A rare case of bilateral symmetrical broad‐based acquired ungual fibrokeratomas

Acquired ungual (acral) fibrokeratoma (AUFK) is an unusual fibroepithelial tumour. It can present as a branching, dome, rod or verrucous growth emanating from the proximal nail fold (periungual), from under the nail plate (subungual) or through the nail plate (transungual).1 Trauma precedes tumour growth in approximately 10% of published cases.1 Other hypotheses include overproduction of Factor XIIIa or a genetic basis.1-3 A case of bilateral symmetrical AUFK has only been described once.4 We present a striking case of bilateral symmetrical broad-based AUFK with complete involvement of the proximal nail fold. A 21-year-old female had a 3-year history of asymptomatic broad tumours of the bilateral great toes, with a hyperkeratotic distal edge and longitudinal ridging of the nail plate (Figure 1). The excisions were staged sequentially. After achieving a digital block, a tourniquet was applied and the time of application was noted. Two incisions were placed on the lateral aspects of the proximal nail fold, which was reflected to expose the base of the tumour (Figure 2a). Blunt mobilization and tangential scalpel dissection of the base was performed to avoid damage to the nail matrix (Figure 2b–d). Incision lines were sutured and dressings were placed. The tourniquet was removed and time of removal was noted. Histologically, the tumour showed a polypoid lesion with thickened squamous epithelium and hyperkeratosis (Figure 3). There was a fibrovascular core containing well-collagenized stroma including vertical streaking of collagen and sparse, bland spindled cells (Figure 3b), all consistent with AUFK. AUFK can show similar histology to Koenen tumours arising in patients with tuberous sclerosis complex (TSC). The distinction with TSC is made on clinical grounds by examination for other cutaneous features of TSC,2 which were absent in our case. Periungual digital fibrokeratomas which are not attached the nail unit can be excised as an ellipse parallel to the direction of the lateral nail fold.5 Most fibrokeratomas are small and based in the lateral grooves.1, 5 Two lateral incisions in the skin overlying the tumour are made to expose the most proximal part of the tumour and elevator or fine point scissors will gently detach the tumour from the periosteum.5 Rarely, subungual fibrokeratomas can arise from the nail bed which require partial nail avulsion.5 Depending on its size, subungual tumours can either be elevated from the nail bed or excised as an ellipse above the level of the periosteum. Intraungual fibrokeratomas occur in the nail matrix and can form a canal. Accessing the tumour either from this canal or through partial nail avulsion can facilitate removal. Our case was unique in its broad-based and superficial tumour origin which required the entire proximal nail fold to be reflected. The tumours were not adherent to the periosteum which facilitated removal with minimal trauma to the nail using blunt mobilization and tangential sharp dissection with a scalpel blade. At follow-up 5 months after excision of the left-sided tumour and 1 month after the right side, the patient had achieved an excellent result with some persisting longitudinal ridging (Figure 4). Dr. Ankit Gupta reviewed the literature and contributed to the principal manuscript drafting. Dr. Sara Lee de Menezes and Dr. Nicholas Manuelpillai reviewed the literature, contributed to manuscript amending and assisted with the collection of patient data. Dr. Saurabh Prakash interpreted the histological findings and contributed to manuscript amending. Prof Johannes Steffen Kern had responsibility for conception of the report, patient data collection, analysis and interpretation, contributed to manuscript drafting and critical revision of the article. All authors issued final approval for the version to be submitted. Prof Johannes S Kern is an Editorial Board member of Australasian Journal of Dermatology and a co-author of this article. To minimize bias, they were excluded from all editorial decision-making related to the acceptance of this article for publication. Dr. Saurabh Prakash has reviewed manuscripts for the AJD on a voluntary basis. Written informed consent was obtained from the individual included in the case. The data that support the findings of this study are available from the corresponding author upon reasonable request.