Periungual Basal cell carcinoma: a case report with review of literature.

Basal cell carcinomas (BCCs) are considered to be uncommon around the nail plate. An indolent lesion of this region should arouse suspicion of potential malignancy and a skin biopsy should be undertaken without delay. Early diagnosis can enable the physician to render simpler nondestructive modalities of treatment. In this article, we describe such a case of longstanding BCC of this region mimicking a traumatic ulcer. The nature of the ailment was finally discovered on biopsy and the carcinoma was initially treated with topical Imiquimod.

Introduction

The commonest cutaneous malignancy among humans is the basal cell carcinoma (BCC) and it usually occurs on sun exposed areas. Those occurring on the periungual area are uncommon[1] and may lead to diagnostic difficulties. The dorsal surfaces of the hands are exposed to the sun but a paucity of pilosebaceous units around the fingernails probably accounts for rarity of BCCs in this area. Tumors in this region challenge the physician's ability to eradicate them. Many therapeutic options have been suggested, such as excision by Moh's surgery, radiotherapy, topical 5-fluorouaracil, intralesional interferon, curettage and electrodessication, cryosurgery, laser and standard excision.[2] Topical Imiquimod, an immunomodulator, has been effective in some cases of BCC. This drug is an imidazoquinolone amine and is known to promote cytokine-mediated cellular immune response.[3] Information about such type of malignancy in this region is rare and extensive search of the English literature revealed 25[4-28] similar cases.

Case Report

A 45-year-old male presented with an ulcerated lesion of the proximal nail fold region of his right thumb [Figure 1]. There was a history of trauma to the part with a wooden board 7 years back which had caused some bleeding and subsequent ulceration. The wound never healed completely and continued to be painful and was tender to touch. Slightest trauma would result in bleeding followed by crusting. The lesion had been variously treated with topical and systemic antibiotics.

Figure 1

Periungual BCC, presenting as a painful, non-healing ulcerated lesion

Routine blood, stool and urine examinations were normal as was the chest X-ray. A 3-mm punch biopsy of lesional skin was performed and histopathology revealed presence of solid islands of basaloid cells in upper dermis without much pleomorphism and without any mitotic figure [Figure 2]. Palisading was absent. There were no horn cysts. The subject was instructed to apply topical Imiquimod (5%) cream with the help of cotton tipped sterile tooth pick over the affected area at bedtime, 5 times a week, washing it off the next morning. Each sachet of Imiquimod contained 12.5 g of the drug and the patient had to use up this amount in a week. Treatment was prescribed for 6 weeks and he had to report every 15 days. Four weeks after starting the drug, the person returned complaining of intense pruritus, erythema, and some pain. He was unwilling to continue topical Imiquimod, was extremely anxious as he had come to know of the biopsy report and was referred to the surgery department for suitable operative maneuver. The case was lost to follow-up.

Figure 2

Basaloid cells in upper dermis in a case of periungual BCC (H and E, 10×)

Discussion

The nail unit is an important structure which needs to be preserved. Tumors like BCC around this region have to be identified early so that destructive surgery can be avoided. There are different modalities of treating a carcinoma of this nature and topical Imiquimod cream provides a possibility of cure without compromising the structures of this region.

A review of the English literature of BCCs of the nail unit showed the average age at presentation to be 65 years, with the youngest reported case of age 36 years and the oldest of 88 years. Male: female ratio was 1.8:1. The thumb was the most frequently affected site[568912131519242628] and the hallux was reported in five cases.[1118212227] The right middle finger was involved in three cases[41620] and both hands were affected with almost similar frequency.

Most nail unit BCCs were misdiagnosed as infective disease,[81318] chronic eczema,[91523] or other benign[10] and malignant neoplasms.[111215-172227] Classic features with a rolled out border were described only in a few of the reported articles.[111618] Thus, a skin biopsy should be carried out at the earliest hint of suspicion to diagnose these cancerous tumors.

Presentation varies from onycholysis[610] to longitudinal melanonychia,[1217] and the most common sign of the disease is ulceration[78141618202124-26] around and of the nail plate, as seen in our subject.

Trauma could have been an inciting factor in our case, while others[28] reported a case of BCC of the nail unit in an angler who had the habit of coloring his baits with an azo dye to attract the fishes. The dye was incriminated in the causation of the carcinoma.

Time to diagnosis of the malignancy varies from 8 months[26] to 40 years[11] and there were at least five subjects[710-1222] whose malignancy was diagnosed after 15 years or more.

Surgical maneuvers are preferred in most cases and Moh's micrographic surgery was performed with excellent results in many of the patients.[91213151824-2628] Other cases were subjected to excision with or without amputation.[7101116171920-2327]

Topical 5% Imiquimod has been used successfully to treat cases of superficial, nodular and pearly BCCs.[2] The exact mechanism of action of Imiquimod in BCC is not known but it is thought that Imiquimod acts on toll-like-receptor-7 (TLR-7) present on dendritic cells, macrophages and monocytes and stimulates the expression of interferons, Th-1 cytokines, tumor necrosis factor alpha and G-CSF. Th-2 cytokines which are raised in BCC are thereby neutralized. It thus promotes tumor surveillance.[29] Others[30] have suggested that tumor regression is achieved probably by induction of Fas receptors on the tumor cells, resulting in their apoptosis.

Different regimes of topical 5% Imiquimod have been used to treat BCCs. Patients have been known to apply the cream once daily, twice daily and in thrice weekly regimes.[31] We chose once daily application 5 days in a week. The end result of this therapy was not encouraging and the patient was not ready to tolerate the side effects.

Early malignancy of the nail unit, of basal cell in nature, is not as uncommon as before but may be difficult to diagnose due to its rarity. A high index of suspicion is necessary while dealing with nonhealing ulcers of this region. Electrodessication or more extensive surgical intervention is often not possible in elderly patients or those having underlying illness, mental disease or coagulation disorder. Surgical excision is refused by many patients fearing cosmetic disfigurement. Topical 5% Imiquimod may provide an encouraging treatment modality if instituted early though it may have local side effects.

We report this case to draw attention of all physicians, urging them to practice early suspicion of all nonhealing lesions around the nail to be of possible malignant origin.