Intrapancreatic accessory spleen. Report of four cases diagnosed by ultrasound-guided fine-needle aspiration biopsy.

Intrapancreatic accessory spleen (IPAS) is a congenital anomaly usually misdiagnosed as a pancreatic neoplasm. For five years and four months, we collected seven IPASs located in the tail of the pancreas in four patients diagnosed by endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA). All cases had associated cell block preparations. Each patient underwent endoscopic ultrasound, computed tomography (CT), and magnetic resonance imaging (MRI) studies. The patients ranged in age from 57 to 73 years (mean age 65.7 years old). All lesions were well-defined, 1-1.9 cm in size (mean 1.5 cm). To our knowledge, a case with four IPASs in the tail of the gland has not been previously reported. Cytological features of IPAS included a polymorphous population of hematopoietic cells admixed with occasional blood vessels. Cell blocks comprised spleen red pulp. CD8 immunostaining of cell blocks highlighted splenic endothelial cells and confirmed the diagnosis. IPAS presented as an asymptomatic lesion detected on imaging studies. It may mimic a pancreatic neoplasm, mainly a neuroendocrine tumor. The use of EUS-FNA is an essential tool in the diagnosis of the lesion. The endothelial cells of the splenic sinuses characterized by their positivity for CD8 are evident in the sections of the cell blocks. This staining is considered specific and can be used as a confirmatory marker. EUS-FNA biopsy provides a reliable diagnosis that prevents unnecessary surgery.