Malignant Peripheral Nerve Sheath Tumor Presenting as Horner's Syndrome

Abstract

Malignant peripheral nerve sheath tumor (MPNST) is a rare, aggressive sarcomatous tumor that arises from peripheral nerve sheath and shows Schwann cell differentiation. They are commonly seen among cases with existing benign plexiform neurofibromas, prior radiation treatment, and large germline mutations involving the entire neurofibromatosis 1 (NF1) gene. MPNST can have varied presentations; hence diagnosis remains a great challenge. Here we report a rare case of MPNST in an NF1 patient who presented with Horner´s syndrome. A young male reported swelling in the neck, dyspnea on exertion, and dysphagia. Subsequently, he was diagnosed to have a malignant peripheral nerve sheath tumor arising from the mediastinum and compressing the ipsilateral cervical sympathetic plexus causing Horner's syndrome. The patient underwent surgical resection of the mediastinal mass followed by chemotherapy. His symptoms improved significantly following treatment. This case report emphasizes the fact that high suspicion of MPNST is required when NF1 cases present with mass lesions, so that early surgical clearance with chemoradiation may offer a near-complete cure.

Keywords: brachial plexopathy; horner’s syndrome; malignant peripheral nerve sheath tumour; neurofibromatosis 1; sarcoma soft tissue.

Figure 1. Clinical and radiological findings.

The clinical photograph (A) shows multiple nodules over the chest wall, arms, and forearms consistent with neurofibromatosis. (B) shows a large swelling over the anterolateral aspect of the neck on the left side. (C) shows meiosis and partial ptosis of the left eye. CT scan shows a large lobulated mass (red arrow) compressing the trachea (yellow arrow) giving a slit-like appearance (D).

Figure 2. Histopathological examination.

Fine needle aspiration cytology from the neck swelling (May Grunwald-Giemsa stain 40x magnification) showed spindle-shaped cells (black arrow) with fibromyxoid stroma (A). Histopathological examination of biopsy from the swelling (H&E stain) showed spindle cells with wavy nuclei, nuclear pleomorphism with infrequent mitotic figures, consistent with low-grade malignant peripheral nerve sheath tumor (B).