This chapter introduces the classification of acute myeloid leukemia (AML) and highlights integrating both genetic and immunophenotypic findings in the diagnostic process. AML blasts exhibit a diverse immunophenotypic profile, and key markers associated with each immunophenotypic subtype are discussed. The assessment of measurable residual disease (MRD) is crucial in AML, as it provides important information regarding treatment response and prognosis. Both flow cytometry and molecular testing are used in MRD evaluation.

This chapter presents a case of a 47-year-old male with confusion secondary to hyponatremia, caused by beer potomania (excessive beer consumption). The case highlights the approach to a patient with an altered mental status, seizures, and severe hyponatremia. The approach to diagnostic testing, stabilization, and interventions to prevent progression and deterioration to a comatose state are described.

This chapter presents a case of an 89-year-old female with fever and altered mental status. The patient presents with systemic inflammatory response syndrome (SIRS) due to pneumonia. The case presents the medical interventions to mitigate progression to multiorgan dysfunction or septic shock.

This chapter provides the key immunophenotypic features of various subtypes of T-large granular lymphocytic leukemia (T-LGLL). The differential diagnosis of T-LGLL, including reactive T-LGL proliferation, T-cell clone of uncertain significance, and other T-cell leukemias/lymphomas, especially hepatosplenic T-cell lymphoma, is also discussed. Diagnostic pitfalls associated with T-LGLL are highlighted.

Generalized seizures that occur in children between 6 months and 5 years of age during a febrile illness and last less than 15 minutes are known as simple febrile seizures. Children may experience a brief post-ictal period but should return to baseline fairly quickly. Children with simple febrile seizures should be given antipyretics and a careful history and physical should be performed. If a source of the fever is identified, it should be treated. Most often, children do not require blood work or a lumbar puncture in the work-up of a simple febrile seizure. If the child has returned to baseline and is well-appearing, they may be discharged home with follow-up with their primary care physician. Complex febrile seizures, in contrast, may last longer than 15 minutes, may occur several times in a short period of time, or may be focal. A more thorough work-up is often required for complex febrile seizures.

This chapter focuses on several entities under splenic mature B-cell leukemia/lymphoma including hairy cell leukemia (HCL), hairy cell leukemia variant (HCLv), splenic diffuse red pulp lymphoma, and B-cell prolymphocytic leukemia. The key features are provided in recognizing each disease entity within the umbrella category of splenic B cell lymphoma/leukemia including splenic marginal zone lymphoma. For flow cytometry immunophenotyping, we illustrate the tips and pitfalls in gating, analysis, and interpretation. The chapter also extends the discussion to immunophenotypic variations of HCL/HCLv, phenotype-genotype discordance in HCL, and monoclonal B-cell lymphocytosis of uncertain significance (MBL) with a HCL or HCL-v phenotype.

This chapter covers the detailed immunophenotype of AML with DEK::NUP214 fusion. Different immunophenotypic subtypes (myeloid, myelomonocytic, and monocytic) are discussed. We focus on CD34-positive myeloblasts and describe the expression status and intensity of key markers.

The chapter describes a case of a 28-year-old female brought in by her boyfriend, who reports that the patient had a seizure. The patient is drowsy but arousable to painful stimuli and has vomitus on her clothes. The primary survey reveals dry and cool skin, normal capillary refill, and tachypnea. The patient is diagnosed with intentional tricyclic antidepressant (TCA) toxicity after admitting to taking a large number of pills. The critical actions include administering IV fluids, obtaining an EKG, alkalizing the serum, and managing TCA-induced seizures. The chapter provides pearls on the treatment of TCA toxicity, including the use of crystalloid fluids for hypotension and the greatest risk of seizures and arrhythmias occurring within the first 6−8 hours after ingestion.

This is a case of unstable bradycardia secondary to digoxin toxicity. Important early actions include administering IV fluids, IV atropine, treating for electrolyte abnormalities, obtaining serial EKGs and digoxin level, and treating with digoxin-specific antibody fragments. The candidate should not wait for digoxin level to treat with digoxin-specific FAB. Diagnosis should be made based off of clinical exam, history, and initial EKG. Digoxin toxicity can lead to life-threatening abnormalities in heart conduction. A classic visual complaint is xanthopsia, in which objects appear yellow/green. The candidate should initially cast a broad differential to exclude causes of altered mental status such as hypoglycemia, hypoxia, stroke, myocardial infarction, electrolyte abnormalities and infection. A thorough history should elicit her current medications, including digoxin, and a level should be ordered. As the case progresses the patient becomes increasingly unstable, bradycardic and hypotensive. The patient will not improve if digoxin-specific FAB is not administered despite attempting to correct hypovolemia and electrolyte disturbances and giving atropine and transcutaneous cardiac pacing. If the patient is transcutaneously paced, she will develop bidirectional ventricular tachycardia.

This chapter describes a case of a 7-month-old male who was brought to the emergency department after being found unresponsive and not breathing by his mother. The patient was cyanotic and limp, and CPR was initiated by EMS. The chapter outlines the PALS resuscitation protocol, including advanced airway, chest compressions, and addressing reversible causes of cardiac arrest. The patient was pronounced dead after significant and adequate resuscitation, and the family was provided with psychosocial support. The diagnosis was sudden unexpected death in infancy, and blood and urine were collected for postmortem testing. The chapter provides important information on the management of pediatric cardiac arrest and the importance of offering support to families in the event of sudden infant death.

This chapter covers initial diagnosis of B-lymphoblastic leukemia (B-ALL), and measurable disease detection (MRD) post therapy by flow cytometry. The classic and variant immunophenotypic features of B-ALL are illustrated, correlated with molecular genetic characteristics, and summarized in a genotype-phenotype table. The key features are provided in the differential diagnosis of B-ALL with aberrant MPO versus mixed B/myeloid acute leukemia (MPAL), as well as B-ALL with a mature phenotype versus high grade B cell lymphoma. Under B-ALL MRD detection, the common immunophenotypic alterations are demonstrated by comparing them to normal immature B cells (hematogones). Strategies for MRD detection post targeted therapy are also discussed. The pros and cons of flow cytometry MRD are compared with molecular MRD, including NGS sequencing (Clonoseq) and BCR::ABL1 quantitative PCR. The challenges, including loss of lineage markers, lineage switch, and normal mimics, are discussed and illustrated under diagnostic pitfalls.

This chapter covers the immunophenotypic features of acute myeloid leukemia (AML) with NPM1 mutation, the most common subtype of AML. In contrast, AML with NPM1 translocation is very rare but is also discussed. Preleukemic cells and clonal hematopoiesis are relatively common in AML with NPM1 mutation, and their distinction from residual AML is critical and highlighted. Other differential diagnosis includes the distinction between cases with an APL (acute promyelocytic leukemia)-like immunophenotype and real APL cases. Occasionally, AML with NPM1 mutation presents with less than 20% blasts and needs to be distinguished from other myeloid neoplasms such as myelodysplastic syndrome (MDS) and chronic myelomonocytic leukemia.

Palpitations is a common chief complaint in the emergency department. This case reflects a patient with palpitations found to have supraventricular tachycardia. It is imperative to determine the hemodynamic stability of the patient. As this case progresses, the patient is stable and the underlying rhythm can be determined and treated with various methods. Vagal maneuvers can be attempted but often fail. Adenosine must be given rapidly. The underlying cause is usually not determined in the emergency department, but physicians must consider life-threatening causes.

ALK-negative anaplastic large cell lymphoma (ALCL) is a mature T-cell neoplasm characterized by large pleomorphic cells with uniformly strong CD30 expression but without ALK rearrangement or expression. This chapter focuses on the immunophenotypic features of ALK-negative ALCL, including cases without and with DUSP22 rearrangement. The differential diagnosis of ALK-negative ALCL is also discussed, with a focus on flow cytometric immunophenotypic findings, including peripheral T-cell lymphoma, adult T-cell lymphoma/leukemia, NK/T-cell lymphoma/leukemia, T-lymphoblastic leukemia/lymphoma, and acute myeloid leukemia/myeloid sarcoma. Flow cytometric immunophenotypic features that can be helpful for the differential diagnosis are discussed.

This chapter describes the immunophenotype of acute myeloid leukemia (AML) with MECOM rearrangement in detail. Although MECOM rearrangement is predominantly identified in AML, it occasionally occurs in mixed-phenotype acute leukemia (MPAL). Both the immunophenotypes of AML and MPAL associated with MECOM rearrangement are discussed.