case_images: PMC11165122_01
case_images: Magnetic resonance imaging (MRI). (A-C) An intramedullary tumor was located at C6-T4 with mixture of iso- and hypointensity on sagittal T1-weighted image (T1WI) (A), non-homogeneous hypointensity on sagittal T2-weighted image (T2WI) (B), and slightly non-homogeneous enhancement on sagittal T1WI with gadolinium (C). (D, E) Long T1 [(D), sagittal] and long T2 [(E), sagittal] signals with increased signal intensity of fat-suppressed images [(F), sagittal] at the level between medulla and C6 suggestive of syringomyelia at the proximal end of the lesion.
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case_images: Magnetic resonance imaging (MRI) of the spine revealed a mixture of iso- and hypointense intramedullary mass at the C6-T4 level on T1-weighted images and non-homogeneous hypointensity on T2-weighted images ( Figures 1A, B ). After administration of contrast material, slightly non-homogeneous enhancement of the focal lesion at the T2-T3 level was observed ( Figure 1C ). T1 and long T2 signals with the increased signal intensity of fat-suppressed images at the level between the medulla and C6 indicated syringomyelia at the proximal end of the lesion ( Figures 1D-F ). The appearance of the lesion on MRI was misdiagnosed as ependymoma initially in this case.
case_images: Intraoperative photograph showing the darkly pigmented intramedullary lesion with multiple small satellite lesions under the pia (A). After spinal cord incision, the coal cinder-like lesions were removed in piecemeal, and multiple biopsies were taken (B, C).
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case_images: At the dural opening, a black tumor with multiple small satellite lesions under the pia was observed, and the main tumor was found to be apparently infiltrated with the parenchyma ( Figure 2A ). After the spinal cord incision, the coal cinder-like lesions were removed in piecemeal, and multiple biopsies were taken ( Figures 2B, C ).
case_images: Neoplasm was densely cellular arranged in nests and sheets with deposition of abundant melanin pigment [(A); hematoxylin and eosin (H&E), magnification x100]; pleomorphic ovoid, spindle, or polygonal cells with significant nuclear atypia characterized by large nuclei, high nuclear-to-cytoplasmic ratio, and scattered mitosis [(B); H&E, magnification x200]; representative necrosis in the tumor [(C); H&E, magnification x200]; tumor cells with granular cytoplasmic pigmentation were arranged around the vascellum [(D); H&E, magnification x200]; positive staining for HMB-45, S-100, and MelanA [(E-G); magnification x200]; Ki-67 labeling indices counted more than 50% denoted pigmented cells that were mitotically active [(H); magnification x200].
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case_images: Microscopic examination revealed that the tumor consisted of an abundance of ovoid, spindle, or polygonal tumor cells and was arranged in nests and sheets accompanying the deposition of abundant melanin granules ( Figure 3A ). Higher magnification of the lesions showed significant cellular pleomorphism with nuclear atypia and enlargement and a high nuclear-to-cytoplasmic ratio ( Figure 3B ). Necrotic areas were also seen, but no evidence of hemorrhage or products of its degeneration was identified, and tumor cells with granular cytoplasmic pigmentation were arranged around the vascellum ( Figures 3C, D ). Immunohistochemical examination showed that the neoplastic cells stained strongly positive for antimelanoma antibody (HMB-45), S-100, and MelanA, and Ki-67 staining showed high proliferative index (50%), both pointing to malignant melanoma of the spinal cord ( Figures 3E-H ).