Incidence and Epidemiology of Pancreatic Cystic Neoplasms

Cystic neoplasms

Serous cystic neoplasms (SCNs)

Mucinous cystic neoplasms (MCNs)

Intraductal papillary mucinous neoplasms (IPMNs)

Uncommon cystic neoplasms

Solid pseudopapillary neoplasm

Cystic neuroendocrine neoplasms (functional and nonfunctional)

Acinar cell cystadenocarcinoma

Angiomatous neoplasm (angioma, lymphangioma, hemangioendothelioma)

Cystic teratoma

Cystic choriocarcinoma

Acquired cystic lesions

Pancreatic pseudocyst

Pancreatic pseudopseudocyst (inflammatory exudative collection)

Postinflammatory cystic fluid collection

Acute necrotic collection

Walled-off necrosis

Echinococcal (hydatid) cyst

Parasitic cysts

Taenia solium cyst

Congenital cysts (true cysts)

True cysts (rare primary pancreatic cyst)

Pancreatic cysts associated with polycystic disease of the kidneys

Polycystic disease of the pancreas without related anomalies

Pancreatic macrocysts associated with cystic fibrosis

Polycystic disease of the pancreas associated with cerebellar neoplasms and retinal angiomata (von Hippel-Lindau disease)

Enterogenous cysts (duplication cysts)

Endometriosis dermoid cysts

Modified from Sakorafas et al. [36]

Increased awareness and improved sensitivity of imaging is associated not only with increasing detection rates but also with decreasing lesion size [10–13]. These factors only increase the clinical challenges involved in determining which patients require either more investigation, surveillance, or resection. Ferrone et al. compared data for the periods 1997–2002 and 2004–2007 and noted that the proportion of asymptomatic patients being referred to PCNs increased from 36 to 71 %; interestingly, the proportion undergoing resection decreased from 80 to 50 % [11]. Recently, it has been reported that the median size of cystic lesions of the pancreas in patients being referred for lesions sent for evaluation halved from 4 to 2 cm over the last 5-year period [14, 15]. Ferrone and colleagues reported a similar decrease in the size of lesions referred from 3.3 to 2.7 cm [11].

PCNs were considered previously to be a rare entity, being identified during transabdominal ultrasonography in 0.2 % of studies [16]. Currently, PCNs have become a surprisingly common clinical problem, accounting for 10–15 % of all cystic lesions of the pancreas [17, 18]. The vast majority (~90 %) of PCNs are serous cystic neoplasms (SCNs), primary mucinous cystic neoplasms of the pancreas (MCNs), or IPMN [3, 19, 20] (Tables 2.1 and 2.2). Other rare types of PCNs (solid pseudopapillary neoplasms, cystic neuroendocrine neoplasms, etc.) account for about 10 % of all cases of PCNs.

Table 2.2

Features of PPNCs: Clinical and imaging

	Pseudocyst	SCN	MCN	IPMN	SPPT	Lymphoepithelial cyst
Clinical
Sex ratio (M/F)	1:1	1:3–4	1:9	1–2:1	1:10	4:1
Age, range (year)	30–50	60–80	30–50	60–80	15–40	30–80
Prior pancreatopathy	Pancreatitis	None	None	May have symptoms of acute or more commonly chronic pancreatitis	None	None
Findings on cross-sectional imaging
Location in pancreas	Most commonly neck/body	Head>body/tail	Body/tail>>head	Head>body/tail	Evenly distributed	Most commonly body/tail
Uni-/multicentric	Unicentric	Unicentric	Unicentric	Unicentric, but can be multicentric	Unicentric	Unicentric
Characteristics of lesions	Uni-/multiloculated rounded shape macrocysts, pericystic inflammation reaction, findings of pancreatitis	Multiple, small (<2 cm) microcysts; rarely a unilocular macrocyst; characteristic central stellate calcification (~30 %)	Unilocular or multiloculated macrocysts >2 cm, smooth external contour	Irregular, polycystic mass with dilation of main and/or branch ducts	Large, encapsulated solid/cystic mass, “cystic” areas	Encapsulated, uni- or more commonly multiloculated cyst in and/or around the gland
Findings suggestive of malignancy	None	Rare <1 % serous cystadenocarcinoma, invasive and/or metastatic lesions	Eggshell calcification, solid component, or mural nodule	Main duct (dilation, >1 cm), branch duct lesion (>3 cm with solid component), mural nodules; systemic symptoms – weight loss, jaundice	Metastatic disease (rare, usually present at diagnosis)	None
Findings on ERCP/MRCP
Communication of cystic area with pancreatic duct	Present	Absent	Absent	Present. Main or side branch dilation	Absent	Absent
Findings on EUS
	Unilocular macrocystic lesion, internal debris, thick wall, pericystic reaction	Microcystic, honeycombed, rarely macrocystic, no pericystic reaction	Macrocystic, septae within the “cyst,” no pericystic reaction	Dilated pancreatic duct (main duct or side branches)	Mixed solid and cystic lesion	Thin-walled, heterogeneous, subtle posterior enhancement

Modified from Sakorafas et al. [36]

SCNs account for over 30 % of PCNs and for 1 % of non-endocrine pancreatic neoplasms. SCNs arise anywhere in the pancreas, with most cases occurring in the pancreatic head [21, 23] (Table 2.2). In a multicenter study from Japan, SCNs were located in the pancreatic head, body, tail, and uncinate process in 39, 35, 22, and 3 % of patients, respectively [22]. SCNs typically occur in women over the age of 60, with a female to male ratio of 70:30 [24, 25]. In a study from the Massachusetts General Hospital, Tseng et al. [25] reviewed 106 patients with SCNs of the pancreas, 75 % of whom were females. Mean age at presentation was 62 years, but the mean age of males was >7 years older than that of females, and males had larger tumors at presentation, suggesting a delay in diagnosis in men [25].

MCNs occur almost exclusively (>95 %) in middle-aged/perimenopausal females [26–28]. Literature in the past suggested a much more common prevalence in men than we appreciate currently; in retrospect, most of these lesions in men were IPMNs and not MCNs. This topic will be discussed below. The incidence of MCNs peaks in the fifth decade of life [29, 30]. MCNs arise in the body and tail of the pancreas in approximately 95 % of patients [23].

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