Background: Although the cytologic features of fibroadenoma are well established, some of the smears from these tumors cause serious diagnostic problems.
Case: In the cytologic smears from a deeply located breast nodule in a 53-year-old female we found, besides the typical features of fibroadenoma, atypical cells suggesting carcinoma, with intranuclear indentations, nuclear molding, mitotic activity and intracytoplasmic vacuoles. Histologic examination confirmed the diagnosis of fibroadenoma, but marked ductal cell hyperplasia was also revealed.
Conclusion: Some disturbing atypical changes may occur in fibroadenoma smears.