In a provisionally-published paper by Almarestani, Longo, and Ribeiro-da-Silva, chronic inflammation was shown to induce the growth of sympathetic nervous system fibers in the dermis. The researchers injected complete Freund's adjuvant into the paws of rats and subsequently stained tissues after several weeks. Nerves were shown to change typical innervation of the lower dermis to innervation of the upper dermis as well.
Of course, nerve fibers don't really correspond to the fibers present in Morgellons as the images in the PDF demonstrate. My best guess is that Morgellons represents a few legitimate unrelated cases of pathology of unknown origin combined with a lot of DP and FII. It would be interesting, though, to discover a real pathological process at work in Morgellons.
- Lina Almarestani, Geraldine Longo, Alfredo Ribeiro-da-Silva (2008). Autonomic fiber sprouting in the skin in chronic inflammation Molecular Pain, 4 (1) DOI: 10.1186/1744-8069-4-56