Pseudoepitheliomatous hyperplasia - an unusual reaction following tattoo: report of a case and review of the literature.

A 59-year-old woman presented with an itchy and uncomfortable raised lesion at a tattoo site (Fig. 1) on the lateral aspect of the left leg, just above the ankle. The tattoo had been placed 2 years before her presentation and the tattoo site was sun exposed. Immediately after she had the tattoo, she noticed redness of the skin. After a week, a pruritic and red scaly nodule developed that continued to gradually enlarge until her presentation. The patient had tried topical vitamin A and D ointment with no relief. The patient also had tattoos on the arms without any noticeable skin changes. The patient reported that the tattoo procedure on her leg was more painful than that on her arms, and was performed by a different (and perhaps inexperienced) tattoo artist. The original tattoo contained red, green, and yellow pigments. A diagnosis of tattoo granuloma was considered; squamous cell carcinoma and fungal infection were included in the differential diagnosis. A punch biopsy was performed, followed by complete surgical excision of the lesion with a split-thickness skin graft from the right thigh. The skin excision specimen showed a 3 x 2.5-cm granular and pitted pink lesion with well-demarcated, somewhat irregular borders. The lesion was raised 0.5 cm above the skin surface. The lesion was present in the center of the original tattoo. Portions of the original tattoo with green and blue-green pigmentation were visible on either side of the lesion. No satellite lesions were identified. Microscopically, the raised lesion demonstrated striking pseudoepitheliomatous hyperplasia, with irregular acanthosis of the epidermis and follicular infundibula, hyperkeratosis, and parakeratosis (Fig. 2). Follicular plugging was present with keratin-filled cystic spaces. There was a brisk mononuclear inflammatory infiltrate in the dermis, composed primarily of lymphocytes, with admixed plasma cells and histiocytes. Giant cells were occasionally identified. Dermal pigment deposition was noted both within the lesion and in the surrounding skin, corresponding to the original tattoo. Variable dermal fibrosis was noted, with thick collagen bundles in some areas. There was no evidence of epidermal keratinocytic atypia, dyskeratosis, or increased suprabasal mitotic activity. Special stains (periodic acid-Schiff and acid-fast) for microorganisms were negative.