SCAs are benign tumors that exhibit an indolent growth pattern. They are more commonly found in women, with a median age of 58 years at diagnosis [11]. Many SCAs are diagnosed incidentally on imaging studies, as up to 61% of patients are asymptomatic [11]. Malignant transformation to cystadenocarcinoma is extremely rare, reported to be as low as 0.1%, and SCA-specific mortality is reported to be nearly zero [11].
Given the benign natural history of SCA, observation of asymptomatic patients is typically recommended. There is currently no consensus on management strategies, with recommendations ranging from surveillance for asymptomatic patients to surgical resection, depending on various factors such as SCA size, location, or growth rates. [1, 3–4, 11]. Importantly, these recommendations hinge on the accuracy of the diagnosis. Distinguishing SCA from other potentially malignant forms of cystic neoplasm with certainty has been difficult. One study found that of 2622 cases of resected cystic neoplasm, 60% underwent surgical resection because of an unclear diagnosis [11]. Cross sectional imaging modalities have improved in resolution, but remain far from perfect in their ability to distinguish between subtypes of PCN: accuracy of identifying the subtype of PCN is reported to range from 40 to 81% for CT and 40 to 95% for MRI [3]. SCA is divided into morphologic patterns, with 70% of SCA exhibiting a microcystic pattern, in which the tumor is composed of numerous, small cysts [12]. The macrocystic pattern, by contrast, describes fewer large cysts, which can resemble MCN or IPMN [12]. Presence of intratumoral hemorrhage, as in our patient, also leads to difficulty in differentiation from solid tumors, as cross-sectional imaging can show heterogeneous enhancement from hemorrhage, necrosis, and cystic degeneration [12].
Endoscopic ultrasound (EUS) can provide supplemental information, especially if fine needle aspiration (FNA) is performed for fluid analysis. Cyst fluid carcinoembryonic antigen (CEA) level has been useful in differentiating between mucinous and non-mucinous pancreatic cysts [13]. Vascular endothelial growth factor (VEGF) has been identified as an accurate SCA biomarker [13]. Carr et al. found that combined CEA and VEGF cyst fluid levels had 95% sensitivity and 100% specificity for the diagnosis of SCA. These results are encouraging; however, EUS with FNA may not be technically feasible or yield sufficient aspirate for analysis for all patients.
Even when a clear diagnosis of SCA is made based on radiographic and clinical findings, different management strategies have been recommended. The European Study Group on cystic tumors of the pancreas recommend observation for 1 year for asymptomatic patients and symptom-based follow up past 1 year. The group recommends surgical resection for patients with symptoms related to compression of adjacent organs [3]. A single center study on SCA recommended offering surgical resection for symptomatic patients and for patients with SCA measuring ≥ 4 cm, as larger tumors were more likely to become symptomatic and were associated with faster growth rates [4]. When different types of cystic neoplasm, especially those harboring malignant potential such as MCN or IPMN, cannot be confidently excluded, invasive diagnostic modalities, or even resection, may be indicated [10].
Our case report describes a patient who developed spontaneous hemorrhage associated with previously diagnosed SCA. There have only been a few cases of hemorrhage related to SCA reported based on our literature search. In two case reports, patients presented with an acute abdomen from hemorrhage, and both patients underwent distal pancreatectomy of large cysts with diameter > 10 cm [7–8]. While rare, hemorrhage associated with SCA may be life threatening and requires prompt identification and surgical intervention.
Our case report is also unique because the final pathology was remarkable for three different types of neoplasm: macrocytic serous cystadenoma, main duct IPMN, and well-differentiated neuroendocrine tumor. SCAs have been found concurrently with other types of pancreatic tumors within the same excised specimen, such as IPMN, pancreatic ductal adenocarcinomas, neuroendocrine tumors and metastatic tumors. Based on our literature search, no prior cases of SCA with two different types of neoplasms have been reported. While mixed serous-neuroendocrine type of SCA have been reported, they represent a small portion of SCA. In a study of 193 pancreatic serous neoplasms, concurrent neoplasms were found in 13% (27) of cases [14]. Most commonly identified synchronous neoplasms were pancreatic neuroendocrine tumors (6%, 12/193) and IPMN (< 1% (1/193) [14]. Incidental PanIN was found in 83 cases. The possibility of SCA harboring other neoplasms with malignant potential should be considered in outlining a management plan.