In this study, the technique on mimical reconstruction and aesthetic repair of the nail following resection of subungual melanocytic nevus is a reliable and feasible, all patients obtained a satisfactory appearance.
Although melanocytes are the normal pigment-producing cells in the skin [1], the density of melanocytes in the nail matrix (200/mm2) and nail bed (absent to 50/mm2) is much smaller than in normal skin (1150/mm2) [3, 5]. These also explains why some of subungual melanocytic nevi tend to be not black. Therefore, it is not reliable to evaluate the malignant degree of pigmented lesions through the color alone.
However, the thickness of the normal nail bed in healthy individuals was approximately 1.17 mm [18]. Histopathologically, melanocytes in nail matrix were usually found in suprabasal position between the second layer and the fourth layer; in the nail bed, all melanocytes were situated in the first and second layers [3, 5, 19]. Di et al. reported that the average thickness (depth) for subungual pigmented lesions was 0.08mm (range, 0.04 to 0.12 mm), and the thickness of subungual melanocytic nevi ranged from 0.04 to 0.07mm (mean, 0.05 mm) [20]. In our series, there are 5 patients with the width of the pigmented bands ranged from 1/4 to 2/5 of the whole nail, these five patients underwent the aesthetic repair on split-thickness excision of the pigmented nail matrix and nail bed lesions under microscope. No patients recur in a follow-up of over one year. Thus, the aesthetic repair on split-thickness excision of the pigmented nail matrix and nail bed lesions under microscope is reliable and feasible. When the width of the pigmented bands was more than 1/2 of the whole nail width, the split-thickness excision of the pigmented nail matrix and nail bed lesions under microscope can lead to the nail malnutrition or deformity. Thus, the whole nail resection is an option.
The absence of nail may not only influence the appearance and function of the injured foot/hand but also give rise to a psychological burden on the patients due to the poor appearance of the toe/finger. In addition to improving the sensitivity and stability of the toe pulp, the nail also has an aesthetic effect [21–23]. To date, the attention on the aesthetic reconstruction of the fingernail defects continues to be paid[21, 23, 24], whereas the emulational repair and aesthetic reconstruction of the toenail defects has been neglected for a long time. With the popularity of increasingly aesthetic knowledge, aesthetic reconstruction of toenail soft tissue defects possesses increasingly requirements. Therefore, the reconstruction of the toenail soft tissue defects poses a severe challenge for surgeon.
The wound repair following the resection of the whole nail is also a brainteaser. In clinical practice, skin grafts for repairing the nail soft tissue defects with phalanx exposure often presented with the hypertrophic scar at recipient site [16]. The fillet flap with the phalanx shortening often requires the sacrifice of the distal phalanx [15]. Free flap has some disadvantages of long operative time and microsurgical microvascular anastomosis [17]. Currently, few studies focus on the toe pulp flaps for reconstructing the nail defects. Cheng et al reported a lateral toe pulp flap for repairing the dorsal toe defect [25]. Tashiro et al reported a second-toe lateral hemipulp flap transfer to cover a third-toe pulp defect [26]. In our series, mimical reconstruction of the nail following the resection of the whole nail was performed using the lateral toe pulp island flap. All patients obtained the excellent function and aesthetic outcomes, and all patients were satisfied. The lateral toe pulp island flap provides several merits over the use of conventional flaps[15–17], including short operation time, simple flap dissection, minimal donor site morbidities, and outstanding functional and aesthetic outcomes. In addition, the texture and color of the toe pulp is similar to that of the toenail because the toe pulp has a thicker cuticle. This flap can mimic the unique original characteristics of the toenail to minimize deformities. The toe pulp can provide a glabrous skin flap suitable for resurfacing toenail soft tissue defect, realizing sensate reconstruction via “replacing like with like”.