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Acute interstitial pneumonitis following adjuvant tamoxifen therapy.

e11637 Background: Tamoxifen is a serum estrogen receptor modulator that is widely used in the treatment of women with breast cancer and has a low incidence of serious side-effects. Although hypersensitivity reactions to tamoxifen have rarely been described, to our knowledge acute lung toxicity has not previously been reported.


OBJECTIVE
To report an unusual case of acute interstitial pneumonitis in a patient with early stage breast cancer treated with tamoxifen.


RESULTS
A 66 year old post-menopausal woman with past medical history of type 2 diabetes mellitus, and hypertension noted a lump in the right breast. An excision biopsy revealed 9 mm moderately differentiated invasive ductal carcinoma. Lymph nodes were not involvd by the tumor. The tumor cells were positive for estrogen and progesterone receptors and were negative for ErbB-2 over expression. The post operative course was complicated by wound infection treated with combination of clindamycin and ciprofloxacin. The patient was recommended adjuvant tamoxifen. Her other medication were metformin, valsartan, calcium and vitamin D. One week after the commencement of tamoxifen she noted increasing dyspnea, cough, and intermittent fever. X-ray chest showed bilateral lung infiltrates. She was hospitalized and treated with broad spectrum antibiotic. The patient condition deteriorated. She developed acute respiratory failure requiring intubation and mechanical ventilation. Tamoxifen was discontinued. A CT scan of chest showed bilateral interstitial infiltrates. Bronchoalveolar lavage was performed which was negative for infection. An open lung biopsy was done which showed focal diffuse alveolar damage consistent with interstitial pneumonia. No evidence of an infective agent, malignancy, or granuloma was noted. The patient was treated with high dose steroid. She gradually recovered and was discharge to home with normal lung function.


CONCLUSIONS
Drug-induced lung injuries are usually idiosyncratic reactions and occur in an unpredictable manner. The presence of a temporal relationship between the lung injury and tamoxifen administration, a rapid clinical improvement after discontinuation of the drug, and absence of other causes strongly implicated tamoxifen as a potential cause of acute lung injury. No significant financial relationships to disclose.