RESUMO
Azathioprine (AZA) treatment in transplant or autoimmune patients and subsequent appearance squamous cell carcinomas at various sites, particularly skin and cervix, has shown a close relationship. However, it remains uncertain whether this is true for the patients with Crohn's disease. We report a case of squamous cell carcinoma of the breast occurred in a 35-year-old female with Crohn's disease taking AZA. She was first diagnosed with Crohn's disease 10 years ago and has taken AZA with 5-aminosalicylic acid (5-ASA) on regular follow up in gastrointestinal department for 9 years. She had no family history of breast cancer. She visited breast cancer clinic due to incidentally found right breast mass. A mastectomy on the right breast was performed and 6.3x5.5 cm mass was removed. The mass was microscopically proven to be poorly differentiated squamous cell carcinoma with focal keratin pearl formation. At age of 25, she was first diagnosed with active Crohn's disease. 5-ASA and corticosteroid induced remission. Then, steroid was tapered off and AZA was maintained at 1 mg/kg due to leukopenia at higher dose. She stopped taking AZA at her discretion during her two pregnancies and reported total of 67 months of AZA medication on her breast cancer diagnosis.