Nickan Research Institute Immunopathologia Persa 2423-8015 10 1 2024 01 01 Maxillary sinus metastasis in breast cancer; a case report and review of the literature e16212 e16212 10.34172/ipp.2022.16212 EN Maryam Ghazizadeh https://orcid.org/0000-0002-6852-4092 Matin Ghazizadeh https://orcid.org/0000-0002-3755-3499 Journal Article 10.34172/ipp.2022.16212 2020 08 08 2020 10 20 Paranasal sinuses are an infrequent site for tumor metastasis, and breast cancer metastasis to these sinuses is very rare. To date, less than 20 cases of breast cancer metastasis to paranasal sinuses have been reported. This case study’s purpose was to describe a 69-year-old woman with a history of breast cancer treated 15 years ago who developed the symptoms of rhinosinusitis. Physical examination showed exophthalmos and maxillary sinus tenderness. Finally, breast cancer metastasis to paranasal sinuses was diagnosed using CT scan. She received hormone therapy, systemic chemotherapy, and maxillary sinus radiotherapy. The treatment was well tolerated, and lesions observed in CT scan improved and after more than a year the patient is still alive.