Patient is an 80 year old male who has a history of multiple medical problems, including body mass index of 30, hypertension, dyslipidemia, giant-cell arteritis on a slow prednisone taper (currently 2 mg daily), past pulmonary embolism on warfarin, sleep apnea, history of diverticulitis (treated in August 2020), past abdominal surgeries (including umbilical hernia repair ×2 and open recurrent incarcerated epigastric hernia repair with mesh in October 2020), chronic anemia, and type-2 diabetes.  The patient had received the first dose of the COVID-19 (SARS-CoV-2) vaccine on January 31, 2021 and the second dose on February 21.  He presented to his primary care provider?s office on February 22, 2021 with complaints of 10 days of progressive weakness and muscle soreness.  The weakness had reportedly involved the bilateral thighs and arms and was associated with muscle aches.  Blood pressure measured 90/40 mmHg and examination was notable for symmetrical proximal weakness in the upper and lower extremities.  The peripheral blood leukocyte count measured 3.5 x10e3/µL, hemoglobin 8.3 grams per deciliter and platelets 147 x10e3/µL.  A peripheral blood smear was consistent with neutropenia and normocytic anemia with 9% circulating blasts.  Total CK measured 1424 U/L.  The patient was referred to hematology/oncology and rheumatology and had appointment scheduled for both on February 26.    With the above background, he presented to emergency room on February 24 with altered mental status and continued weakness.   He was taken to the hospital by emergency medical services.  A temperature of 103 degrees Fahrenheit was recorded when emergency medical personnel had arrived. The peripheral blood leukocyte count was 1.4 x10e3/µL for an ANC of 0.8 x10e3/µL.  Hemoglobin was 8.1 g/dL and platelets 111 x10e3/µL.  A few schistocytes and teardrop cells were noted. The serum creatinine was 1.47 mg/dL.  AST was 174, ALT 91 and alkaline phosphatase 93 U/L.  The lactic acid level of the venous blood was 2.1 mmol per liter.  A repeat total CK was 4631 U/L.  Sedimentation rate measured 34 mm/h and CRP 52.3 mg/L.  Urinalysis showed 0-2 wbc?s/hpf, 0-2 rbc?s/hpf, 3+ blood, negative nitrites, negative leukocyte esterase.  A haptoglobin level of the blood was within normal limits. The lactic acid level of the venous blood was 2.0 mmol/L.  LDH measured 838 U/L.  A ferritin level was 3464 nanograms/mL.  A test for COVID-19 (SARS-CoV-2) was negative.     A chest radiograph showed minimal streaky right basilar atelectasis, trace left effusion and a mildly enlarged cardiac silhouette.  A head CT showed no acute abnormality.  An abdominopelvic CT without contrast was limited by motion artifact.  No acute intra-abdominal or pelvic finding was noted.  Nonspecific soft tissue stranding was seen in the right inguinal region.  There was no soft tissue gas or drainable fluid collection.  Cultures of specimens of the blood were obtained.  The patient was started on empiric cefepime, vancomycin and doxycycline and admitted for further care. A peripheral blood smear for intracellular parasites was negative.  The admission blood cultures came back positive for E. coli. With the blood culture results, the vancomycin and doxycycline were discontinued.  The E. coli isolate has since been determined to be pansusceptible.  A MRSA PCR of the nares was negative.   He was found on exam to have swelling, cellulitis and exquisite pain of the right groin area on February 25.  Surgical consultation was pursued.  They did not feel that he had necrotizing fasciitis.  The CT scan of the abdomen and pelvis was repeated with contrast, revealing increased extensive subcutaneous edema of the right groin region with extension into the thigh musculature and mild extension into the right inferior pelvis.  There was no associated soft tissue gas or drainable abscess. A bone marrow biopsy was performed February 25.  Results showed acute undifferentiated leukemia with 60-70% infiltration of the bone marrow with blasts.  The blasts were negative for lineage markers.  He was faintly CD33 positive.  He is felt to likely have acute myeloid leukemia. Cytogenetics are pending.