Tattoo-induced pseudolymphoma

Introduction Pseudolymphoma is a rare complication of tattooing, presenting with infiltrated areas often at the site of a red tattoo and postulated to be an allergic reaction to mercury salt. When present, it may be mistaken for the more commonly occurring tattoo-associated granuloma. Case summary We describe a 47-year old female who developed nodular areas on her tattoo four months after placement by a professional tattoo artist. The nodules were restricted to the red regions and spared the blue-black areas of tattoed skin. Initial differentials included a foreign body or sarcoidal granuloma and contact dermatitis to the red dye. Histology revealed a top-heavy lymphocytic infiltrate spanning most of the dermis, with numerous eosinophils. Dark red, non-polarisable exogenous pigment was scattered throughout the dermis, in association with the inflammatory infiltrate. The epidermis showed intense spongiosis and eosinophilic exocytosis. A final diagnosis of tattoo-induced pseudolymphoma was made. Pseudolymphoma, foreign body and sarcoidal granulomatous reaction patterns from tattoos occur more commonly in red tattoos. Biopsy with histology is required to differentiate these three disorders with divergent management. We review the literature on tattoo-induced pseudolymphoma and highlight the pitfalls associated with the diagnosis.

Narrowband UVB-induced lichen planus pemphigoids

Introduction: Lichen planus pemphigoides (LPP) is a rare acquired autoimmune disease characterised by the evolution of subepidermal blisters on normal and lichen planus affected skin. Case summary: We describe a case of lichen planus pemphigoides in a 54-year-old Chinese woman. The patient presented initially with scaly psoriasiform plaques and was diagnosed to have guttate psoriasis. She was treated with narrowband ultraviolet (NBUVB) therapy twice weekly. Within a month of starting phototherapy, she experienced a flare up of her skin lesions with a generalised eruption of violaceous papules, tense bullae over the lower limbs as well as Wickham’s striae over the buccal mucosa. Histology of the violaceous papule over abdomen revealed interface dermatitis, while the specimen from a blister showed subepidermal bulla with linear deposition of IgG and C3 along the basement membrane zone. A diagnosis of LPP was made on clinicopathological grounds. The patient subsequently responded well to oral prednisolone at a dose of 0.5 mg/kg/day. Conclusion: This is the first case report of NBUVB alone unmasking LPP. In the presentation, we will describe the pathological mechanism of NBUVB in the development of LPP and the key features distinguishing LPP from bullous lichen planus (BLP), psoriasis and bullous pemphigoid (BP).