, a relatively large soft tissue mass is visible in the paravertebral region (either thoracic or lumbar, indicated by the arrow in the images). The mass demonstrates:
Additionally, certain degrees of surrounding soft tissue edema or infiltrative changes can be observed, which are often seen in malignant lesions.
Combining the patient's history (52-year-old male with a history of neurofibromatosis type 1) and the imaging features, the following diagnoses are considered:
Taking into account the patient’s:
In conclusion, the most likely diagnosis is Malignant Peripheral Nerve Sheath Tumor (MPNST). Final confirmation still requires correlating with pathological examination and relevant molecular biological tests.
Following surgical resection and subsequent therapies, patients often face localized soft tissue damage and a general decline in physical fitness. An individualized rehabilitation plan should take into account both surgical site healing and neuromuscular function recovery.
Special note: If the patient has additional systemic issues (such as osteoporosis or reduced cardiopulmonary function), a professional rehabilitation physician or exercise therapist should guide the process to ensure safety.
Disclaimer: This report is a reference analysis based on the available clinical and imaging data and does not replace an in-person consultation or professional physician’s diagnosis and treatment advice. Specific treatment plans should be determined by a specialist physician based on the patient’s actual condition.
Malignant peripheral nerve sheath tumour of the left L2 spinal nerve.
