Peer-review started: November 1, 2015
First decision: November 30, 2015
Revised: December 19, 2015
Accepted: January 27, 2016
Article in press: January 29, 2016
Published online: May 2, 2016
Processing time: 180 Days and 17.5 Hours
Dermal mucinosis is often associated with collagen diseases such as rheumatoid arthritis, lupus erythematosus, and dermatomyositis, in addition to autoimmune thyroiditis. We report eight cases of dermal mucin deposition secondary to typical dermatomyositis with cutaneous lesions known as heliotrope rash and Gottron’s papules. Striking mucin deposition was observed in both the papillary dermis and reticular dermis of all biopsy specimens. Immunohistochemical analysis showed that CD34+ dermal dendritic cells (DDCs) in the perilesional area in combination with vimentin+ cells within the mucinous lesion might be important in giving rise to abnormal deposition of dermal mucin. On the other hand, numbers of factor XIIIa+ DDCs and tryptase+ mast cells were reduced within and surrounding the mucin deposition, as compared with those in the dermis of normal controls. A pathogenic mechanism of dermal mucin deposition is proposed.
Core tip: Immunohistochemical analysis of skin biopsy specimens with dermatomyositis showed the involvement of CD34+ dermal dendritic cells, α-smooth muscle actin+ myofibroblasts and possibly mast cells, as well as vimentin+ fibroblasts for abnormally dermal mucin production. Further pathophysiological studies are required to more precisely clarify secondary cutaneous mucin deposition by CD34+ dermal dendritic cells. CD34+ dermal dendritic cells and mast cells might be important in giving rise to deposition of dermal mucin in dermatomyositis.