Mitotic rate may be moderate to high, may have atypical forms
May have insular or trabecular pattern
Insular and trabecular patterns unusual
Not associated with overlying adenoma
May be associated with overlying adenoma
50% have psammoma bodies
Psammoma bodies not seen
Somatostatin diffusely positive
Somatostatin negative
Synaptophysin usually positive, chromogranin may be positive
Synaptophysin, chromogranin negative
The frequent glandular pattern and invasion seen in somatostatinomas make this a more difficult distinction than for many other well differentiated gi endocrine neoplasms
