Fig. 1

Clinicopathologic features of the patient. Photograph of the congenital cutaneous nevus (a). Preoperative brain MR images (b, c). Histology of the nevus (d). Spinal cord MR image obtained at emergent admission for quadriplegia (e). Body CT image at respiratory failure (f). Brain MR image 10 days before death (g). Photographs of the brain (h), spinal cord (i), and abdomen (l) at autopsy. Photographs of cut sections of the brain (j) and spinal cord (k) after formalin fixation. Histology of the kidney (m)

Photograph of a large melanocytic nevus on the patient’s left flank to back (a). Post-contrast MR images showed hydrocephalus (b) and linear contrast-enhanced lesion along the sulcus at the right parietal lobe (c). A small number of melanocytes were scattered in the dermal layer (d). Post-contrast MR image revealed extensive spinal dissemination (e). Body CT showed massive ascites and compression of the lungs due to elevation of the diaphragm (f). Post-contrast MR image showed an enlarged linear contrast-enhanced lesion along the brain surface and an intraparenchymal mass lesion on the corpus callosum, but no signs of cerebral herniation (g). At autopsy, macroscopic examination of the whole brain and spinal cord revealed a thickened and black leptomeninges (h, i) and multiple masses of tumor cells on the surface of abdominal organs (l). Tumor cells invaded the brain parenchyma adjacent to the Sylvian fissure (j) and covered the whole circumference of the spinal cord (k). The tumor cells were observed on the surface of the kidney but did not infiltrate the renal medulla due to Gerota’s fascia (m). Scale bars: 100 μm