Adenodermatofibroma possessing dilated glandular structures with eccrine features: A case study

Adenodermatofibroma is a newly recognized variant of dermatofibroma characterized by dense proliferation of fibroblasts and histiocytes admixed with dilated glandular structures showing apocrine secretion. Only five cases of adenodermatofibroma have been reported to date. We report an additional case of adenodermatofibroma on the back of a 67-year-old female. In addition to the dilated glandular structures, nondilated eccrine units were present at the upper periphery of the lesion, above which the normal eccrine glands reside. Although decapitation secretion was observed in the nondilated eccrine units at the upper periphery of the lesion, this was not observed in the dilated glandular structures. The inner cells of the dilated glandular structures were S-100 positive, similar to those of the secretory portion of eccrine glands. We considered the glandular structures in our patient were derived from the entrapped eccrine units. We suggest that the term "apocrine metaplasia" be applied to eccrine units showing decapitation secretion.