Thrombotic thrombocytopenic purpura (TTP) is caused by the deficiency of ADAMTS13, a von Willebrand factor cleaving protease, which results in thrombotic microangiopathy. It is characterized by microangiopathic hemolytic anemia, thrombocytopenia, and microvascular thrombosis leading to organ damage. It has an extremely high mortality rate if left untreated, making early diagnosis and treatment of the utmost importance. We report a case of TTP that developed after vaccination with Ad26.COV2.S COVID vaccine.We present a case of a 50-year-old African American female who presented with dyspnea one week after receiving the first dose of Ad26.COV2.S vaccine. Initial labs showed anemia, thrombocytopenia, and markers of intravascular hemolysis. The suspicion for thrombotic thrombocytopenic syndromes (TTS), vaccine-induced thrombotic thrombocytopenia (VITT), TTP, and Immune thrombocytopenic purpura (ITP) was high based on the history and laboratory results. Computed tomography (CT) of the chest and ultrasound of bilateral lower extremities did not show any evidence of thrombosis. The absence of thrombosis in the presence of a high PLASMIC score increased the suspicion of TTP over the other differentials. Diagnosis of TTP was confirmed when the ADAMTS13 level was low with an elevated autoantibody inhibitor level. The patient underwent treatment with corticosteroids, plasmapheresis, and rituximab with improvement in symptoms and platelet count. TTP and VITT are the possible differential diagnosis for a patient presenting with anemia, thrombocytopenia, and signs of hemolysis after vaccination with Ad26.COV2.S. It is necessary to differentiate these two clinical entities as the management varies based on the diagnosis.

Localized necrotizing granulomatous lymphadenitis (GLA) is a very rare presentation of herpes simplex virus (HSV) infection. We are reporting a case that required multidisciplinary expertise to confirm the diagnosis and effectively treat the patient. Our patient had a recent diagnosis of chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL) and presented with hematuria and palpable inguinal lymph nodes. Affirmative diagnosis required a core biopsy of the lymph node with immunochemistry staining and polymerase chain reaction (PCR) testing. This case reviews the unusual presentation of an HSV infection and emphasizes the importance of maintaining a high index of suspicion for infection when treating an immunocompromised patient with persistent symptoms.

Figure 1. A. Abdominal CT revealed pneumobila, air within the biliary tree (red arrow). Pneumobilia is most often found after iatrogenic biliary tract manipulation and rarely in emphysematous cholecystitis and biliary-enteric fistulas. However, gas-forming bacteria in cholangitis can also cause pneumobilia, as in our case. B. ERCP revealed large periampullary duodenal diverticulum (dotted Black arrow). C. Removal of brown pigmented stone from ampulla of Vater.

Case Description/Methods: A 75-year-old male in the medical intensive care unit (ICU) developed painless massive hematochezia. The patient was initially admitted after being found down and had a complicated hospital course. At the time of consultation, large clots per rectum were reported, which subsequently converted to bright red bleeding. The day before GI evaluation, the patient's blood pressures were hypertensive to 155/66 mmHg, but subsequently dropped significantly to 81/43 mmHg. The rectal examination demonstrated a significant amount of bright red blood. Laboratory results showed a hemoglobin drop from 13.8 g/dL to 8.4 g/dL over four days despite four units of packed red blood cells transfused in-between. Computed tomography angiogram suggested contrast pooling/bleeding, with no definite source identified (Figure 1). The colonoscopy demonstrated extensive diverticulosis without any signs of active bleeding. On examination of the rectum, a blood clot with a small visible point of mucosal attachment was noted without any apparent ulcerations or erosions of the surrounding mucosa (Figure 2a and b). Epinephrine was injected at the periphery of the blood clot, which was subsequently removed with a snare, and revealed a raised nipple-like artery suggestive of a rectal Dieulafoy's lesion (Figure 3a). A hemostatic clip was placed as a secondary modality for hemostasis (Figure 3b). The patient was observed in the ICU and remained hemodynamically stable. He had no further episodes of hematochezia and no re-bleeding. Discussion: Dieulafoy's lesions are a rare but important cause of GI bleeding due to the severity of bleeding it often induces if left untreated. They are most commonly found in the stomach and the esophagus but can rarely present in the rectum. Due to the intermittent nature of the bleeding and the minimal mucosal defect, diagnostic evaluations remain limited. Our case demonstrates a classic endoscopic appearance of rectal DLs, which requires careful inspection during withdrawal. Once identified, these lesions can be successfully treated with two modalities of hemostasis.[2640] Figure 1. Arterial phase imaging demonstrating increased density material within the rectum (demarcated by green arrow), suggestive of contrast pooling/bleed. No definite source was identified. (a and b) Adherent blood clot with a point of mucosal attachment. (a) Successful removal of adherent clot after hemostasis with epinephrine injection (4 ml of 1:10000). (b) Successful placement of a hemostatic clip.

e18698 Background: The COVID-19 pandemic led to mass vaccination across the globe and resulted in several unintended consequences, one of which being reactive lymphadenopathy mimicking malignancy. A large study reported hypermetabolic lymphadenopathy (HLN) in over 45% of patients after receiving at least one dose of COVID-19 vaccine. A study on breast cancer patients noted a near-400% increase in lymphadenopathy on MRI and ultrasonography over the two years prior to mass vaccination. These findings present a dilemma in patients with treated malignancy while under surveillance. As vaccination became more commonplace, a case series reported on patients with PET-detected lymphadenopathy, with biopsies confirming VRLN. These investigations contributed to general recommendations on the importance of clinical context in patient care after COVID-19 vaccination. We present a unique study that evaluates patients with treated solid and hematological malignancies that presented with HLN after COVID-19 vaccination which emphasizes the importance of clinical acumen in the management of oncological patients in the pandemic era. Methods: We identified 6 patients aged 39-95 with prior malignancy. 5 were diagnosed with metastatic melanoma, and one had a diagnosis of high-grade B-cell lymphoma. Patients were managed with chemotherapy, immunotherapy, surgery, radiotherapy, or a combination of modalities, and were in complete radiological remission. All patients received at least two doses of a COVID-19 vaccine, with one dose at least three weeks prior to a routine surveillance PET-CT. Each patient exhibited HLN. Results: Of six patients, three underwent biopsy. There was no evidence of malignancy in any biopsy, and VRLN was confirmed. The remaining patients were followed with surveillance, and all had resolution of HLN without intervention. Time between COVID-19 vaccination and PET evidence of HLN ranged from 19 to 232 days. Time between first positive and first resolved PET ranged from 92 to 463 days. All patients were alive at the time of abstract submission. Conclusions: Our study emphasizes the importance of a focused history when suspecting recurrent malignancy, especially after sustained remission in our vulnerable populations. Acknowledging that COVID-19 vaccination can lead to HLN is becoming more common, and we show that this can occur, persist, and resolve even months after vaccination. While high suspicion for recurrence should be maintained, all efforts should be taken to protect patients and prevent unnecessary procedures. Records of recent vaccinations should be available and reviewed prior to radiological studies and clinical decisions, which can reduce avoidable interventions and harm. Surveillance of our patients proved to be an appropriate approach, and our study shows that similar patient presentations can have different paths of care depending on the awareness of treating physicians.