Contributed by Marco Gessi1, Martina Messing-Jünger2, Andreas Röhrig2, Gerrit H. Gielen1, Torsten Pietsch1, Frank K.H. van Landeghem1
1 Institute of Neuropathology, University of Bonn Medical Center, Bonn, Germany;
2 Department of Neurosurgery, Asklepios Kinderklinik, St. Augustin, Germany
After an uncomplicated pregnancy and birth an otherwise healthy girl showed a skin appendix in the dorsal mid-cervical region. The lesion was notable in prenatal routine ultrasound examination at the 19th gestational week (Fig. 1A, arrow). Family history was negative for neurodevelopmental pathologies. A primary ultrasound examination revealed a connection with the cervical spinal cord. The consecutive MRI of the neuroaxis confirmed a dorsal connection of the skin malformation with a dysplastic cord in the related segments (Fig. 1 B, arrow). The brain scans demonstrated multiple subependymal heterotopias. EEG was without epileptogenic focus. Clinically no epileptic seizures occurred so far. EEG was did not show epileptogenic foci. After a follow up of 18 months a significant motor developmental delay was noticed. Speech development was above average. At the age of 2 months the little girl underwent plastic surgery of a dysraphic malformation of the cervical cord with resection of a skin appendix (Fig. 1C) and removal of tethering structures at the dysplastic cervical cord at level C6. Dura mater and skin were closed without complication. The postoperative course was uneventful. No signs of re-tethering were found in long-term follow up.
Grossly, the material consisted of small fragments of adipose and fibrous tissue, partially covered by skin. The microscopic examination revealed fibro-adipose tissue containing numerous nerve fascicles with degenerative features (Fig. 2, arrows). Along the nerve fascicles, a 0.7 cm large nodule-like lesion composed by "onions bulbs"-like structures with up to 10 concentric lamellae and one or more centrally placed axons (Figs. 3, 4, 5; Fig. 3 Masson-Trichrome stain) were present. The cells surrounding the axons appeared focally densely packed (Fig. 6). The axons were labelled with neurofilament antibody (NFP) (Fig. 7) and surrounded, also in more cellular areas, by S-100 (Fig. 8) as well as GLUT-1 positive Schwann cells. EMA staining was present only in the outer layer of "onion bulbs" (Fig. 9). The proliferation index evaluated with MIB-1 antibody reached a value up to 1%, restricted to few lymphocytes. The nerve fascicles were embedded within fibrotic meningeal tissue.