Uncommon Patterns and Clinical Features of Peripheral Nerve Sheath Tumors of the Spinal Cord: UCSF Experience 1983-2010.
Agne Naujokas, Peter Modera, Philip Weinstein, Tarik Tihan. University of California – San Francisco
Background: Peripheral nerve sheath tumors (PNSTs) are one of the most common primary neoplasms in the spinal cord and the overwhelming majority is benign. While complete resection is the goal, incomplete resection may be required to preserve function. The challenges in the management of the PNSTs are often related to their long natural history and the unusual patterns that do not exactly fit the prototypes. Such unusual patterns may often cause uncertainty about the diagnosis.
Design: In order to determine the frequency and relevance of uncommon patterns seen in spinal cord PNSTs, we reviewed the Department of Pathology archives during a 27-year period (1983-2010). Patients without available pathology material or sufficient information were excluded. Histopathological features of tumors were recorded and were correlated with tumor clinical findings in order to determine their association with outcome parameters.
Results: Among a total of 352 patients with primary spinal cord neoplasms, 178 (51%) had PNSTs (109 male/69 female; median age: 47.7; range: 1-89). There were 140 schwannomas (87% classic type, 6% myxoid, 4% cellular, 2% hyalinizing, and 1% melanotic), and 38 neurofibromas (26 patients with NF1 and 1 with NF2). Trapped ganglion cells were seen in 56% of neurofibromas and only 2% of schwannomas. Degenerative changes and pleomorphic nuclei were present in 14% and 24% of schwannomas, respectively. Uncommon findings in schwannomas included necrosis (4% of cases), pseudoglandular formation (3%), epithelioid differentiation (2%), and focal infiltrative pattern (1%). Chronic inflammatory infiltrates other than macrophages were seen in 20% of schwannomas and only 4% of neurofibromas. There was no significant correlation between recurrence and extent of resection (p=0.2519) or location (p=0.0529) in schwannomas. Aggressive clinical course was seen in 2 of 5 cellular and both melanotic schwannomas. Myxoid and hyalinized types had a significantly more indolent course.
Conclusions: Necrosis, trapped ganglion cells and epithelioid features are rare features that may cause challenges in the diagnosis but do not seem to influence biological behavior. Cellular and melanotic Schwannomas are among those with more aggressive course. Extensively hyalinized or myxoid Schwannomas have excellent prognoses even in the face of subtotal resection. Some subtotally resected Schwannomas may not require additional treatment.
Tuesday, March 1, 2011 1:00 PM
Poster Session IV # 239, Tuesday Afternoon