Matthäeus Cunha Bürger - Department of Radiology, Clementino Fraga Filho University Hospital, Federal University of Rio de Janeiro, Rio de Janeiro, RJ, Brazil
Edson Marchiori - Department of Radiology, Clementino Fraga Filho University Hospital, Federal University of Rio de Janeiro, Rio de Janeiro, RJ, Brazil
Maria Celia R.Djahjah - Department of Radiology, Clementino Fraga Filho University Hospital, Federal University of Rio de Janeiro, Rio de Janeiro, RJ, Brazil
Nathalie Cruz da Silva Bürger - Department of Radiology, Clementino Fraga Filho University Hospital, Federal University of Rio de Janeiro, Rio de Janeiro, RJ, Brazil
Ana Helena Correia - Department of Pathological Anatomy, Clementino Fraga Filho University Hospital, Federal Universityof Rio de Janeiro, Rio de Janeiro, RJ, Brazil

Background: Breast leiomyosarcoma is a rare subtype of breast sarcoma,constituting ۵–۱۰% of the cases. Less than one-third of reported cases are locatedin the nipple papillary region, making it an extraordinarily rare malignancy,responsible for less than ۰.۱% of all malignant breast tumors. As no radiologicalcriteria allow definitive diagnosis of papillary leiomyosarcoma, histopathologicaland immunohistochemical examination of suspicious lesions is required. Theprognosis is generally optimistic compared with those for other breast sarcomas.Case presentation: A ۵۴-year-old previously healthy woman reported theappearance of a nodule in her right nipple in the preceding ۹ months, associated withpruritus. Physical examination revealed that the lesion had a cystic consistency andmeasured approximately ۳.۰ cm. Imaging examinations showed no involvement ofthe adjacent breast parenchyma or axillary region and the lesion was classified asBreast Imaging-Reporting and Data System (BI-RADS) category IV. The lesionwas excised, and the histopathological diagnosis was well-differentiatedleiomyosarcoma of the mammary papilla, with immunohistochemical examinationshowing positivity for smooth-muscle tissue antigens. A staging CT examinationwas performed, showing no evidence of distant metastasis. After ۲ years of followup,the patient shows no sign of tumor recurrence.Conclusion: Although rare, leiomyosarcoma must be included in differentialdiagnosis of breast masses, especially those involving the periareolar region. Due toits good prognosis, reporting on this type of tumor is important to guide therapeuticplanning, and to identify and track possible complications of its underdiagnosis.

Leiomyosarcoma, breast papilla, magnetic resonance imaging