| Contributed by Koushan Siami-Namini MD1, Rhonda Shuey-Drake MS1, Don Wilson MD2,
Paul Francel MD3, Arie Perry MD4, Kar-Ming Fung MD, PhD1
| 1Department of Pathology, 2 Department of Radiology, 3 Department of Neurosurgery
University of Oklahoma Health Science Center, Oklahoma City, OK
4 Division of Neuropathology, Washington University, St. Louis, MO
|Published on line in March 2005|
A 15 year-old female presented to the Emergency Room with urinary retention and inability to walk. She had developed progressive low back pain and bilateral leg pain about 2 months prior to presentation. Physical examination demonstrated bilateral positive Babinski reflex, bilateral positive Hoffmann's reflex, positive Romberg reflex and positive bulbocavernous reflex. Sagittal T1 weighted MRI scan post Gadolinium (Gd) using fat saturation technique showed an intensely enhancing intraspinal, extradural, 6.5 X 0.8 X 2.3 cm (cranial-caudal, anterior-posterior, transverse) mass, with anterior displacement and compression of the spinal cord (Figure 1A). The mass extended from T3 to T7. Axial T1 weighted MRI scan post Gd at T5 showed bilateral transverse process and spinous process involvement (Figure 1B). Axial T1 weighted MRI scan after Gd showed enhancing tumor in the spinal canal and neural foramina from T4 to T7 (Figure 1C, scan was taken at T5). A decompression surgery was performed.
The surgery yielded a 3.5 X 3.0 X 0.8 aggregate of tan soft tissue fragments. Intraoperative cytologic preparation (squashed preparation) revealed a rather monotonous population of small blue cells with round, centrally located hyperchromatic nuclei; the cytoplasmic membrane was distinct; the cytoplasm was granular (Figure 2A) and contained small cytoplasmic vacuoles (Figure 2A, arrows). These vacuoles were best visualized with DiffQuick stain (Figure 2A, insert). The cytoplasmic vacuoles could not be well appreciated on frozen sections.
Formalin fixed, paraffin embedded sections showed tumor invasion into bone and fibroadipose tissue (Figure 2B). The neoplastic cells were small to medium sized and had mild variation in nuclear size with the smaller ones hyperchromatic to the larger ones. Mitotic figures were common. The cytoplasm was delicate to granular and had small cytoplasmic vacuoles (Figure 2C) that contained substantial amount of periodic acid Schiff (PAS) positive (Figure 2C, insert) diastase sensitive material. The tumor cells demonstrated strongly positive membranous immunoreactivity for CD99 (Figure 2D) but no immunoreactivity for S-100 protein, HMB45 and leukocyte common antigen.
Fluorescent in situ hybridization (FISH) demonstrated fusion signals consistent with reciprocal translocation of t(11;22)(q24;q12) (Figure 2D, inset). The cytoplasmic vacuoles were well demonstrated in resin embedded section (Figure 3, insert). Ultrastructurally, the tumor cells had sparse, inconspicuous cytoplasmic organelles and prominent non-membrane bound cytoplasmic vacuoles that were devoid of cytoplasmic organelles (Figure 3A). Some of these vacuoles contained residual glycogen particles (Figure 3B).