Conflicts of interest:None declared.To the Editor, Skin photosensitivity induced by drugs is a side effect that occurs as a consequence of exposure to ultraviolet or visible light. It accounts for 8% of all side effects to drugs.This type of reaction can be classified as photoallergic or phototoxic based on its pathogenesis. Despite a detailed medical record, a good physical examination, a histological study and skin phototest and patch test, in many cases it is not possible to determine whether the skin photosensitivity is due to one mechanism or the other.The drugs that most frequently produce photosensitizing reactions are amiodarone, chlorpomazine, doxycycline, tetracycline, hydrochlorothiazide, nalidixic acid, naproxen, piroxicam, thioridazine and voriconazole. We present the first case of photosensitivity to lenalidomide (1).
CASE REPORTAn 89-year-old male without any known drug allergies presented with a history of arterial hypertension, being treated with furosemide 40 mg and a myelodysplastic syndrome, of refractory cytopenia type, with multilineage dysplasia with a chromosome 5q anomaly. Since he was diagnosed he has needed several transfusions and erythropoetin. Despite this his blood tests showed leukocyte 27000/μl, haemoglobin 7.9 g/dl, hematocrit 29%, platelet 74.000/μl, urea 84.7 mg/dl, serum creatinine 1.3 mg/dl. Consequently it was decided to introduce one daily treatment of 10 mg of lenalidomide.Ten days after, the patient went to the hospital suffering from an erythematous purpuric eruption, scaly and pruritic, in those areas exposed to light (face, the dorsum hands and the neck) even in those areas covered by a thin layer of clothes (arms, thighs, legs and the top of both feet) (Fig. 1). What stands out in the blood test is the existence of 23.000 μl leukocytes, haemoglobin 9.5 g/dl, hematocrit 29%, platelet 18.000/μL, urea 206 mg/dl, serum creatinine 1.4 mg/dl. The porphyrins in urine, faeces, blood and autoimmunity tests were negative, including anti-nuclear antibody, anti-Ro, anti-La and anti-histone antibodies. We suspected that lenalidomide was the cause of the photosensitivity and the thrombocytopenia so treatment with it was suspended.A skin biopsy showed a normal thickness of the epidermis, with orthokeratosis, spongiosis, vacuolization of some keratinocytes and the presence of some necrotic keratinocytes. Numerous extravasated erythrocytes were found in the dermis, as well as a superficial inflammatory infiltrate at an interstitial and perivascular level mainly formed by lymphocytes and some neutrophils (Fig. 2).After stopping the medication there was a progressive improvement of the lesions, resolving after a month, nevertheless the purpura persisted. Despite the maintenance treatment with erythropoietin and blood transfusions, the patient continued to show significant cytopenias and his renal function worsened. His general condition deteriorated and he died 3 months later.
