Background: Multiple dermatofibromas (DFs) have been reported to develop in various disorders, especially in systemic lupus erythematosus (SLE).
Objective: To investigate the role of mast cells in the formation of multiple DFs in association with autoimmune disorders, we quantified the number of mast cells.
Methods: Three cases who developed multiple DFs with positive antinuclear antibodies are described; a 54-year-old woman with a 10-year history of SLE with 13 lesions, a 33-year-old woman with 11 lesions and a 46-year-old woman with SLE and Sjögren syndrome with 10 nodules. Distribution and number of mast cells were examined in the removed lesions of DFs.
Results: In 2 cases, mast cells in the upper portion of the lesions were increased in number in comparison with the solitary DF, nevocellular nevus and normal skin. These 2 cases had early DFs from the onset; in the remaining case in which mast cell number was not increased, they were old or fading lesions.
Conclusion: It is suggested that mast cells may play a role in induction and exacerbation of the fibrotic process of multiple DFs, and they are supposed to be a reactive hyperplasia in association with systemic autoimmune disorders.