Answer: Serous cystadenoma

Histology: This lesion shows extensive hemorrhage and reactive changes secondary to the fine needle aspiration biopsy performed prior to surgery. The reparative changes obscure much of the lesion. Where they don’t, the neoplasm can be seen to be composed of small cysts lined by clear cuboidal epithelial cells with round uniform nuclei.

Discussion: Serous cystadenomas are usually straightforward lesions to diagnose. In some instances, however, the hemorrhage and inflammation from a prior fine needle aspiration biopsy can obscure the neoplasm. As in this case, the aspirates from serous cystic neoplasms can have a low cellularity, making the diagnosis on fine needle aspiration biopsy difficult.