Background: Sparganosis is not a common disease, and its rarity makes it difficult to distinguish from others. Close examination of fine needle aspiration biopsy (FNAB) samples, however, can aid in histologic examination of the lesion.
Case: A 64-year-old female, born and raised in a rural area in the state of Goiás, Brazil, presented with a relatively mobile and hard lump in the lower inner quadrant of the right breast. It was initially diagnosed as granulomatous mastitis, but cytologic examination of the surgical specimen revealed a sparganum larva, also revealed by anterior FNAB.
Conclusion: Sparganum should be considered in the differential diagnosis of granulomatous mastitis, especially among Asians living in other countries.