Fig. 5.1
Serous cystadenoma. The delicate cells lining the fibrous septae are destroyed by the smearing process leaving behind acellular fibrous tissue fragments in a bloody background and leading to a nondiagnostic report. (Direct smear, hematoxylin and eosin)
Fig. 5.2
Serous cystadenoma. Liquid-based processing of FNAs of suspected serous cystadenomas increases the yield of intact cyst lining cells, which are polygonal, nonmucinous epithelial cells with bland round nuclei and even chromatin. (ThinPrep, Papanicolaou)
Fig. 5.3
Serous cystadenoma. The septae of serous cystadenomas are very vascular leading to frequent bleeding, and thus the presence of hemosiderin-laden macrophages in the smear background is not uncommon. While not diagnostic, their presence may act as a surrogate marker for this neoplasm. (Direct smear, Papanicolaou)
Fig. 5.4
Serous cystadenoma. Cellblock and small core biopsy fragments provide tissue architecture for a definitive diagnosis. (Core biopsy, hematoxylin and eosin)
Paucicellular to acellular specimens
Clear to bloody background
No extracellular mucin [except for occasional gastrointestinal (GI) contamination]
Uniform nonmucinous, cuboidal cells in small clusters that form a flat sheet or small groups
Round, central to slightly eccentric nuclei with a smooth nuclear contour, evenly dispersed chromatin and indistinct nucleolus.
Scant but visible granular to clear, sometimes finely vacuolated cytoplasm.
Absence of necrosis, atypia, or mitoses
PAS positivity with PAS-D negativity of the cytoplasm, confirming the glycogenic content
Neuroendocrine Microadenoma
Neuroendocrine microadenomas are also known as “islet cell tumorlets.” By definition, these are neuroendocrine neoplasms < 5 mm in greatest dimension and unassociated with a clinical syndrome due to hormonal secretion [1]. These lesions are increasingly recognized and sampled due to the increased use of cross-sectional imaging. A cytological diagnosis of neuroendocrine microadenoma requires correlation with imaging. It is recommended that a statement be placed in the cytology report indicating that the diagnosis is based on this correlation and that neuroendocrine tumors ≥ 5 mm have malignant potential .
Cytological Criteria: Neuroendocrine Microadenoma
Cytological features diagnostic of a neuroendocrine tumor (See Chap. 6) coupled with imaging size < 5 mm.
Lymphangioma
Lymphangiomas occur within the pancreatic parenchyma or peripancreatic soft tissue. This benign neoplasm represents < 0.2 % of pancreatic neoplasms.
Most patients are young women with a mean age of 29 years. The most common presentation is vague abdominal pain [9]. On imaging, tumors appear as large solitary or multicystic anechoic or hypoechoic mass lesions with no connection to the main pancreatic duct and no high-risk imaging features such as mural nodules. Aspiration procures non-mucoid, yellow, occasionally white, and watery cyst fluid [10]. Differentiation from other primary pancreatic cysts is important for patient management. CEA levels are low and CA 19.9 is not elevated. Amylase level may show mild elevation in the low thousands and thus may suggest the diagnosis of pseudocyst . The absence of the clinical history of pancreatitis as well as the absence of the typical grungy pseudocyst contents should preclude this misdiagnosis .
Cytological Criteria [10]: Lymphangioma (Fig. 5.5)
Fig. 5.5
Lymphangioma. Small mature lymphocytes in a relatively clean, nonmucinous background support the interpretation of lymphangioma. (Cytospin, Papanicolaou)
Numerous small mature appearing lymphocytes
No epithelial cells (barring GI contamination)
Nonmucinous background
Explanatory Notes
High-resolution cross-sectional imaging has increased the ability to recognize microcystic serous cystadenomas , particularly when they are associated with a stellate scar, thus precluding FNA for evaluation [11]. Generally serous cystadenomas that go to FNA are those that mimic primary mucinous cysts due to the presence of oligocystic or macrocystic locules. Some serous cystadenomas with small microcysts may appear solid on imaging leading to an FNA. Serous cystadenomas are frequently lobulated multicystic masses with very well-defined borders. Correlating the imaging and ancillary tests of cyst fluid analysis with cytology is critical to making a definitive diagnosis of serous cystadenoma in the absence of tissue fragments or core biopsy in a cellblock. Grossly, the cyst fluid is thin and bloody or thin and clear; never mucoid. Both the cyst fluid CEA and amylase should be low, < 5 ng/ml for CEA and < 250 U/L for amylase [5]. An FNA suggestive but not diagnostic of serous cystadenoma may be classified as negative rather than nondiagnostic.
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