Image Quiz: Cytology—A chalky white-filled lesion in a German shepherd

May 12, 2011

A 2-year-old German shepherd is presented for evaluation of a subcutaneous nodule over the olecranon region of the elbow. The nodule is extremely firm, and material obtained through fine-needle aspiration is gritty and chalky white. Unstained, with the microscope condenser lowered, the material appears refractile. After staining with Wright's-Giemsa stain, little is apparent except for a stippled background, small numbers of red blood cells, and occasional macrophages—a few that are multinucleated.

What is the most likely diagnosis for this lesion?

a) Lipoma

b) Hygroma

c) Osteosarcoma

d) Calcinosis circumscripta