A 36-year-old woman presented for evaluation of a pancreatic mass that had been discovered via computed tomography (CT). The patient had a 25-year history of ulcerative colitis (UC) complicated by primary sclerosing cholangitis. Significant medical history also included a total proctocolectomy performed 3 years earlier for treatment of a poorly differentiated adenocarcinoma (T1N0M0). Due to the presence of negative margins and the absence of lymphatic, venous, or perineural invasion, the patient had not undergone adjuvant chemotherapy.
The patient's current presentation was characterized by an insidious onset of epigastric pain that radiated to her back over the previous 3 months. On examination, left upper quadrant tenderness and epigastric fullness were noted without a palpable mass. CT revealed a large, bilobed, hypodense, infiltrating mass lesion in the neck of the pancreas and possibly 2 separate lesions measuring approximately 2.7 cm × 1.9 cm and 3.2 cm × 2.1 cm, respectively, that completely encased the superior mesenteric vein, left renal vein, and superior mesenteric artery (Figure 1). The patient's carcinoembryonic antigen level measured 7 ng/mL (normal, 0–3 ng/mL), and her CA 19-9 level measured 1,022 U/mL (normal, <37 U/mL). She was referred for endoscopic ultrasound (EUS) to obtain more definitive imaging and tissue diagnosis via EUS-guided fine-needle aspiration (FNA). EUS revealed multiple lymph nodes (up to 12 mm in size) in the peripancreatic space and 2 distinct lesions within the pancreas: a 30-mm heterogeneous mass in the pancreatic neck and a 35-mm hypoechoic mass within the body of the pancreas (Figure 2). Direct smears prepared from FNA samples of the peripancreatic node revealed only normal lymphoid cells; surprisingly, samples of the body and the neck of the pancreas were positive for squamous-cell carcinoma (Figure 3). Combined fluoro-2-deoxy-D-glucose (FDG) positron emission tomography (PET)/CT imaging demonstrated an intense FDG uptake corresponding to the pancreatic mass lesions (Figure 4). Metastasis to the retroperitoneal lymph nodes and the left supraclavicular node was suggested by moderate and intense FDG-avid activity, respectively. Repeat core biopsies of the pancreas revealed squamous-cell carcinoma with cytoplasmic keratinization and marked nuclear atypia (Figure 5). Immunohistochemical staining revealed that the tumor was strongly positive for CK5/6 and p16 but negative for CK7 and CK20. In situ hybridization testing for human papillomavirus was negative.
Due to the rarity of pancreatic squamous-cell carcinoma, slides from the patient's earlier total colectomy specimen were pulled and reviewed. Interestingly, foci within that tumor were suggestive of the squamous differentiation found in the pancreatic tumor (Figure 6). Additionally, the colonic malignancy was positive for p16 and negative for high-risk human papillomavirus. Given the low incidence of primary pancreatic squamous-cell carcinoma and the similar immunophenotype of the 2 tumors, the patient was thought to most likely have pancreatic metastasis from a primary colonic lesion, rather than a de novo lesion. At the time of this case report's submission, the patient had completed 2 cycles of palliative chemotherapy involving gemcitabine hydrochloride (Gemzar, Lilly), docetaxel (Taxotere, Sanofi Aventis), and capecitabine (Xeloda, Hoffmann La Roche), and her most recent CA 19-9 measurement was 29 U/mL.