1. ASNR 2015 Psammomatous Melanotic Schwannoma of The Spine: A Rare Case Report S Bakan, Y Kayadibi, E Ure, M Asik, Z I Hasiloglu Istanbul University Cerrahpasa Medical Faculty, Istanbul, Turkey Presentation number:EP-149 Submission number:1512

2. Disclosure No Disclosures

3. Background Melanotic schwannoma is an intermediate tumor between schwannoma and malign melanoma which are both originates from neuroectodermal tissues. These tumors are usually in benign nature but in literature malignant degeneration, recurrence and metastasis had been reported in 26%-38.9% of the cases.

4. Purpose Our purpose in this case report to discuss the imaging findings of a rarely seen psammomatous type of melanotic schwannoma.

5. Materials & Methods A 31-year-old woman admitted to our department with back pain. Magnetic resonance (MR) Imaging and computed tomography (CT) were performed for diagnosis.

6. Results MR Imaging revealed a paravertebral, extrapleural soft tissue mass measuring about 2,5 cm that was originating from spinal canal and extending into neural foramen at the level of T4 - T5. The mass was containing focal hyperintensity on T1- weighted images and containing a cystic component. The lesion was enhancing homogeneously.

7. Results CT showed punctate calcifications inside of this soft tissue lesion. Positron emission tomography (PET)/ CT scan revealed an increased FDG. Patient underwent surgery and pathological examination revealed spindle- shaped Schwann cells and melanin pigmented cells which were diagnostic for psammomatous type of melanotic schwannoma.

8. MR Imaging and PET/CT imaging Findings MR imaging showed a paravertebral, extrapleural soft tissue mass that was originating from spinal canal and extending into neural foramen at the level of T4 - T5. The lesion was hyperintense on T1WI. PET/CT scan revealed an increased FDG.

9. Discussion There are two subtypes of melanotic schwannoma including psammomatous type and sporadic type. Psammomatous type of schwannomas coexists within Carney complex (CC) in 50% of cases, so patient should be investigated with further examinations in terms of CC.

10. Discussion Our patient had no clinical and physical findings that was supported CC. Melanin containing lesions that including malignant melanoma, melanositoma, pigmented neurofibroma, paraganglioma, leptomeningeal melanosis, hemorrhagic metastatic lesions due to breast cancer, thyroid cancer, choriocarcinoma and lung cancer must be considered in differential diagnosis which are other reasons of T1 shortening.

11. Conclusion In this presentation, we presented a rare case of psammomatous melanotic schwannoma of the spine with its radiological features. In fact, there is no characteristic clinical or imaging finding and PET/CT has limited value in differential diagnosis. The exact diagnosis could only confirmed by surgery and immunohystopathological examination.

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