Fine-needle aspiration of intrapancreatic accessory spleen: cytomorphologic features and differential diagnosis.
BACKGROUND
Intrapancreatic accessory spleen (IPAS) is a rare benign lesion of the pancreas that frequently clinically and radiographically mimics a solid neoplasm. Very rarely, epidermoid cysts may form in IPAS and be mistaken for a cystic neoplasm of the pancreas on radiographic imaging. IPAS and epidermoid cyst involving intrapancreatic cyst (ECIPAS) are benign, and, if recognized, do not require surgical intervention. There are few reports of the cytopathologic features of IPAS diagnosed by fine-needle aspiration (FNA).


METHODS
Here we report a series of 6 cases of endoscopic ultrasound (EUS)-guided FNA of IPAS, 3 of which had histological confirmation, including 1 case of histologically confirmed ECIPAS.


RESULTS
Cytomorphologic features of IPAS include a polymorphous population of hematopoietic cells, including lymphocytes, eosinophils, histiocytes, plasma cells, and red blood cells, admixed with numerous small blood vessels representing splenic sinusoids. CD8 immunostaining of cell block or core biopsy material highlights splenic endothelial cells and confirms the diagnosis. FNA of ECIPAS reveals predominantly macrophages and proteinaceous debris.


CONCLUSIONS
Diagnostic pitfalls include pancreatic neuroendocrine tumor. If IPAS is recognized as a diagnostic consideration on EUS-FNA, unnecessary surgical resection may be avoided.
Department of Pathology, The Sol Goldman Pancreatic Cancer Research Center, The Johns Hopkins Hospital, Baltimore, Maryland 21287, USA. atatsas1@jhmi.edu
Armanda D
AD
Tatsas
Christopher L
CL
Owens
Momin T
MT
Siddiqui
Ralph H
RH
Hruban
Syed Z
SZ
Ali
D000368:Aged; D044963:Biopsy, Fine-Needle; D003937:Diagnosis, Differential; D004724:Endoscopy; D019160:Endosonography; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010190:Pancreatic Neoplasms / Q000175:diagnosis*; D011379:Prognosis; D013158:Splenic Diseases / Q000175:diagnosis*