Case Presentation:
A 71‐year old Caucasian female presented with a history of invasive ductal carcinoma of the right breast status post neoadjuvant docetaxel, carboplatin, and trastuzumab followed by a left prophylactic mastectomy and right modified radical mastectomy. The patient is currently undergoing radiation therapy in combination with trastuzumab therapy every 3 weeks. The patient presented with complaints of a diffuse rash with intense pruritus which began 5 days after her trastuzumab dose; originating from the right anterior region of her chest and then progressed to her entire trunk, arms, legs, and soles of her feet. On presentation, patient denied any shortness of breath, fever, chest pain, nausea, or vomiting. Dermatology was consulted to evaluate the patient and perform a biopsy of the left thigh to rule out scabies vs. morbilliform drug eruption vs. urticarial vasculitis. On presentation, patient received one dose of hydroxyzine 25mg with no improvement noted in her itching; resolution of symptoms was seen with Solu‐Medrol 125 mg IV. She was immediately started on Solu‐Medrol 60mg IV every 8 hours and hydrocortisone 2.5% topical cream. The punch biopsy of the patient’s left thigh revealed, “superficial and deep perivascular lymphocytic infiltrate with eosinophils/interface dermatitis with spongiosis, consistent with a morbilliform (exanthematous) drug eruption”.
Discussion:
Morbilliform drug eruptions accounts for approximately 95% of cutaneous drug reactions. Although trastuzumab‐induced cutaneous reactions is currently not well established in the literature, there are a few case reports confirming possible radiation recall reaction induced by adjuvant trastuzumab therapy and photosensitive rash linked to porphyrin biosynthesis possibly induced by docetaxel and trastuzumab therapy. Radiation recall dermatitis is a rare complication associated with exposure to a recall‐triggering drug after radiation treatment. An acute reaction can only be termed a radiation‐recall reaction if the recall‐triggering drug is administered at least 7 days after radiotherapy. Otherwise, the reaction may be due to a radiosensitization effect, as the drug interferes with the cellular repair mechanism at work after radiation exposure. Combination therapy with trastuzumab and docetaxel, used in the treatment of metastatic breast cancer, could precipitate cutaneous reactions. Although cutaneous side effects due to trastuzumab therapy are rarely observed, docetaxel has been associated with mild symptomatic and self‐limiting cutaneous eruptions such as erythema multiforme major, photosensitivity, scleroderma, and sub‐acute cutaneous lupus erythematosus (SCLE).
Conclusions:
Although the incidence of trastuzumab‐induced rash is approximately 4‐18%, the acute presentation of the diffuse rash is more likely trastuzumab‐induced worsened by radiation compared to previous docetaxel and trastuzumab combination exposure. The mainstay treatment of morbilliform or maculopapular drug eruptions is the prompt withdrawal of the offending agent when appropriate. Treatment is largely symptomatic; involving the use of oral antihistamines and topical/oral/IV corticosteroids. However, in patients with drug‐induced rash and systemic or cutaneous symptoms, a short course of moderate to high dose systemic corticosteroids may be beneficial. Patient was treated appropriately and tapered off Solu‐Medrol with complete resolution of symptoms.