Epidermal necrosis with multinucleated keratinocytes: a possible diagnostic clue for dermatitis artefacta in children

Editor Dermatitis artefacta (DA) is a rare disorder, characterized by self-inflicted cutaneous lesions. DA typically occurs in adolescents and young adults, often with a history of psychiatric disorders. Histopathology is often non-specific, although epidermal necrosis is common. Herein, we describe three adolescents with clinical findings suggestive of DA and multinucleated keratinocytes in their biopsies. A 13-year-old female with attention deficit hyperactivity disorder presented with a 3-month-history of multiple tender erythematous well-defined round patches and erosions located on the right thigh (Fig. 1a). One month after onset, the patient was changed from dexmethylphenidate to lisdexamfetamine, but the lesions persisted. A 15-year-old female presented with an intermittent eruption that started on the arms and spread to the legs, cheeks and neck. The lesions started with tender well-demarcated erythematous plaques and evolved into hyperpigmented patches (Fig. 1b–c). Her family history was significant for bipolar disorder and DA in a sibling. During a 2-year period, new lesions continued to develop. A 12-year-old female presented with an 8-month history of bullae on the arms and sharply demarcated, deeply erythematous plaques with multiple shapes and polygonal borders. Outbreaks lasted 2 weeks and extended to the face and limbs. The patient reported bullying at school due to the lesions and was allowed to remain home during flares. She had been treated with multiple topical medications without improvement. In all patients, laboratory studies were within normal limits. All patients and their caregivers denied skin manipulation. Skin biopsies from active lesions of each patient showed epidermal necrosis and syncytial keratinocytes in the epidermis, with some of these cells harbouring up to 20 nuclei (Fig. 2a–b) and showing a morula-like appearance (Fig. 2c), reminiscent of multinucleated cells seen viral infections. However, other cytopathic changes were not identified. Additional biopsies showed foci of subepidermal bullae without immune deposits (Fig. 2b). No history of herpetic infections, medication changes or drug allergies were reported. Based on the geographic clinical appearance, psychiatric histories in patients 1-2, psychological stressors at school in patient 3, histological epidermal necrosis and lack of infectious or autoimmune aetiologies, all patients were diagnosed with DA. Multinucleated cells are often encountered in skin biopsies and can be mesenchymal or epithelial. Histiocytic multinucleated giant cells are most frequently seen, usually related to infection, inflammatory or reparative conditions. Multinucleated epithelial cells (MEC), also called syncytial keratinocytes, are less frequent, and may be seen in viral infections (Herpesviridae, measles, monkeypox) epidermal tumours, (trichoepitheliomas, basal cell carcinomas) and inflammatory disorders. In these conditions, MEC display 2–3 nuclei per cell. In our series, all biopsies displayed epidermal necrosis and MEC with a myriad of nuclei. DA is a self-inflicted dermatosis presenting with lesions in areas which the patient can reach, and demonstrate geometric or bizarre configurations. Methods implicated in DA include cutting, stabbing, thermal burns and aerosol sprays. Deodorant spray has recently been implicated in four cases of bullous DA in teenagers. While all four cases showed epidermal necrosis, two showed numerous MEC, similar to ours. In summary, the diagnosis of DA is challenging, especially in the paediatric population given the denial from patients and