TABLE 2.

Characteristics of Small (≤ 3 cm) Cystic Pancreatic Neuroendocrine Tumors (NETs)

Case No.	Cystic Change on CT	Size (cm)	Location	Peripheral Enhancementa			CT Diagnosis or Differential Diagnosis	Gross Pathology
				Arterial Phaseb	Venous Phaseb	CT Appearance (Internal Enhancing Structures)
1c	≈ 100%	0.9	Head	−	−		Indeterminate, possible IPMN	Contained cystic component
2	≈ 100%	1.7	Tail	±	−	Equivocal, thin, smooth	Known pancreatic NET	Contained cystic component
3	≈ 100%	0.7	Tail	−	−		Indeterminate, possible IPMN	Contained cystic component
4	> 50%	2.4	Tail	++	+	Thin and thick, crescentic	Pancreatic NET, MCN	Contained cystic component
5	> 50%	1.4	Tail	+	±	Medium thickness, smooth	Pancreatic NET	Contained cystic component,  focal necrotic component
6	> 50%	0.9	Body	+	−	Thin, smooth	Known pancreatic NET	Contained cystic component
7	> 50%	1.8	Tail	+	+	Medium thickness, irregular	Pancreatic NET, primary cystic  neoplasm	Contained cystic component
8	> 50%	1.8	Neck	+	++	Medium thickness, smooth	Pancreatic NET	Contained cystic component
9	> 50%	1.5	Tail	+	±	Thin and medium thickness,  smooth	IPMN, cystadenoma,  pseudocyst	Contained cystic component,  hemorrhagic component
10	> 50%	1.5	Tail	+	−	Medium thickness, smooth	Indeterminate, possible IPMN	Contained cystic component
11	≤50%	2.8	Head	+	++	Medium thickness, irregular  (predominantly solid)	Pancreatic NET	Contained cystic component,  hemorrhagic component
12c	≤50%	2.3	Tail	+	±	Thin and thick, smooth  (predominantly solid)	Pancreatic NET	Contained cystic component
13	≤50%	3.0	Head	++	+	Thin and thick, smooth  (predominantly solid)	Indeterminate cystic lesion	Solid
14	≤50%	1.4	Head	++	−	Thin and medium thickness,  smooth (nodular)	Pancreatic NET, other  neoplasm	Contained cystic component,  hemorrhagic component
15	≤50%	2.5	Head	++	+++	Medium thickness and thick,  irregular (predominantly  solid)	Pancreatic NET	Contained cystic component

Note—IPMN = intraductal papillary mucinous neoplasm, MCN = mucinous cystic neoplasm.

^aPeripheral enhancement was classified as smooth or irregular and as thin (≤ 3 mm), medium (> 3 and ≤ 6 mm), or thick (> 6 mm).

^bDegree of peripheral enhancement was quantitatively graded by obtaining the difference of average attenuation of an enhancing component and of normal pancreatic parenchyma at the arterial phase and portal venous phase: − = ≤ 10 HU, ± = between 10 and ≤ 20 HU, + = between 20 and ≤ 40 HU, ++ = between 40 and ≤ 60 HU, or +++ = >60 HU.

^cMultiple endocrine neoplasia type 1.