P1516 - Chameleonic Chloroma: A Case of Myeloid Sarcoma Presenting as a Pancreatic Head Mass

Benjamin F. Cardenas, MD, Ayeetin M. Azah, MD, MBA, Azfar S.. Syed, DO, MBA, Jeffrey Laczek, MD
Walter Reed National Military Medical Center, Bethesda, MD

Introduction: Myeloid sarcoma (MS), or chloroma, is a rare form of acute myeloid leukemia (AML) occurring in less than 1% of AML cases. MS manifests as a mass in many extramedullary sites, with less than 8 cases in literature showing pancreatic involvement in patients without preexisting hematological malignancy. Its variable clinical presentation and overall rarity make diagnosis challenging. Here we present a case of pancreatic MS with the radiographic appearance of pancreatic ductal adenocarcinoma (PDAC).

Case Description/Methods: A 35-year-old male with an unremarkable medical history presented with one week of worsening epigastric pain and pale, watery stools. Physical examination was notable for scleral icterus and labs showed a cholestatic liver injury pattern. Abdominal ultrasound was unremarkable, but magnetic resonance cholangiopancreatography demonstrated a large obstructive hypo-enhancing pancreatic head mass with a double duct sign. Endoscopic ultrasound (EUS) showed a large hypoechoic mass immediately adjacent to the head of the pancreas and fine needle aspiration (FNA) demonstrated lymphatic tissue. A repeat EUS and FNA had similar findings. A dedicated pancreatic CT scan showed a pancreatic head mass with new omental caking and peripancreatic lymphadenopathy. Upper endoscopy and colonoscopy were performed to evaluate additional sites to biopsy and revealed what appeared to be a large subepithelial mass on the lesser curvature of the stomach; biopsies were interpreted as possible lymphoma. Bone marrow biopsy was obtained and revealed a high-grade myeloid neoplasm, with 16% blasts leading to a diagnosis of AML. Induction chemotherapy was started approximately two months after initial presentation. The patient has had a favorable response to chemotherapy and is in the process of finding a donor for allogeneic stem cell transplant.

Discussion: Myleoid Sarcoma (MS) should be considered alongside (PDAC) in the differential of pancreatic head masses, particularly in younger patients, when disease progresses more rapidly than expected for PDAC, or when FNA of a pancreatic mass shows lymphoid tissue. Historically, misdiagnosis of MS approached 75%, albeit it is decreasing due to newer technology. Gastroenterologists should be aware of this rare disease and be willing to perform repeat diagnostic testing or obtain tissue sampling outside of the normal biopsy methods for PDAC.


Disclosures:


Benjamin F. Cardenas, MD, Ayeetin M. Azah, MD, MBA, Azfar S.. Syed, DO, MBA, Jeffrey Laczek, MD. P1516 - Chameleonic Chloroma: A Case of Myeloid Sarcoma Presenting as a Pancreatic Head Mass, ACG 2023 Annual Scientific Meeting Abstracts. Vancouver, BC, Canada: American College of Gastroenterology.