INTRODUCTION
Subungual melanoma (SUM) is an uncommon form of acrolentiginous melanoma that represents about 0.7 to 3.5 percent of all subtypes of melanoma.1,2 Amputation was long thought to be the best treatment for SUM; however, recently SUM in situ and minimally invasive SUM (Breslow thickness, less than 0.5 mm) have been treated conservatively using non-amputative wide local excision (“functional” surgery) in order to decrease morbidity and preserve digital function and the patient’s self-esteem.3,4 Nevertheless, in some cases, surgery is not possible because of patient´s preferences, comorbidities, functional impairment, or positive margins after multiple surgeries. In these cases, other non-surgical treatments have been suggested.5,6 The aim of this paper is to report a case of SUM in situ that recurred after functional surgery of the nail apparatus and was treated successfully with two cycles of imiquimod 5%, without relapse after 4 years of follow up.
CASE REPORT
An 82-year-old Caucasian male patient presented with a 15-year history of an asymptomatic pigmented macule on his left great toenail with no previous history of trauma. Close inspection revealed a hyperpigmented macule involving the proximal nail fold and the hyponychium as well as a longitudinal melanonychia with an irregular pattern and splinter hemorrhages in the nail plate of the left great toenail (Figure 1A). Further physical examination did not reveal palpable lymph nodes. With the presumptive diagnosis of SUM, a non-amputative wide local excision as a diagnostic and therapeutic approach was performed, removing the entire nail unit and the periosteum of the distal phalanx with a lateral safety margin of 5 mm, followed by a skin graft (Figure 1B). Histological examination confirmed the diagnosis of subungual melanoma in situ with tumor-free margins (Figure 1C). There were no significant findings in the laboratory or imaging tests.Eight months later, the patient presented an irregular pigmentation at the site of surgery (Figure 2A). A skin biopsy was performed confirming the diagnosis of a recurrent subungual melanoma in situ. Due to the advanced age of the patient and the family request (they did not consent to another surgery), therapy with topical imiquimod 5%, five times a week for five months, was initiated, decreasing significantly the pigmentation (Figure 2B).Seven months after the treatment with imiquimod 5%, a hyperpigmented macule in the same site was observed (Figure 2C), and a new biopsy revealed again the diagnosis of SUM in situ. Another cycle of imiquimod 5% five times a week for five months was performed (Figure 3A). The patient presented total regression of the lesion and has remained in clinical remission for 4 years (Figure 3B).
