Inflammatory response following neutrophil recovery postchemotherapy in acute myeloid leukemia cases without evidence of infection: role of homing of neutrophils
A 32-year-old woman with remote history of pilonidal abscess presented with easy bruising, fatigue, generalized bony pain, and heavy menses. She was found to have acute myeloid leukemia (AML) with 34% bone marrow blasts and t(8;21) (q22;q22). She was placed on levaquin, acyclovir, and posaconazole for prophylaxis, and induction chemotherapy with standard daunorubicin and cytarabine was initiated for a total of 7 days. While neutropenic, she developed an area of tenderness and erythema around her sacrum in the previous site of a pilonidal cyst and then became febrile. Cefepime was initiated, and was later changed to vancomycin and piperacillin/tazobactam because of suspected rash from cefepime. She remained febrile for 3 days after initiating antibiotic therapy. Blood cultures were drawn and remained negative. Computed tomography (CT) of the pelvis revealed ill-defined soft-tissue thickening in the mid-lower back from the lumbar spine to the sacrum within the deep subcutaneous fat to the gluteal crease without any evidence of muscular involvement. There was also a well-defined fluid collection measuring approximately 2.9 × 0.8 cm within the subcutaneous tissues, superficial to the lower sacrum and to the right of the midline (). Erythema and fever resolved, and tenderness improved with antibiotics. Vancomycin was discontinued after 48 hours, but piperacillin/tazobactam was continued until her neutrophil count became >500 neutrophils/μL. The total duration of antibiotic therapy was 11 days. A postinduction bone marrow evaluation revealed no residual leukemia.\nAfter 48 hours off antibiotics, the presacral tenderness and redness returned. Examination revealed an area of fluctuance, erythema, and tenderness in the same location of her previous pilonidal cystectomy. At this time, her absolute neutrophil count (ANC) was 2,500/μL. CT of the pelvis showed an increase in size of well-defined fluid collection, measuring 1.3 × 2.2 × 6.4 cm (). She was off antibiotics for 48–72 hours before aspiration, and drainage was performed. Foul, cloudy, purulent fluid was aspirated and sent for analysis. This showed many neutrophils with no organisms, and cultures were negative. The patient was placed on ertapenem, and her symptoms improved primarily after initial drainage. Follow-up sonogram, done after 3 days, showed a mild complex fluid collection within the subcutaneous tissues. She underwent incision and drainage of the area of greatest redness. Retrieved tissue and fluid were sent for cultures and remained negative again. Gram stain of the swabbed fluid showed rare neutrophils, and no organisms were seen. The area healed well, and after 12 days she proceeded with treatment for her AML with a matched-sibling donor stem cell transplant without complications.\nThe second case was a 52-year-old male patient who presented with pancytopenia, 35% myeloid blasts in the bone marrow, fever, chills, and tachycardia, with redness, swelling, and pain involving the medial posterior left thigh, and mild redness and swelling but no pain of the lateral aspect of the right thigh. Magnetic resonance imaging (MRI) of the left thigh showed pyomyositis with extensive edema throughout quadriceps musculature, with focal areas of myonecrosis and intercommunicating pockets of fluid. Creatine phosphokinase was 905 U/L. There was also subcutaneous edema suggestive of cellulitis. He was diagnosed with AML and sepsis. Peripheral blood, bone marrow, and urine cultures obtained initially showed no bacterial or fungal infection. He was started on vancomycin, cefepime, and clindamycin, and then changed to vancomycin and piperacillin/tazobactam after 8 days. AML induction therapy with daunorubicin and cytarabine was initiated for a total of 7 days. Surgical intervention was considered but not done, due to clinical improvement while on antibiotics.\nWith antibiotic therapy, the patient became afebrile with decreased pain, swelling, and redness of the left upper thigh and stabilization of the right thigh. On postinduction day 21, the ANC was 80/μL, and while on piperacillin/tazobactam, the patient developed fever. A repeat MRI showed progressively evolving areas of myonecrosis/abscess in the left thigh, predominately in the abductor brevis and magnus, and unchanged to slightly decreased area of myonecrosis/abscess in the proximal right thigh, with slightly increased enhancement and edema in the adductor magnus (). Orthopedic surgery was reconsidered, and it was thought that overall the abscesses were unchanged. Blood cultures were drawn and were negative. Slowly, his symptoms improved with antibiotics, and he was discharged off antibiotics after he became afebrile and had recovered his neutrophil count (ANC was 666/μL upon discontinuation of antibiotics).\nThree days later, he presented with severe pain and increased swelling in his left thigh. His white blood cell count was 8,800/μL at that point. On examination, his left thigh was swollen and painful to the touch without any fuctuation. A repeat MRI showed marked progression and enlargement of multiple fluid collections in the left thigh consistent with worsening areas of myonecrosis/abscess (). Routine blood cultures and one fungal blood culture were obtained, and showed no growth. Prior to reinitiation of antibiotic therapy, a CT-guided aspiration was done and a drain placed. The recovered fluid showed no bacteria, fungus, or mycobacteria. Gram stain, however, showed many neutrophils and red blood cells, but no organisms. Following the procedure, his left thigh pain improved; however, his pain dramatically improved with anti-inflammatory agents. Vancomycin and piperacillin/tazobactam were started, and later changed to ertapenem. The drain output slowed down and became insignificant 15 days post-drain placement. Ertapenem was stopped 20 days after drain placement. The patient remained afebrile and proceeded with subsequent chemotherapy.