Abstract

Background: Numerous histologic variants of dermatofibroma (DF) have been described; however, the histogenesis of this entity remains elusive. Anecdotal evidence suggests an association between hypocellular DFs and patient age due to age-related biological evolution. Methods: We analyzed 392 DFs diagnosed at an academic dermatopathology laboratory between January 2019 and September 2020. Two blinded board-certified dermatopathologists independently examined all specimens and assigned a histologic type (conventional, hypocellular, cellular, hemosiderotic/aneurysmal, lipidized, indeterminate, or other.) Specimens with concordant histologic classification were included in the study. Patient demographic information and specimen information were collected, and statistical analysis was performed with the aid of a biostatistician. Most specimens (306 of 392, 78%) had a concordant histologic type and were included in the analysis. Results: Most of these specimens (84%, n=256) were in patients between the ages of 30 and 69 years. The most frequent variant was conventional (70%, n=214,) followed by hypocellular (24%, n=73,) cellular (3%, n=9,) hemosiderotic/aneurysmal (2%, n=7,) and indeterminate (1%, n=3.) The frequency of hypocellular DFs increased as a function of patient age, with a strong positive linear correlation (R-squared=0.82, p=0.002.) Other variants did not demonstrate a statistically significant association with patient age. Conclusions: This is the first study to quantifying the frequency of DF histologic variants stratified by patient age and substantiates the notion that DFs become increasingly hypocellular with increasing patient age. A limitation of this study is the inclusion of superficial biopsies, which preclude assessment of deep dermal histologic features, and may lead to an underestimate of some variants, such as cellular DFs, in superficial specimens. The biological mechanisms involved in this progression remain an area of interest.

Financial Disclosure:
No current or relevant financial relationships exist.