PMC9805607_01
Cutaneous pigmentation (white arrows) of the periorbital and malar region on the unilateral left side of the face head in a nondermatomal fashion.
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F1
The giant nevus was distributed unilaterally across the left side of the patient's face and head in a nondermatomal fashion [Figure 1].
Preoperative multiplanar and multisequential MRI of the brain. (a) T1 without contrast shows a heterogeneous hyperintense lesion in the left temporal region, (b) T1 with contrast shows further enhancement on contrast administration, (c) T2 shows a hypointense lesion with surrounding hyperintense signals, (d) fluid-attenuated inversion recovery showing edema surrounding lesion, (e) T1 post contrast sagittal, and (f) susceptibility weighted image displaying areas of signal drop out.
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F2
Subsequently, brain magnetic resonance imaging (MRI) showed a left temporal lesion in close approximation to the greater wing and petrous portion of the sphenoid bone and measured approximately 37 x 41 x 32 mm [Figure 2].
Surgical images of densely pigmented leptomeninges of the brain, as seen under the operating microscope. (a and b) Pattern of black multiple discrete clusters of hyper-pigmentation seen over the brain meninges (white arrow). (c) Extensive pigmentation seen as a sheet of dots spread over the leptomeninges (white arrows). (d) Dark, blotched, and pigmented vascularized (white arrows) meninges.
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F3
During the procedure, patchy pigmented leptomeninges, islands of pial pigmentation, and perivascular dark arachnoid deposits were also noticed [Figure 3].
Histopathology of primary leptomeningeal melanoma. (a) Hematoxylin and Eosin stained sections show sheets of medium-sized polygonal cells with moderately pleomorphic nuclei (white arrows) containing dispersed chromatin, macronucleoli, and moderate amounts of eosinophilic cytoplasm. (b) Immunoperoxidase staining for Melan A shows diffuse cytoplasmic staining (white arrows) in tumor cells. (c) Positive staining for Ki-67 (white arrows) is observed.
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F4
Immunohistochemical stains were performed which showed a reactivity pattern consistent with melanoma; Melan A Positive, HMB45 Positive with Ki-67 high proliferative index [Figure 4].