Contributed by Jennifer Picarsic, MD and Lydia Contis, MD
CLINICAL HISTORY AND PHYSICAL EXAM
A 25-year old obese male presented to the emergency room via ambulance after a sudden change in mental status. He was previously well with multiple "sick-contacts" over the previous week and a history of hypertension. While in the emergency room, he developed worsening respiratory status with an increased oxygen demand.
He was initially afebrile with temperature of 36.8oC, blood pressure 120/60, respiratory rate of 18 breaths/minute, and a pulse oximeter reading of 89% on room air; 94% on 4L nasal cannula. Physical exam was significant for bilateral rhonchi.
On chest X-ray, there were large areas of consolidation in the right mid zone, right base, and in the left mid zone of the lung compatible with bilateral pneumonia. An EKG was significant for sinus tachycardia. While in the emergency room, his temperature rose to 41oC (rectally), and he became tachypneic with respiratory rate of 40. He was transferred to the intensive care unit and given maximal support including triple antibiotic coverage and triple pressors to maintain blood pressure, which had fallen to 80/30-40s.
White blood cell count (normal range): 1.7 x 109/L (3.8-10.6).
Hemoglobin (normal range): 15.3 g/dL (12.9-16.9)
Hematocrit (normal range): 44.4% (38-48.8%)
Platelets (normal range): 129 x 109/L (156-369)
Neutrophils: 28%, Bands: 9%, Lymphocytes: 48%, Monocytes 13%, Atypical lymphocytes: 2%.
Glucose: 137 mg/dL (70-99); creatinine 2.1 mg/dL (0.5-1.4); BUN 20 mg/dL (9-20).
Blood gas: pH 7.3 (7.35-7.45), pCO2 31 mmHg (35-45), pO2 53 mmHg (60-100), bicarbonate 15 mEq/L (22-26).
Sputum culture-Heavy Staphylococcus aureus. The isolate is Methicillin Resistant Staphylococcus aureus (MRSA).
What other tests would you order?
ADDITIONAL CLINICAL COURSE
The patient acutely decompensated with worsening respiratory status requiring intubation and positive end-expiratory pressure (PEEP). Soon after, he also developed renal failure with elevated creatinine of 2.9. The patient developed a blood clot around his dialysis catheter.
RNA PCR testing for Influenza was pending; however, the patient was started on oseltamivir and amantadine soon after admission for high clinical suspicion of influenza. A urinary Legionella antigen was negative. His laboratory values worsened with decreasing white blood cell count to 0.8 x109/L, thrombocytopenia 20 x109/L, and anemia, hemoglobin 11 g/dL; lactate was elevated at 13 mMol/L (0.7-1.8) and an arterial blood gas was significant for a mixed acidosis. He was started on filgrastim on his second admission day for his persistent leukopenia. Because of his pancytopenia, a bone marrow biopsy was performed with the following findings:
BONE MARROW HISTOLOGY
Figure 1. Hemodilute bone marrow aspirate. Wright-Giemsa 10x.
Figure 2. Bone marrow aspirate with hemophagocytic histiocyte. Wright-Giemsa 100x.
Figure 3. Hypocellular bone marrow biopsy. H&E 4x.
Figure 4. Bone marrow biopsy with hemophagocytic histiocytes within the sinus cavity (arrow). H&E 100x.
Figure 5. Bone marrow biopsy with hemophagocytic histiocyte within the sinus cavity (arrow). Note the paucity of mature myeloid cells. Inset: Hemophagocytic cell. PAS 100x.
Figure 6. Bone marrow biopsy. CD68 immunohistochemical stain highlights increased marrow histiocytes. 50x.
Figure 7. Bone marrow biopsy. Hemophagocytic histiocyte highlighted by CD68 immunohistochemical stain. (see arrow) 100x.
Figure 8. Bone marrow biopsy with abnormal megakaryocytes. Note megakaryocyte within the marrow sinus. PAS 50x.
Figure 9. Bone marrow biopsy. Increased reticulin fibrosis. Reticulin 40x.