Gottron Papules Show Histopathologic Features of Localized Lymphedema.

Although Gottron papules are a relevant feature of dermatomyositis, they are reported in very few papers in the literature, and the largest series on the subject includes 11 cases. We intend to study the main histopathologic features of Gottron papules in a series of 12 biopsies. We evaluated hematoxylin-eosin stains on all cases. We also performed histochemical stains to evaluate the dermal deposition of mucin. Finally, we studied the CD123 cell population in the inflammatory infiltrate by immunohistochemistry. We found that the epidermis was either acanthotic or hyperplastic in all cases. We found a dermal inflammatory infiltrate in all cases but one. Mucin deposition in the reticular dermis was an inconstant feature. Vacuolization of the basal layer was also a frequent finding. There was thickening of the base membrane on periodic acid-Schiff stains in all our cases. We identified CD123 cells in all cases but 2. Intraepidermal CD123 cells were also found in 8 cases. All cases but one showed lymphangiectasia in the upper part of the dermis, including the papillary and reticular dermis. In addition, collapsed lymphatics were evident underlying the dermal sclerosis. We conclude that Gottron papules show typical features of localized lymphedema.