PMC5956056_01
a Preoperative MRI T1WI with contrast. b Intraoperative view with the lesion under the nerve roots. c During tumor removal. d Postoperative MRI T1WI with contrast
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Fig1
T11 to L4 averaging 9 cm in long axis. The lesion was hyperintense on T1 with isointense signal at the cephalad end; in T2, it was hypointense and it showed intense homogenous contrast enhancement. There was a small syrinx proximal to the lesion, with no peritumoral edema (Fig. 1a). At this point, a brownish black space-occupying lesion was seen among the roots attached to the ventral dura (Fig. 1b). The lesion was adherent but dissectible from cauda equina roots (Fig. 1c). Tesla MRI scanner Intera, Philips Medical systems, Best, Netherlands), which showed the small residual left at the conus medullaris (Fig. 1d).
Images a (x 40) and b (x 100) are hematoxylin and eosin-stained slides showing tumor formed of epithelioid and spindle cells mostly masked by dense brown pigment deposition. Immunohistochemistry: negative for epithelial membrane antigen (EMA) (c). Less than 1% of tumor cells are stained for Ki67 (d). Tumor cells are focally positive for S100 (e)
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Fig2
Microscopic picture using hematoxylin and eosin stains revealed hypo- to moderately cellular tumor composed of spindle cells with bland oval nuclei with some macrophages and dense cytoplasmic brown melanin pigments, with no significant mitoses or nuclear atypia (Fig. 2a x 40, Fig. 2b x 100). Immunohistochemistry: negative for epithelial membrane antigen (EMA) (Fig. 2c). Less than 1% of tumor cells are stained for Ki67 (Fig. 2d). Tumor cells are focally positive for S100 (Fig. 2e).