From indeterminate to septic, the rapid transformation of a pancreatic lesion. Pancreatic cystic lesions, PCLs, can affect up to 20% of people above the age of 60 years. There are three major subtypes of PCLs, which are pseudocyst, neomycenocystic lesions, and mycenocystic lesions. Mycenocysts mainly include IPMN and mycenocystic neoplasms, which have a higher risk for malignant transformation. As a result, accurate distinction between neoplastic and benign pancreatic cyst is critically important. Current guidelines recommend EUSFNA for PCLs that meet specific criteria, two of them being lesions over three centimeters in diameter or suspected mass lesion. However, data is conflicting on the role of prophylactic antibiotics after EUSFNA, as only ASGE suggests its use, albeit with low clinical evidence. We present two cases of undifferentiated pancreatic lesions evaluated with EUSFNA or FMB that subsequently became septic, requiring EUS-guided intervention. Case one is a 65-year-old male who presented initially with four weeks of abdominal pain, nausea, a 10-pound weight loss, and chronic leukocytosis to 20. Two months prior, workup for the leukocytosis at an outside facility was unremarkable, except for a pancreatic head lesion measuring 5 by 2.9 centimeters on MRI. EUSFNA was performed on the lesion at an outside facility for further evaluation, and cytology revealed benign pancreatic tissue. However, serologic workup showed an elevated CA19-9 level of 59, raising concern for a pancreatic neoplasm. During representation to the hospital, repeat CT scans showed increased lesion to 7.1 by 6.5 centimeter, with pancreatic duct prominence and peripancreatic stranding. Significant labs include normal lipase of 60 and elevated WBC of 20. Given the increased size of the lesion and the initial non-diagnostic EUSFNA, we opted to perform a repeat diagnostic EUSFNA for the first time at our institution. It showed a 7.6 by 6 centimeter pancreatic head heterogeneous lesion of mixed echogenicity, suggestive of a cyst with internal debris. No antibiotics was given post-procedure. Histology result was unremarkable, and next-generation sequencing was negative for malignancy. Samples were sent for CEA and amylase, but they were insufficient. Three days post-procedure, he became septic. Blood and uric cultures were obtained. He was studied on breast spectrum antibiotics. However, despite that, his clinical course worsened. CTA of the abdomen and pelvis was performed, and it showed re-demonstration of the complex mock-diloculated lesion, measuring 8 by 6.4 centimeters in the pancreatic head, with multiple foci of air within the lesion indicated by the arrows, as well as acute thrombosis of the intra- and extra-hepatic portovenous structures marked by the yellow arrow, extending into the superior mesenteric vein marked by the red arrow, due to underlying stenosis caused by the pancreatic lesion. He was studied on heparin for portovenous thrombosis. Differential diagnoses include inflammatory cyst with debris versus lymphopathylesis or occult pancreatic neoplasm. Given the patient's worsening clinical condition, there was a high suspicion for an infected lymphothelial cyst. Therefore, a decision was made to drain the lesion using EUS-guided cystoduodenostomy and necrosectomy. Here, we see the cyst on EUS imaging measuring 6.9 by 5.9 centimeters. A 15 by 15 millimeter aluminum posing metal stent was deployed, with the phalanges in close approximation to the walls of the cyst and duodenum. The collection contained pus and white-colored material. The lymph was dilated. Necrosectomy was performed with a snare, and the wall of the cyst was biopsied for histology. Initial blood cultures grew gram-positive and multiple gram-negative bacteria. However, repeat cultures were negative. His antibiotics were transitioned to ceftriaxone and metronidazole. Histology results from the procedure revealed keratinized squamous epithelium with underlying lymphocytes, diagnostic for lymphothelial cyst, LEC, as seen here. The patient became vitally stable, leukocytosis improved, and he was tolerating regular diet. He was discharged on oral anticoagulation and antibiotics. VPCT scanned 4 weeks post-procedure showed patent lamps and decreased size of the pancreatic cyst to 4.5 by 20.8 centimeters. It remained asymptomatic, and the lamps was removed 2 weeks later. Case 2 is a 53-year-old male who presented after an incidental finding of a 5 centimeter pancreatic lesion concerning for pancreatic adenocarcinoma on a CT scan. Lab work was insignificant other than mild elevation in liver enzymes. An MRI was performed for better characterization of the lesion. It showed a 7.3 by 4 centimeters, non-enhancing on-site lesion without internal septation, pancreatic ovulary duct dilation. Due to the finding, an EUSFMB was performed. It showed a non-invasive round hypoechoic mass, as seen on the left. Antibiotic was started the day of the procedure and continued for 5 days post-procedure. Estology results revealed very rare benign epithelial cells. At 1 month follow-up, it reported persistent abdominal discomfort since the procedure that severely worsened within the past week, refractory to pain meds, and associated with decreased oral intake. He was told to come to the ED for the evaluation of his abdominal pain. Repeat CT scans showed a pancreatic lesion measuring 7.6 by 8.9 centimeters with some inflammatory stranding, which has increased in size from previous MRI. Lipids level was normal. Due to severe abdominal pain and elevated WBCF14, there was concern for an infected lesion. A decision was made to perform EUS guided intervention. During the procedure, the lesion was noted to be a cyst on EUS imaging that was partially filled with pus that was pasty and adherent to the cyst wall, as seen here. One day post-procedure, he had improvements in abdominal discomfort and oral intake. It was discharged with antibiotics. Two weeks post-discharge, patient reported near resolution of his abdominal discomfort. Estology report from the EUS procedure that included cyst wall biopsy showed LEC similar to the first case. One month post-procedure, CT scan showed decreased volume of the pancreatic cyst to 3.1 by 2.6 centimeters with reduction in periprancreatic inflammation. He was asymptomatic, was tolerating oral intake. One month later, the LAMPS was removed. Both these cases demonstrate likely infectious sequelae after EUS FNA or FNB investigation of undifferentiated pancreatic lesion, ultimately lymphobutylial cyst. Both patients developed sepsis, one with and one without prophylactic antibiotics, post-EUS sampling, highlighting the high infection rates in lymphobutylic cyst cases. When LEC is suspected, EUS sampling should be approached cautiously with a low threshold for prophylactic antibiotics, though sepsis may still occur as shown in our cases. If histology from EUS sampling shows LEC or LEC is suspected, patients should be monitored closely for the next 46 weeks for signs and symptoms of infection or sepsis. When infected, lymphobutylic cyst can be managed successfully with EUS guided transmural drainage and deridement. To our knowledge, only one published case describes such intervention in which an LEC was spontaneously infected prior to instrumentation, again highlighting the high risk of infection of this lesion. In conclusion, lymphobutylial cysts are difficult to diagnose without histological evidence, often through FNA or FNB. They can mimic malignant lesion with elevation in CA19-9 and CEA, and can become infected through instrumentation or spontaneously. While current guidelines do not strongly recommend prophylactic antibiotics after EUS FNA or FNB, it is not an uncommon practice. Close follow-up and care should be employed in cases diagnostic or suspected LEC for at least 4-6 weeks post-intervention.

pancreatic cystic lesions

EUSFNA

lymphoepithelial cysts

antibiotic prophylaxis

transmural drainage