Contributed by Diana Thomas, MD, PhD and Clayton Wiley, MD, PhD
A woman approximately 50 years of age with type I diabetes mellitus with end-organ damage (peripheral neuropathy and nephropathy status post renal transplant), peripheral vascular disease and hypothyroidism presented with progressively worsening left-sided numbness, weakness and leg pain for the past 2 to 3 months. Additionally over the past week, her right leg had become numb from the knee down. Around the same time, her left hand also became weak. She denied symptoms in the right arm and any spine pain. Physical exam revealed decreased strength in the left upper and lower extremities and decreased sensation in the lower extremities.
IMAGING STUDIES AND INTRAOPERATIVE FINDINGS
MRI of the cervical, thoracic and lumbar spine was performed without contrast. T2-weighted images (Figure 1) showed an irregular hyperintense signal on the left lateral spinal cord and within the left neural foramina at the C6-C7 level.
The patient underwent surgical excision of the mass and C4-T2 laminectomy the following day. Intraoperatively, the tumor was found to be intradural and extramedullary, with erosion of the bone around the left C6-C7 foramen. An intraoperative consultation was requested and the intraoperative diagnosis was neural tumor, possible schwannoma (Smear).
The pathology specimen consisted of multiple fragments of red-tan soft tissue measuring 3.5 x 3.0 x 0.3 cm in aggregate.
Microscopic examination of the tumor showed sheets of large, oval to slightly spindled cells with abundant granular cytoplasm, round to oval nuclei, vesicular chromatin, and prominent nucleoli (Figures 2, 3, H&E permanent). Some of the tumor cells contained intracellular pigment (Figure 4). Numerous macrophages present in the tumor also contained numerous pigmented granules. Immunohistochemical stains for HMB45, vimentin, S100 and Melan A (Figure 5, MelanA) were positive in the tumor cells. The tumor cells were negative for AE1/AE3, EMA, Cam5.2, GFAP, p53 and BRAF. The Ki-67 proliferation index was less than 1% (Figure 6, Ki67).