A case of unresectable ectopic acinar cell carcinoma developed in the portal vein in complete response to FOLFIRINOX therapy.

A 56-year-old man presented to our hospital for close examination of a mass in the portal vein. CT showed a homogeneously enhanced mass occupying the portal vein. No other lesions suggestive of a primary tumor were detected. Endoscopic ultrasound-guided fine-needle aspiration revealed that the tumor was pathologically acinar cell carcinoma (ACC) based on the positive staining for both BCL-10 and trypsin. He was diagnosed with an ectopic ACC developed in the portal vein. Because the tumor invaded secondary branches of the right intrahepatic portal vein and the superior mesenteric vein, it was considered surgically un-resectable. Therefore, chemotherapy with gemcitabine plus nab-paclitaxel (GEM + nab-PTX) was started. After 2 courses, CT showed progressive disease, so the regimen was switched to FOLFIRINOX. After starting treatment with FOLFIRINOX, the tumor shrank gradually. After 29 courses, CT scan eventually showed disappearance of the tumor and complete response was achieved. After 34 courses, the chemotherapy was discontinued. Since then, the patient has been recurrence-free for 5 years. Our English literature review yielded 6 cases, including this case, of un-resectable ACC in which complete response was achieved by chemotherapy. Our case suggest that platinum-based regimen might be an effective therapy for un-resectable ACC, including ectopic ACC.