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

Abstract

Intrapancreatic and intraabdominal accessory spleens (IPIASs) are rarely encountered in endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) biopsies. However, as incidentally discovered IPIAS can mimic a benign or malignant pancreatic neoplasm on imaging studies, a definitive diagnosis made by EUS-FNA can avert an unnecessary surgical intervention or additional radiologic follow-up. We report five cases of intrapancreatic splenules and one case of accessory spleen (AS) in which a definitive diagnosis was made on EUS-FNA. Previously recognized FNA cytomorphologic features of splenic tissue, including ASs and splenosis, are endothelial cells and polymorphous lymphocytes admixed with neutrophils, eosinophils, plasma cells, histiocytes, and lymphoglandular bodies. We describe the additional finding of abundant large platelet aggregates as another distinguishing feature of splenic tissue on FNA. In all six cases, large platelet aggregates were identified along with polymorphous lymphoid cells, lymphoglandular bodies, loose aggregates of endothelial cells and scattered or aggregated bland spindle cells. A review of 10 consecutive cases of EUS-FNA-sampled benign intraabdominal lymph nodes showed that the presence of large platelet aggregates, three-dimensional aggregates of lymphoid cells and of bland slender spindle cells and the absence of follicular germinal cell components (tingible body macrophages and lymphohistiocytic aggregates) are useful in differentiating IPIASs from reactive lymph nodes. Immunoperoxidase stains were useful to confirm a suspected IPIASs by showing CD31-positive acellular flocculent material, consistent with large platelet aggregates and a rich CD8-positive endothelial cell network between CD45-positive lymphoid cells and CD68-positive histiocytes in all six cases.

Fine‐needle aspiration of intrapancreatic accessory spleen: Cytomorphologic features and differential diagnosis

“…In our series, we noted similar cytomorphology to those cases that have been reported previously,2‐4 including a mixed population of inflammatory cells present both embedded in a vascular meshwork and loosely dispersed throughout the aspirate smears. We did not observe the presence of large platelet aggregates, a feature that has been recently described in IPAS 19. Of the cases of surgically resected IPAS reported in the literature, the most common preoperative radiographic diagnosis is a nonfunctioning PanNET 10.…”

Intrapancreatic accessory spleen: a diagnostic dilemma

“…On FNA pathology, the red pulp is represented by numerous red blood cells, large platelet aggregates, endothelial cells, and stromal fragments whereas the white pulp is represented by polymorphous lymphoid cells, lymphoglandular bodies, and three-dimensional lymphoid aggregates. 39 Another predominant feature is the endothelial cells, positive for both CD8 40 and CD31 in cell block sections. However, FNA has a relatively low diagnosis efficacy and a high risk of misdiagnosis to p-net according to the current study ( Table 2).…”

Endoscopic ultrasound‐guided fine needle aspiration of accessory spleen: Cytomorphologic features and diagnostic considerations

“…We distinctively examined the detailed cytomorphologic features by reviewing the cytology slides and observed presence of polymorphous population of lymphocytes and mixed inflammatory cells including eosinophils and histiocytes. These cytologic features are well described in the literature, 11‐13 however, they are not specific. We found that the most useful cytologic features to support the diagnosis of AS are the presence of cohesive clusters of lymphoid cells, LPAs and prominent vasculature, which help distinct AS from lymph node sampling.…”