1. Has there been any recent trauma to that area?
2. The most likely diagnosis is periungual fibrokeratoma.
3. Other conditions one may consider in the differential include: cutaneous horn, wart, rudimentary supernumerary digit, Koenen tumor and superficial acral fibromyxoma.
4. The condition is benign. It often emerges beneath the proximal nail fold with a narrow base and a hyperkeratotic tip, and can cause nail plate grooves.
5. Surgical excision is curative. Damage to the matrix is a potential complication.
When A Patient Has An Unusual Growth On A Toe
Acrochordons. An acrochordon is one of the most common benign skin tumors. These lesions are commonly known as skin tags and occasionally fibroepithelial polyps. They often develop in areas of skin friction, which certainly takes place at the tip of the toe. However, these lesions are usually much smaller and not nodule-like. While these lesions are benign, they may be associated with other disease states, occasionally warranting closer examination of the patient for other signs and symptoms.
Rudimentary supernumerary digits. Such digits can clinically appear as miniature accessory digits much like a periungual fibrokeratoma. However, rudimentary supernumerary digits are usually present since birth and are bilateral. In this patient’s case, the growth formed over the past two years. The histological image of these entities is similar with an increase of keratin at the distal edge of the specimen, which can look similar to a nail.
Cutaneous horn. A cutaneous horn usually occurs in sun-exposed areas, particularly the face, nose, forearms and dorsal hands. It is a hyperkeratotic papule with the height greater than one-half the width of the base. Usually a cutaneous horn is several millimeters long. In this patient’s case, the growth was much larger.
Superficial acral fibromyxoma is a rare soft tissue tumor with a predilection for the nail region of the fingers and toes.12 The neoplasm occurs in adults as a solitary, slow-growing mesenchymal mass involving the periungual and subungual areas of the fingers and toes. A histological diagnosis is needed to differentiate this from a periungual fibrokeratoma.
The biopsy initially ruled the growth as a connective tissue nevus, which means nothing more than a localized malformation of dermal collagen. They are uncommon skin lesions that occur when the deeper layers of the skin do not develop correctly. Based on the clinical picture of this patient, I had some reservation about the diagnosis.
If the pathology reading does not make sense to you, it is your obligation to speak with the pathologist or you may send the slides to another pathologist. This is a common practice. I spoke with the pathologist and met with him in person to go over the case, and show him a photo of the growth in question. After the discussion, he modified his diagnosis to acquired periungual digitial fibrokeratoma. It is very important to provide supporting clinical information to the dermatopathologist in addition to the biopsy specimen.
Dr. Morse is the President of the American Society of Podiatric Dermatology. He is a Fellow of the American College of Foot and Ankle Surgery and the American College of Foot Ankle Orthopedics and Medicine. Dr. Morse is board certified in foot surgery.