Thrombotic thrombocytopenic purpura (TTP) is a condition in which platelets aggregate abnormally in small blood vessels. Bleeding and multiorgan system complications can occur as a result. TTP is typically characterized by a classic pentad of symptoms: fever, hemolytic anemia, thrombocytopenia, renal impairment, and CNS impairment. Fever is the most common presenting symptom. A peripheral smear classically demonstrates schistocytes. Dialysis, anticonvulsants, or benzodiazepines may be indicated if the patient has significant renal impairment or seizure activity. The mainstay of treatment is plasma exchange with fresh frozen plasma. Initial treatment may also include steroids and antiplatelets. Platelet transfusions are avoided in TTP as additional platelets could exacerbate platelet aggregation, thrombosis, and, eventually, ischemia. Hematology consultation should be considered to help guide management.

Aggressive NK-cell leukemia (ANKL) is a systemic neoplasm of malignant NK cells driven by Epstein-Barr virus (EBV). It shares significant clinical and pathological overlap with extranodal NK/T-cell lymphoma. This chapter highlights the unique immunophenotypic characteristics of ANKL, providing insights into its distinction from related entities.

This chapter gives an overview of how flow cytometry (FCM) data are processed, visualized, and analyzed, along with general analysis strategies. Rather than delving into technical details (which are discussed in lab SOP and other publications), this chapter focuses on understanding the principles of FCM data analysis from a data analyst’s perspective and offers practical tips on how to assess data quality, recognize the technical constraints of the assay, and distinguish true signals from biological or technical artifacts. Moreover, in addition to traditional data analysis approaches, this chapter will also touch on the recent trend of using machine learning, or AI, for data visualization and analysis.

This chapter outlines the key immunophenotypic features of NK-large granular lymphocytic leukemia (NK-LGLL) and highlights the use of NK-cell receptor patterns, analyzed through flow cytometry, to establish NK-cell clonality. It also emphasizes the essential differences between NK-LGLL and its mimics, such as reactive NK-cell proliferation, NK-cell clones of uncertain significance, and aggressive NK-cell leukemia.

This chapter describes the diverse immunophenotypic features of AML with NUP98 rearrangement. The fusion partners for NUP98 are diverse, and accordingly, the immunophenotype differs depending on the specific partner involved. Immunophenotypic shift is relatively common in AML with NUP98 rearrangement. Rare cases with a mixed immunophenotype are present.

A septic cavernous sinus thrombosis (CST) is a rare, but serious, infection of a dural venous sinus that can be life-threatening if left untreated. As illustrated in this case, it often presents with headache, fever, eye pain, and photophobia. Proptosis and ophthalmoplegia are also commonly seen. The etiology of CST is often an adjacent sinus infection, but it can also result from odontogenic sources, trauma, bacteremia, or ear infections. The treating emergency physician should also consider orbital cellulitis, meningitis, or a brain abscess with this presentation. As emergency physicians prepare for their oral board examination, they should consider early and aggressive antibiotic therapy, imaging, and a lumbar puncture to all be critical actions. If CT is nondiagnostic, MRI should be pursued for more definitive diagnostic testing.

This is a review of the presentation and management of acute carbon monoxide toxicity.

This case reviews some typical features of the ED presentation of cholecystitis. Patients may present with abdominal pain, fever, an elevated white blood cell count, nausea, vomiting; the patient may have some or none of these symptoms. Maintaining a broad differential is important when a patient presents with these symptoms, but when specifically considering cholecystitis, there is utility in obtaining labwork and an RUQ ultrasound to aid in the diagnosis. The presence of gallstones, gallbladder wall thickening, pericholecystic fluid, and a positive sonographic Murphy’s sign are often seen in the diagnosis of cholecystitis. Maintaining IV access, obtaining a RUQ ultrasound, considering appropriate empiric IV antibiotics, and a surgery consultation are key in the management of acute cholecystitis.

This is a practice case about migraine headaches for the emergency medicine oral board examination. The case-based practice format goes from the patient’s chief complaint, history, and physical to the actions that the candidate must ask about or verbally “perform” in order to properly evaluate and treat the patient in the sample case. The case chapter also contains instructions for the examiner, and clinical pearls to review for exam preparation. The patient in this case needs to be questioned about risk factors and symptoms of potentially life-threatening secondary headaches, and then treated with certain medications, including a triptan, to help resolve her migraine headache that presents without aura (also called a “common migraine”).

This chapter covers the detailed immunophenotype of AML with CBFB rearrangement. We focus on CD34-positive myeloblasts and describe the expression status and intensity of key markers. The immunophenotypic features associated with different fusion transcripts are also highlighted. Minimal residual disease evaluation is discussed briefly.

This chapter discusses a critical diagnosis, hyperkalemia, and how to figure out the cause of seemingly vague complaints. It emphasizes the importance of the history and the EKG interpretation to get to the diagnosis rapidly and initiate treatment. After making the diagnosis, this chapter reviews the pharmacologic treatment of hyperkalemia, which all emergency physicians should know to prevent arrhythmias and even death. It also provides a nice review of the causes of hyperkalemia.

Isoniazid (INH) is a first-line medication for prophylaxis and treatment of active tuberculosis. In adults, INH toxicity can be due to INH overdose or noncompliance with the co-prescribed pyridoxine. In children, INH toxicity is usually due to accidental ingestion. Patients with INH toxicity typically present with nausea, vomiting, and mental status change. In the case of severe toxicity, patients will develop seizure, metabolic acidosis, coma, and even death. Seizures from INH toxicity are tonic-clonic in nature and refractory to standard seizure management, including benzodiazepines, barbiturates, and phenytoin. INH toxicity occurs because INH inhibits the production of the inhibitory neurotransmitter GABA via vitamin B6depletion. INH toxicity antidote is pyridoxine (vitamin B6). Treatment is 70 mg/kg IV empirically in children and adults. (Starting dose in adults is 5 g IV as this is based on a 70 kg adult.) If the amount of INH ingested is known, then the dose of pyridoxine is a gram-for-gram equivalent to the amount of INH ingested. Consider INH toxicity as cause of seizures in cases of refractory seizures. Always consider and ask about ingestions in children presenting with altered mental status, seizure, vomiting, or any ill-appearing child without a clear etiology.

This chapter delves into the cognitive processes involved in emergency medicine, emphasizing the reliance on pattern-matching, heuristics, and subconscious decision-making rather than conscious contemplation. It explores the use of mental shortcuts such as heuristics, including the “sick–not sick paradigm,” “age heuristic,” and the “ABCs heuristic” in making rapid and effective decisions. Analytic thinking is discussed as a more deliberate approach when other strategies are not yielding answers, while “shotgunning” is described as a last-resort cognitive strategy. The importance of a cognitive checkpoint to prevent errors and the need for conscious reflection in decision-making processes are highlighted. Overall, the chapter underscores the unique decision-making challenges and strategies in emergency medicine, aiming to optimize performance and enhance patient care.

This case study presents a 38-year-old female with a chief complaint of weight gain and fatigue over several months. Through a comprehensive assessment, it is revealed that the patient exhibits characteristic signs of Cushing syndrome, including amenorrhea, easy bruising, and purple striae. Initial laboratory results indicate elevated cortisol levels, supporting the diagnosis. The case underscores the importance of recognizing nonspecific complaints that may point to underlying endocrine disorders. Key actions involve endocrine consultation and follow-up. This study emphasizes the significance of early identification and management in preventing potential complications associated with untreated Cushing syndrome.

This chapter describes a case of a 2-month-old male preterm infant who presented with emesis and blood in the diaper. The patient has a weak cry, labored breathing, and periodic apnea. The physical exam reveals abdominal distension, tenderness, and bloody stools, which are concerning for sepsis. The patient is diagnosed with necrotizing enterocolitis, a serious condition characterized by intestinal inflammation that may lead to intestinal perforation, bowel necrosis, and/or death. The initial work-up includes sepsis evaluation, blood, urine, CSF cultures, CBC, electrolytes, and blood gas. X-ray findings include diffuse pneumatosis intestinalis, and portal venous air, which are pathognomonic for necrotizing enterocolitis. The mainstays of therapy include bowel rest, bowel decompression, and broad-spectrum antibiotics. Pediatric surgery is consulted, and the patient admitted for IV antibiotics and possible exploratory laparotomy.

A otherwise healthy patient presenting with a subacute acetaminophen overdose must be managed. This chapter highlights the appropriate management of acetaminophen overdose with N-acetylcysteine, based on time and quantity of ingestion.

This is an oral certification examination simulation case scenario of an adult patient with acute ethylene glycol intoxication and subdural hematoma manifesting with acute mental status change.