WBR0376

Author	[[PageAuthor::Serge Korjian M.D. (Reviewed by Serge Korjian)]]
Exam Type	ExamType::USMLE Step 1
Main Category	MainCategory::Pathology
Sub Category	SubCategory::Renal
Prompt	[[Prompt::A 23-year-old Caucasian woman patient presents to the emergency department for confusion and altered level of consciousness. Appropriate history could not be taken due to the patient’s condition. Her temperature is 39.5 ᵒC (103.1 ᵒF), heart rate is 102/min and blood pressure is 90/50 mmHg. Physical examination reveals a petechial rash on predominantly on the lower extremities and significant nuchal rigidity. Blood cultures are withdrawn and broad spectrum antibiotic therapy is immediately initiated. The patient’s condition gradually improves over the next few days, but she remains anuric despite appropriate hydration. Blood cultures reveal 2 organisms: Neisseria meningitidis and Staphylococcus epidermidis. What is the most likely finding on CT scan in this patient?]]
Answer A	AnswerA::Bilateral renal infarcts
Answer A Explanation	AnswerAExp::Bilateral renal cortical necrosis is characterized by renal infarcts. In is a rare complication of DIC, pregnancy, and sepsis, trauma, and drugs.
Answer B	AnswerB::Adrenal hemorrhage
Answer B Explanation	[[AnswerBExp::Adrenal hemorrhage followed by adrenal gland failure is characteristic of Waterhouse-Friderichsen syndrome. Although the syndrome is also commonly due to N. meningitidis, symptoms of adrenal insufficiency would be prevalent, such as abdominal pain, hypotension, hyponatremia, and hyperkalemia. The patient’s general status improvement without additional intervention and urinary findings favor bilateral renal cortical necrosis in this case.]]
Answer C	AnswerC::Shrunken kidney size bilaterally
Answer C Explanation	AnswerCExp::Shrunken kidney size bilaterally is a characteristic finding of chronic kidney disease (CKD). Given the patient’s acute history, shrunken kidneys are unlikely to be present on CT scan.
Answer D	AnswerD::Tubular eosinophilic casts that look like thyroid tissue
Answer D Explanation	AnswerDExp::Thyroidization of the kidney is a finding on renal biopsy that is commonly found in several chronic renal diseases. The process is characterized by renal tissue that resembles that of thyroid on renal biopsy under light microscopy.
Answer E	AnswerE::Dilation of renal pelvis and calyces
Answer E Explanation	AnswerEExp::Hydronephrosis is characterized by the dilation of renal pelvis and calyces. The patient’s presentation is not compatible with hydronephrosis.
Right Answer	RightAnswer::A
Explanation	[[Explanation::Bilateral renal cortical necrosis is a rare phenomenon caused by significantly diminished renal arterial perfusion secondary to vascular injury, spasm, or coagulopathy. Sepsis, disseminated intravascular coagulation (DIC), and pregnancy-related complications are typical inciting events for renal cortical necrosis. Other causes include drugs and blunt trauma. Contrast-enhanced computed tomography (CT) is the imaging of choice to diagnose renal cortical necrosis. CT scan reveals acutely hypo-dense areas in the renal cortex bilaterally with enhancement of subcapsular and juxtamedullary areas. Care should be taken with these patients as further injury from contrast media administration is possible. Chronic kidney disease develops up to 50% of patients requiring long term dialysis and transplantation. Partial recovery of renal function is a possibility in certain patients. The mortality rate from renal cortical necrosis exceeds 50% in untreated patients. Educational Objective: Bilateral renal cortical necrosis is a rare complication of pregnancy-related medical conditions and sepsis. Contrast-enhanced CT scan is the imaging reveals bilateral renal infarcts that confirms the diagnosis. References: Chervu I, Koss M, Campese VM. Bilateral renal cortical necrosis in two patients with Neisseria meningitidis sepsis. Am J Nephrol. 1991;11(5):411-5]]
Approved	Approved::Yes
Keyword	WBRKeyword::Renal, WBRKeyword::Renal cortical necrosis, WBRKeyword::Kidney, WBRKeyword::DIC, WBRKeyword::AKI, WBRKeyword::Acute kindye injury, WBRKeyword::Sepsis
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