Author: Richard  Cantley, MD, Cytopathology Fellow,
Northwestern University, Feinberg School of Medicine,Chicago, IL 60611

Reviewer: Walid Khalbuss, MD, FIAC

A 59 year old female presented with right upper quadrant abdominal pain.  A 4.9 cm unilocular cystic hepatic mass was discovered on MRI.  Aspiration of the cyst fluid was performed.  Four cytospin slides (2 Diff Quik stained and 2 Papanicolaou stained) and one Hematoxylin and Eosin (H&E)-stained cell block slide were prepared.  Immunohistochemical stains performed for ER and PAX-8 on cell block material were negative.

Image 1, Diff-Quik Stain, 200x

Image 2, Diff-Quik Stain 400x

Image 3, Diff-Quik Stain 400x

Image 4, Papanicolaou Stain 400x

Image 5, Cell Block, H&E stain 400x

Which of the following is the correct diagnosis?