Psoriasis Induced by Trastuzumab (Herceptin®)
A 57-year-old woman was referred to our dermatologic outpatient clinic for the evaluation and treatment of psoriatic skin lesions after the trastuzumab treatment for breast cancer. She had been diagnosed with invasive ductal carcinoma of the left breast in August of 2009. She had been in relatively good health without any medical problems, and she had no personal or family history of psoriasis.\nAfter the surgical removal of the left breast, she was treated with trastuzumab every 3 weeks for the HER2+ breast cancer from November 2009 to the time of our examination. A few months after the treatment began, she developed erythematous and scaly plaques on her extremities (). She was treated with a combination of the ultraviolet B phototherapy and a topical steroid, and her skin lesions improved. However, when trastuzumab was re-administrated, the skin lesions were exacerbated without other possible aggravating factors.\nA skin biopsy from a typical lesion of the left leg showed the typical features of psoriasis, with parakeratosis, epidermal hyperplasia, elongation of the rete ridges, dilated capillaries in the dermal papillae, and a lymphocytic and polymorphonuclear cell infiltrate in the dermis (). Because her skin condition responded well to the treatment with a topical steroid and phototherapy, the discontinuation of trastuzumab was not required.