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 are diagnosed incidentally on imaging studies, as up to 61% of patients are asymptomatic [11]. Risk of malignant transformation to cystadenocarcinoma is 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]. These recommendations hinge on the accuracy of the diagnosis. Distinguishing SCA from other potentially malignant forms of cystic neoplasm with certainty is difficult. One study found that of 2622 cases of resected cystic neoplasm, 60% underwent surgical resection because of uncertainty in diagnosis [11]. Even with improvements in the resolution of cross-sectional imaging modalities, the ability to distinguish between subtypes of PCN has been limited: the accuracy rate for identifying the subtype of PCN is reported to range from 40 to 81% for CT and 40 to 95% for MRI [3]. Certain morphologic patterns of SCA add to the complexity of diagnosis. While 70% of SCA exhibit a microcystic pattern, in which the tumor is composed of numerous, small cysts, some, by contrast, exhibit a macrocystic pattern, which describes fewer large cysts [12]. The macrocystic pattern can resemble MCN or IPMN on imaging [12]. The presence of an intratumoral hemorrhage, as in our patient, also leads to difficulty in differentiation between cystic and solid tumors, since 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. While these results are encouraging, EUS with FNA may not be technically feasible or may not 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 recommends observation for 1 year for asymptomatic patients followed by symptom-based follow up and surgical resection for patients with symptoms related to compression of adjacent organs [3]. Another single center study on SCA recommends offering surgical resection for symptomatic patients and for patients with SCA measuring ≥4 cm, as larger tumors are more likely to become symptomatic and to be associated with faster growth rates [4]. Invasive diagnostic modalities, even resection, are indicated when different types of cystic neoplasm, especially those harboring malignant potential such as MCN or IPMN, cannot be confidently excluded [10].
Our case report describes a patient who developed spontaneous hemorrhage associated with previously diagnosed SCA. Only a few cases of hemorrhage related to SCA have been reported based on our literature search. In two case reports, patients presented with acute abdomen from hemorrhage and underwent distal pancreatectomy of large cysts with a 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 remarkably identified three different types of neoplasm: macrocytic serous cystadenoma, main duct IPMN, and well-differentiated neuroendocrine tumor. SCAs have been found concurrently with one other type of pancreatic tumors within the same excised specimen, such as IPMN, pancreatic ductal adenocarcinomas, neuroendocrine tumors and metastatic tumors. 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 [14]. Based on our literature search, no prior cases of SCA with two different types of neoplasms have been reported. The possibility of SCA harboring other neoplasms with malignant potential should be considered in outlining a management plan.