Contributed by Sarah K Harm, MD and Alyssa M Krasinskas, MD
A 67 year old female presented with left upper quadrant abdominal pain. She had a strong family history of non-insulin dependent diabetes mellitus. Amylase, lipase, CA19-9, total bilirubin, direct bilirubin, and liver enzymes were within normal limits. Abdominal computed tomography (CT) imaging showed a hypodense, hypoenhancing 3.2 x 2.6 cm lesion in the body/tail of the pancreas. The mass encased the splenic artery but did not involve any other major vessels. There was no abdominal lymphadenopathy. She underwent an endoscopic ultrasound (EUS) with fine-needle aspiration (FNA) of the lesion. EUS demonstrated a focal mass encasing the splenic artery. Cytology was suspicious for malignancy. Given the presence of a mass, pain, and suspicious cytology, she underwent surgical exploration and removal of this lesion.
A distal pancreatectomy specimen was received containing a 4.5 x 2.5 x 1.5 cm firm, pink-white mass. Microscopically, sections of the lesion showed a chronic pancreatitis with a prominent lymphoplasmacytic inflammatory infiltrate (Figures 1, 2 and 3). The infiltrate involved the peripancreatic fat, surrounded the splenic artery and extended to the splenic vein (Figure 4). Smaller veins were also involved by an obliterative phlebitis (Figure 5). Multiple foci of pancreatic intraepithelial neoplasia (PanIN 1A-2) were identified. Immunohistochemical markers confirmed a mixed inflammatory infiltrate with a predominance of T-cells. Immunohistochemical staining for IgG4 showed positive staining in plasma cells, with >10 cells per high power field (Figure 6).