In 1989, Stu Salasche, Bill Grabski, Martha McCollough and Vince Angeloni described an entity they described as being either enveloped in the frontalis muscle of the forehead, or just beneath it. Their term, Frontalis-Associated Lipoma, has stuck with this entity ever since.
The tricky thing about FAL is they are not easily removed, and in fact are a real pain in the neck because of the investiture in the frontalis. My preferred technique, which involves a horizontal incision following the rhytids, followed by significant undermining and then a vertical incision in the frontalis, following the muscle fibers, down to the lipoma, is by far the best way to handle them. I learned that technique from the authors themselves, while they were on faculty at our sister residency at Brooke Army Medical Center in San Antonio.
The clues that we were not dealing with an epidermal inclusion cyst are primarily that the lipomas are soft and much more mobile than a cyst of that size.