Contributed by Chris Gilbert, MD and Scott Kulich, MD.
The patient is a 61 year-old male with a history of colitis who presented to the emergency department after sustaining abdominal trauma secondary to falling. As part of his workup, the patient underwent a CT scan which revealed a non-contrast enhancing low attenuation focus within the uncinate process of the pancreatic head measuring 2.5 x 2.3 cm. The patient subsequently underwent an endoscopic ultrasound which revealed an oval 33mm by 21mm well demarcated mixed solid and cystic mass with 2 hyperechoic foci seen in the head of the pancreas. The lesion was extensively sampled with a 25g needle for cytologic evaluation.
Intraprocedural evaluation of Diff-Quick stained slides (figures 1 and 2) was performed. The specimen was considered adequate for evaluation but a diagnosis was deferred pending the evaluation of Pap-stained smears (figures 3 and 4) and H&E stained cell block material (figure 5).
Based upon the cytologic findings, a Whipple procedure was performed.
On gross examination, the Whipple specimen consisted of the head of the pancreas, segment of duodenum, distal stomach, cystic duct and gallbladder. The posterior aspect of the specimen was notable for a rubbery, 2.7 x 2.5 x 2.3 cm completely encapsulated mass which was 1.8 cm from the nearest margin. The cut surface was partially cystic with the remaining areas consisting of solid pale, yellow-brown and tan-white tissue with focal areas of hemorrhage. (figure 6).
Multiple histological sections reveal the identity of the mass. It is a spindle cell lesion, associated with a nerve, with hypercellular (figure 7) and hypocellular (figure 8) areas. The tumor is well encapsulated and separated from the surrounding pancreas (figure 9). Cystic areas of degeneration are also present (figure 10).
CD117, Melan A, Pan Keratin, Neurofilament, HMB 45, Actin, and S100 immunohistochemical stains were performed to characterize the lesion. S100 (figure 11) diffusely and strongly stains the spindle cells. Actin (figure 12) strongly stains the capsule. Neurofilament highlights an extracapsular nerve (figure 13). The stains not shown were interpreted as negative.