Case 010 - 7 Year Old Female with Left Neck Mass
on the Scalp
Contributed by Diana Padgett, M.D., Supervised by Olga Lasater, M.D.
The patient is a young girl with neurofibromatosis, type I, who presented with pain and progressive myelopathy. On imaging, she was found to have a soft tissue mass extending from the left brachial plexus through the cervical vertebrae into the epidural space, with consequent spinal cord compression. The lesion was resected.
Received is a 1.50 gram, 2.5 x 1.5 x 0.5 cm aggregate of red-brown to gray-white, soft to rubbery fragments.
(Click a photo to view a larger image.)
Malignant Peripheral Nerve Sheath Tumor (MPNST)
Microscopically, the tumor consisted of a plexiform neurofibroma intermingled with a population of pleomorphic, hyperchromatic spindled cells with abundant mitotic activity. In addition, heterologous elements, including apparent cartilage were present. By immunohistochemistry, the pleomorphic cells demonstrated areas of positivity for S-100, as well as a very high Ki-67 index. The tumor cells were negative for desmin, Myogenin, and pankeratin.
MPNST is the preferred terminology for lesions previously designated as malignant schwannoma, neurogenic sarcoma or neurofibrosarcoma. Although these lesions occur most often in adults, they have been described in children, as in this case. They fall under the WHO category of Grade III or IV, and often have geographic necrosis, and mitotic activity exceeding 4 mitotic figures per high power field. Approximately ½ of MPNSTs arise in patients with NF-1, with 2/3 of these arising in association with or from a neurofibroma. MPNST variants, including glandular and the so-called Triton tumor (MPNST with rhabdomysarcoma-like elements), are more often associated with NF-1 and have a poorer prognosis. The overall 5- and 10-year survival rates for MPNST are 34% and 23%, respectively.
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