In 1968, Bart et al
described 10 cases of an uncommon acquired growth that was located on the fingers. Although it clinically resembled a cutaneous horn or rudimentary supernumerary digit, it had distinct histopathological findings. The authors named this growth acquired digital fibrokeratoma (ADFK). Subsequently, Pinkus
reported 28 more cases; however, these lesions occurred not only on the fingers, but also on the proximal hand, toes,
sole, and one in the prepatellar region. For this reason, Verallo et al suggested the entity might more appropriately be called an acral fibrokeratoma.
Similar growths have been reported to occur in the subungual or periungual region of patients with tuberous sclerosis, and they are referred to as Koenen tumors or garlic clove fibromas. They differ, however, in that they tend to be multilobulated and involve several digits and, histologically, may have atypical stellate myofibroblasts.