IgG4-Related Focal Autoimmune Pancreatitis and Küttner’s Tumour

Abstract

Introduction: Type 1 autoimmune pancreatitis (AIP) or chronic sclerosing sialadenitis (Küttner’s tumour) is an uncommon disorder that has recently been confirmed as an IgG4-related disease (IgG4-RD). Here, we report a rare case of a patient with IgG4-related focal type of AIP (f-AIP) accompanied with Küttner’s tumour manifesting itself as a mass in the neck and several lumps in the lower lip, which was originally misdiagnosed of being PC with neck metastasis. Methods: A 53-year-old male from northeast China was admitted for abdominal distension and diarrhea lasting for 4 years. He presented a painless, hard left neck mass with slight dysfunction of salivary secretion and a 20-pound weight loss over 6 months. One year prior to admission, CT imaging identified a possible pancreatic body carcinoma resulting in surgical resection of the pancreatic body and tail with en-bloc splenectomy at that time. The patient denied any history of alcohol, tobacco, or illicit drug use. On examination, several firm 0.3-cm non-tender lumps were seen in the mucosa of his lower lip. He also had a painless, hard, fixed mass in the left submandibular area (suspected cervical metastasis). Abdominal examination revealed mild epigastric tenderness to deep palpation without rebound. The laboratory test data on admission revealed high levels of IgG4 (32.7 g/L) and positive reaction with anti-nuclei antibody. An ultrasound scan of the neck showed left swollen submandibular gland (4.2 cm length × 2.8 cm width × 2.1 cm height), suggesting the possibility of chronic sialadenitis. An enhanced CT scan of the abdomen revealed a relatively low density of the pancreatic head as well as extra- and intrahepatic bile duct dilatation, suggesting the possibility of pancreatic head cancer. The patient underwent labial gland lumps resection and an ultrasound-guided biopsy of the left neck mass. He was diagnosed with IgG4-related f-AIP and Küttner’s tumour on the basis of numerous IgG4-positive plasma cells in excisional pancreatic body mass sample and labial gland specimen. The patient responded well to corticosteroid therapy and remains healthy, with no signs of recurrence at 1-year follow-up. Conclusion: IgG4-RD is a recently recognized multi-organ fibro-inflammatory condition with a propensity to manifest itself as a mass-forming lesion characterized by the presence of abundant IgG4+ plasma cells, elevation of serum IgG4 levels, and a dramatic steroid responsiveness. Since the differentiation of f-AIP from PC is very difficult and their treatment and prognosis are quite different, we suggest that AIP should always be considered in case of a focal pancreatic mass.