A rare case of a pancreatic mass due to accessory spleen; when EUS-FNA is not enough

Abstract

A 56-year-old man was referred with asymptomatic elevation of pancreatic hydrolase levels. Magnetic resonance imaging (MRI) delineated a pancreatic lesion with a low T1 and high T2 signal (• " Fig. 1). Endoscopic ultrasound (EUS) found an oval, well-defined, isoechogenic, homogeneous mass in the pancreatic parenchyma, without any vascular invasion and no locoregional lymph nodes (• " Fig. 2). Fine-needle aspiration (FNA) showed small epithelioid cells. Immunostaining was positive for antichromogranin, antisynaptophysin, and anti-KI-67 (5 %), and a few cells were positive for anti-CD56. This was consistent with a neuroendocrine tumor (NET). Octreotide positron emission tomography combined with computed tomography (PET-CT) showed a focal uptake into the pancreas without any other nonphysiological uptake (• " Fig. 3). CA19-9 and chromogranin levels were normal. Caudal pancreatectomy with spleen preservation was performed. Histological examination found no proof of NET but did reveal an intrapancreatic accessory spleen (IPAS) (• " Fig. 4). The postoperative period and follow-up were satisfactory. Accessory spleens may be found in 15 % of the population but are rarely located in the pancreatic tail (17 %) [1]. Most IPASs have a homogeneous contrast-enhanced appearance on CT and MRI, sharing features with hypervascular lesions (such as NETs) [1]. Octreotide scans have a high sensitivity for detection of gastrointestinal NET (70 %-95 %). The somatostatin receptors on the surface of splenic lymphocytes may lead to false diagnosis of NET [2]. Nuclear scintigraphic investigations such as those with 99m

Intrapancreatic accessory spleen: a diagnostic dilemma

“…IPAS displayed a homogeneous, green elastographic pattern on EUS-elastography. 34 IPAS showed numerous thick white bands with floating small black particles inside the bands suggesting the presence of blood vessels and floating erythrocytes on EUS-guided needle-based probe confocal laser endomicroscopy (nCLE) which allows direct tissue architecture evaluation. 35 The diagnostic value of somatostatin receptor nuclear medicine examination (SRNME) is limited since both well-differentiated p-net and splenic tissue show intense uptake of somatostatin analogs because of the presence of somatostatin receptors on the surface of splenic lymphocytes.…”

Intrapancreatic Accessory Spleen: A Diagnosis Not to Forget!

“…As a well-defined homogeneous and hypervascular lesion, it is most frequently misdiagnosed as a pancreatic NET. Octreotide scan has a high sensitivity (70–95%) for the detection of gastrointestinal NET and can be useful in the differential diagnosis from this pancreatic neoplasm [8, 9]. However, false-positive results have been reported in IPAS.…”

“…Fortunately, this percentage is decreasing with the improved radiologic and endoscopic sampling diagnostic capabilities, in particular with EUS-FNA. EUS-FNA has been demonstrated to be a safe and effective tool to obtain a definitive IPAS diagnosis [1, 2, 7, 8, 9, 10, 11, 12, 13]. In the largest study of IPAS diagnosis established using EUS-FNA, this technique was successful in 90% of the cases, and no complications were reported [9].…”

Large platelet aggregates in endoscopic ultrasound‐guided fine‐needle aspiration of the pancreas and peripancreatic region: A clue for the diagnosis of intrapancreatic or accessory spleen

“…In addition to lymphoid cells, FNA samples of lymphoepithelial cysts characteristically show cyst fluid, cholesterol crystals and abundant, anucleated, keratinous debris and occasional nucleated squamous cells, 33 findings that are helpful differentiating features from IPAS. 35 Another case of IPAS was similarly diagnosed as PEN based on the presence of chromogranin, glucagon, gastrin and somatostatin staining of fortuitously sampled pancreatic islet cells. 34 Cytologic distinction from a PEN is usually straightforward, but occasionally pancreatic endocrine tumor cells may be difficult to distinguish from lymphoid cells, especially during ROSE.…”

“…However, it is essential to exclude fortuitous sampling of normal islet cells from the pancreatic parenchyma surrounding the tumor nodule, as demonstrated by a recently reported case in which an intrapancreatic AS that was brightly positive on octreotide PET/CT due to the presence of somatostatin receptors on splenic lymphocytes, was misdiagnosed as PEN on EUS-FNA based on the positivity of the aspirated cells with immunostains for chromogranin, synaptophysin, and CD56. 35 Another case of IPAS was similarly diagnosed as PEN based on the presence of chromogranin, glucagon, gastrin and somatostatin staining of fortuitously sampled pancreatic islet cells. 36 Aspirates of acinic-cell carcinomas may show abundant naked nuclei and may, therefore, superficially resemble a lymphoid aspirate.…”