Notes:

Interval growth of cyst: For cysts < 0.5 cm, growth is represented by a 100% increase in long-axis diameter; for cysts >= 0.5 cm and < 1.5 cm, a 50% increase in long-axis diameter; and for cysts >= 1.5 cm, a 20% increase in long-axis diameter.
 
If the lesion has interval growth during the follow-up, but has been stable again since, please follow the “interval growth” follow-up algorithm.
 

Radiologists have the option to recommend endoscopic ultrasound/FNA instead of follow-up imaging in this situation. If the lesion is associated with mild MPD dilatation (2-7 mm), a lot of time one cannot differentiate between combined form IPMN (both side branch and MPD involved) versus pure branch duct form IPMN (the dilatation of the MPD is due to secreted mucus plugging the duct). In this case, it may be prudent to recommend endoscopic ultrasound/FNA directly. Also, if the lesion is relative big (close to 2.5 cm) or has been growing relatively fast, it may be prudent to recommend endoscopic ultrasound/FNA directly.