Performance characteristics of molecular (DNA) analysis for the diagnosis of mucinous pancreatic cysts.

BACKGROUND: Diagnosis of mucinous pancreatic cysts (MPCs) is challenging due to the poor sensitivity of cytology provided by EUS-guided-FNA (EUS-FNA). OBJECTIVE: To quantify the test characteristics of molecular (DNA) analysis in suspected low-risk MPCs. DESIGN: A prospective cohort study performed in between 2008 and 2011. SETTING: Academic referral center. PATIENTS: Consecutive patients who underwent EUS-FNA of suspected MPCs. INTERVENTION: EUS-FNA and molecular (DNA) analysis of cyst fluid. MAIN OUTCOME MEASUREMENTS: The sensitivity and specificity of molecular analysis in the diagnosis of MPCs using the criterion standard of surgical pathology in resected cysts. RESULTS: Patients with suspected MPCs underwent EUS-FNA and cyst fluid DNA analysis. Surgical resection was performed in 48 patients (17%), confirming a mucinous pathology in 38 (79%). In this group, molecular analysis had a sensitivity of 50% and a specificity of 80% in identifying MPCs (accuracy of 56.3%). The combination of molecular analysis with cyst fluid carcinoembryonic antigen (CEA) and cytology resulted in higher MPC diagnostic performance than either one of its individual components, with a sensitivity, specificity, and accuracy of 73.7%, 70%, and 72.9%, respectively. There was no significant difference in accuracy between molecular analysis and CEA/cytology in this group. LIMITATIONS: Single-center experience. CONCLUSION: Molecular analysis aids in the diagnosis of MPCs when cytology is nondiagnostic or cyst fluid is insufficient for CEA or its level is indeterminate. Our results do not support the routine use of molecular analysis, which should be used selectively after review of imaging findings and cyst fluid studies. Further studies are needed to assess DNA's performance in malignant cysts.

Nearly Fatal Case of Whipple's Disease in a Patient Mistakenly on Anti-TNF Therapy.

Whipple's disease is a rare cause of chronic diarrhea and abdominal pain that may be confused with inflammatory bowel disease. We report a Whipple's case misdiagnosed as Crohn's disease in which treatment with anti-tumor necrosis factor (anti-TNF) therapy led to nearly fatal progression. Lymph node tissue obtained during laparotomy for suspected bowel necrosis stained dramatically with periodic acid-Schiff (PAS), and electron microscopy showed a bacterium consistent with Trophyrema whipplei. The patient made a remarkable recovery complicated only by cholestatic hepatitis, which was likely a treatment-associated inflammatory response. This case serves as a reminder that all granulomatous infections should be considered prior to initiation of anti-TNF therapies.