Soru

A retired $68$-year-old teacher presents to the emergency department reporting two days of profound fatigue and noticeably reduced urine volume. Four days ago, he underwent an urgent percutaneous coronary intervention with stent placement for a non-ST-segment elevation myocardial infarction. He was discharged the following day in stable condition. His medical history is notable for hypertension, type 2 diabetes mellitus, and hyperlipidemia. Current medications are aspirin, clopidogrel, atorvastatin, and metoprolol.

His temperature is $37.2^\circ\text{C}$ ($99.0^\circ\text{F}$), blood pressure is $158/92\text{ mmHg}$, and pulse is $84/\text{min}$. Physical examination reveals a lacy, purplish discoloration in a reticular pattern over his bilateral thighs and lower legs that does not blanch with pressure. The toes on his right foot appear cyanotic, although bilateral dorsalis pedis and posterior tibial pulses are strong and symmetric.

Laboratory studies show:
- Hemoglobin: $13.2\text{ g/dL}$
- Platelet count: $210,000/\mu\text{L}$
- Leukocyte count: $10,500/\mu\text{L}$ (Neutrophils $65\%$, Lymphocytes $25\%$, Eosinophils $10\%$)
- Blood urea nitrogen: $48\text{ mg/dL}$
- Serum creatinine: $2.9\text{ mg/dL}$ (baseline prior to the procedure was $1.1\text{ mg/dL}$)
- Urinalysis: $1-2\text{ RBCs/hpf}$, trace protein, and positive for urinary eosinophils.

Based on these clinical and laboratory findings, which of the following is the most likely diagnosis?