Malignant peripheral nerve sheath tumor with extensive osteosarcomatous and chondrosarcomatous differentiation: A case report

• MPNST is an aggressive tumor especially in younger age group and even if there is no association with NF1 gene.
• Distant metastasis may appear within 1 year of radical R0 resection of the primary tumor.
• Exhibition of divergent differentiation may be associated with poor prognosis.
• Metastatic MPNST may not exhibit divergent differentiation similar to that exhibited by the primary tumor. This interesting finding warrants further research and analysis to establish its impact on the prognosis.

BackgroundMalignant peripheral nerve sheath tumor is an uncommon tumor of the peripheral nerves. The commonest presenting symptom is soft tissue mass and pain with local neurological findings. Imaging modalities are unhelpful in making a reliable diagnosis. Treatment is radical resection with adequate clear resection margins. Radiotherapy improves the local control, but the prognosis remains poor especially in those with divergent differentiation.SummaryA 23-year-old man with no history of neurofibromatosis presented with a swelling on the back which has been gradually increasing in size and causing him discomfort. The tumor was surgically excised and the histopathological examination revealed malignant peripheral nerve sheath tumor with extensive osseous and cartilaginous differentiation. He developed pulmonary metastases one year after the surgical resection. Pulmonary metastatectomy was therefore performed and the histopathology of the metastatectomy specimen revealed metastatic malignant peripheral nerve sheath tumor, but without any osseous or cartilaginous differentiation. He remained well with no recurrence or metastases at 9-month follow-up.ConclusionMalignant peripheral nerve sheath tumor is a malignant tumor that behaves aggressively despite adequate radical resection. This case also illustrates extensive osseous and cartilaginous divergent differentiation of the primary tumor which was surprisingly absent in the metastatic lesions. This finding warrants further research.