A solid pancreatic mass is malignant 88%–95% of the time.1,2 The remaining cases include a variety of inflammatory masses that may mimic malignancy. Granulomatosis with polyangiitis (GPA) is a rare cause of an inflammatory mass that is particularly difficult to diagnose without other systemic manifestations. We report a case of GPA presenting as an inflammatory pancreatic mass that was initially suspected to be metastatic pancreatic cancer. We take the opportunity to provide a review of the literature on similar presentations and discuss the management of suspected cases.
A 73-year-old man presented to the emergency department with a three-month history of generalized weakness, fevers, weight loss, and maxillary sinus pain. His medical history was significant for chronic sinusitis and recurrent nasal polyps since childhood. He also described a history of lower extremity rashes that usually self-resolved. He denied any history of cigarette smoking, alcohol use, recent travel, sick contacts, or significant family history. His vital signs were normal on admission. Physical examination revealed 2–3 cm nodular purple plaques with necrotic centers (Figure 1). Pertinent negative findings included no evidence of jaundice, abdominal tenderness, distention, or palpable masses. His laboratory studies were significant for leukocytosis of 20 k/μL, mildly elevated alkaline phosphatase at 148 U/L, normal kidney function, normal transaminases, and normal bilirubin.
Abdominal computed tomography (CT) demonstrated a low-attenuation mass in the pancreatic head measuring 2.0 cm in diameter, which appeared inseparable from the posterior wall of the duodenal bulb and the medial wall of the duodenal sweep (Figure 2). In addition, thoracic CT revealed multiple bilateral necrotic and cavitary pulmonary nodules ranging from 1.6 to 5 cm in diameter (Figure 3). There was no evidence of hepatic involvement per CT imaging. Given the patient's age, sex, symptoms, and imaging findings, our initial diagnostic impression was pancreatic cancer. Carbohydrate antigen 19-9 and carcinoembryonic antigen were within normal limits. Thus, an autoimmune workup was performed which revealed negative antinuclear antibody, normal IgG4 levels, positive rheumatoid factor, elevated erythrocyte sedimentation rate, elevated immunoglobulin E levels, and elevated cytoplasmic antineutrophil cytoplasmic antibodies. Skin biopsy yielded leukocytoclastic vasculitis with granular fluorescence of C3 and immunoglobulin G. Biopsy of lung nodules revealed extensive necrosis with acute neutrophilic infiltrates, fibrin thrombi, and multinucleated giant cells without the formation of granulomas (Figure 4).
The patient was diagnosed with GPA and treated with intravenous methylprednisolone 80 mg for 3 days, followed by prednisone 60 mg, and immunosuppression with rituximab. He was discharged with plans for a repeat imaging and possible endoscopic ultrasound (EUS) with a fine-needle aspiration of the pancreatic mass if no significant improvement with immunosuppression. After 2 months of treatment, repeat thoracic CT demonstrated regression of majority of the lung masses. Magnetic resonance imaging of the pancreas obtained 5 months after completion of immunosuppressive therapy demonstrated no evidence of a pancreatic mass (Figure 5).
This case demonstrates a very rare cause of a solid pancreatic mass. To our knowledge, there are only 8 previously reported cases of pancreatic masses caused by GPA.3–9 In all previous cases, primary pancreatic adenocarcinoma was the initial diagnostic impression. Our patient's presentation was very concerning for pancreatic cancer, given his advanced age, male gender, symptoms, weight loss, and imaging findings.10,11 Pancreatic adenocarcinoma is located in the head of the pancreas in 60%–70% of cases, and most are hypoattenuating on contrast abdominal CT.12 However, the absence of cholestatic hyperbilirubinemia, biliary dilation, pancreatic dilation, and a normal CA 19-9 rose suspicion of an alternative diagnosis.13
Owing to the patient's history of recurrent sinusitis, nasal polyps, and skin lesions, an autoimmune etiology was explored. The differential diagnosis included autoimmune pancreatitis (AIP); however, serum IgG4 levels were normal, and imaging was not characteristic of the “sausage-shaped” pancreas classically described in AIP. Although type-2 AIP is typically serum IgG4 negative, it is also generally associated with younger age of onset and the presence of chronic inflammatory bowel disease, which this patient did not have. A positive cytoplasmic antineutrophil cytoplasmic antibodies coupled with the lung and skin biopsy findings established the diagnosis of GPA, a very rare cause of pancreatic masses. A multidisciplinary team was involved in the decision to forego obtaining a confirmatory biopsy by EUS because of the high clinical suspicion for GPA. Instead, a less aggressive approach was taken by monitoring symptoms and obtaining follow-up imaging after a significant trial of immunosuppressive therapy. The resolution of the pancreatic mass on magnetic resonance imaging and improvement in other signs and symptoms after immunosuppressive therapy confirmed our diagnosis (Figure 6).14 Most cases detailing gastrointestinal manifestations of GPA present with pancreatitis, pancreatic insufficiency,15 or painless jaundice, but very few have reported pancreatic masses.
A literature review between 1992 and 2014 found 8 cases detailing inflammatory pancreatic masses due to GPA. A complete description of the previous 8 cases can be found in Table 1. The mean age of the patients was 61 years old, and 6 of 8 were women. Five patients presented with abdominal pain, whereas 3 presented with painless jaundice. Half of them had anti-PR3 positivity, whereas 2 had anti-myeloperoxidase antibodies. Systemic manifestations were found in 6 patients and included morning stiffness, lung masses, biliary obstruction, phlebothrombosis, sinusitis, and orchitis. In each case, the mass was initially thought to be primary pancreatic adenocarcinoma. EUS-guided biopsy was performed in one patient and was found to be negative for malignant cells. Six of 8 patients underwent pancreatectomy, whereas 2 patients received only medical treatment with resolution of symptoms. All patients achieved full recovery, and those receiving immunosuppressants remained asymptomatic.
Necrotizing vasculitides can mimic pancreatic carcinoma and should be considered in the differential diagnosis of atypical cases. It is important to distinguish a pancreatic mass caused by GPA from malignancy because of the significant differences in treatment and overall prognosis. Given the high mortality rates of pancreatic adenocarcinoma, it is not unreasonable for these patients to undergo surgical resection; however, pancreatectomies also entail high intraoperative risks.3,16 In this case, our team was able to diagnose and successfully treat the patient without adding an additional risk of developing complications from interventions such as EUS-guided biopsy or pancreatectomy. More studies are needed to determine whether these pancreatic masses, with lower suspicion for malignancy, should be biopsied or followed with imaging.
Author contributions: M. Castillo, A. Gonzalez, A. Ur Rahman, J. Kaur, V. Wadhwa, A. Schneider, and R. Pimentel wrote the manuscript and approved the final version. P. Bejarano provided the images and approved the final version. M. Castillo is the article guarantor.
Acknowledgments: The authors would like to acknowledge Albert Parlade for providing the radiological images.
Financial disclosure: None to report.
Previous presentation: This case was presented at the American College of Gastroenterology Annual Scientific Meeting; October 5–10, 2018; Philadelphia, Pennsylvania.
Informed consent was obtained for this case report.
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