PMC4921164_01
The sagittal T1- (A) and T2-weighted (B) images and the postcontrast sagittal (C) and axial (D) fat-suppressed T1-weighted images clearly show the intramedullary, paracentral right located, expansive melanocytoma at the C2 / C3 level with homogeneous contrast enhancement. Additionally, a T2w hyperintense (B) per focal tumoral edema was noticed, suggestive of myelopathy.
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Intraoperative view of the spinal cord after opening the dura mater via dorsal laminectomy; the tumor shines brightly in (A). Melanocytoma with visible caudal tumor edge (B) and partially dissected melanocytoma (C).
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Through a small tumor nodule protruding between the right dorsal nerves C2 and C3, the pia mater was prepared to enable access to the intramedullary tumor mass (Figs. 2, A-C).
Histological examination revealed a melanocytic neoplasm with moderate mitotic activity and infiltrative growth pattern. Conventional hematoxilin and eosin staining (A; x100) shows lack of substantial cytologic atypia; a mitotic figure is depicted in the inset. Moderate MIB1 staining supports higher proliferative potential (B; x400). Melanocytic differentiation is disclosed by melanin pigmentation (C; Fontana-Masson staining, x400), and immunohistochemical positivity for the melanocytic markers HMB45 (D; x400) and Melan A (E; x200). Staining for glial fibrillary acidic protein (F; GFAP, x100) highlights the invasive tumor growth pattern, with unstained tumor cells and positively stained infiltrated central nervous tissue.
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Histopathological examination revealed a spindle-cell neoplasm with melanin pigmentation, moderate mitotic activity (4 mitoses/10 high-power fields; MIB1 overall 5%, focally up to 8%), positivity for melanocytic markers by immunohistochemistry (S100 protein, Melan A, HMB-45), and infiltrative growth pattern (Figs. 3A-F).
The followup MRI after 3 months indicates the solid enhancing tumor recurrence (B) at the right adherent lateral resection border at the C2 (C) and C3 level (D). The signs of cervical myelopathy were still recognizable on the sagittal T2-weighted (A) images.
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The first followup MRI revealed a solid enhancing tumor nodule at the right adherent lateral resection border (4 x 7 x 13 mm) following the same signal characteristics as the primary melanocytoma, in keeping with tumor recurrence (Figs. 4A-D).