Pancreatic Head Mass: A Rare Manifestation of Granulomatosis With Polyangiitis

Abstract

A solid pancreatic mass is found to be malignant 95% of the time, while inflammation accounts for the remaining cases. We report a case of granulomatosis with polyangiitis (GPA) presenting as an inflammatory mass initially suspected to be metastatic pancreatic cancer. This is a 73-year-old male who presented to the ED with weakness, fevers, night sweats, and weight loss. His medical history was significant for severe chronic sinusitis and nasal polyps. On physical examination, he was noted to have bilateral lower extremity nodular purple plaques with necrotic centers. Laboratory studies were significant for leukocytosis, mildly elevated alkaline phosphatase, normal kidney function, transaminases and bilirubin. CT imaging demonstrated a low-attenuation mass in the pancreatic head along with multiple cavitary pulmonary nodules without hepatic lesions. Our differential diagnoses included metastatic pancreatic cancer versus an autoimmune process. CA 19-9 and CEA were within normal limits. An autoimmune work-up showed negative ANA, positive RF, elevated WSR, elevated IgE, and an elevated C-ANCA. Skin biopsy yielded leukocytoclastic vasculitis with granular fluorescence of C3 and IgG. Biopsy of lung nodules revealed extensive necrosis with acute neutrophilic infiltrates, fibrin thrombi, multinucleated giant cells, consistent with GPA. He was started on high dose steroids. He was discharged with plans for repeat imaging and biopsy of the pancreatic mass. A pancreatic mass in an elderly patient is highly concerning for cancer, which was our primary differential diagnosis. The absence of hepatic involvement and normal tumor markers decreased the likelihood of a primary pancreatic cancer with lung metastases. Due to his history of recurrent sinusitis, nasal polyps, and skin lesions, an autoimmune etiology was explored. A positive C-ANCA coupled with the lung biopsy findings established the diagnosis of GPA, a very rare cause of pancreatic masses. Most cases detailing GI manifestations of GPA present with pancreatitis or painless jaundice, but few have reported pancreatic masses. Necrotizing vasculidities 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 pancreatic cancer due to the significant differences in treatment and prognosis. More studies are needed to determine whether these pancreatic masses should be biopsied or followed with imaging.1406_A.tif Figure 1: ßLungßonstrating extensive necrosis with acute neutrophilic infiltrates, fibrin thrombi, and multinucleated giant cells.1406_B.tif Figure 2: Low attenuation mass anteriorly in the pancreatic head measuring approximately 2.0 cm. The margins of the mass are inseparable from posterior wall of the duodenal bulb.1406_C.tif Figure 3: Bilateral lower extremity lesions described as nodular purple plaques with necrotic centers.