skip to main content
usmle step 2 ck

Tumor Lysis Syndrome & Oncologic Emergencies

Acute cancer-related emergencies including tumor lysis syndrome, hypercalcemia of malignancy, spinal cord compression, superior vena cava syndrome, febrile neutropenia, and leukostasis

Review date
reviewed 2026-05-04
Reading time
10 min read
Author
Dr Kola Tytler MBBS CertHE MBA MSt MRCGP
Hematology & Oncologyless-commonemergency
On this page
Condition details
Hematology & Oncology
less-common
10 min read
reviewed 2026-05-04
practice step 2 ck questions →

About This Page

This is a clinician-written, evidence-based summary aligned to the USMLE Step 2 CK Content Outline. It is intended for medical students preparing for USMLE Step 2 CK. Management reflects current ACC/AHA, USPSTF, and APA guidelines. Always cross-reference with UpToDate, institutional protocols, and clinical judgment.

Key points

  • Tumor lysis syndrome causes hyperkalemia, hyperphosphatemia, hypocalcemia, hyperuricemia, and acute kidney injury
  • Highest TLS risk occurs in bulky, rapidly proliferative, chemo-sensitive cancers such as ALL, AML, and Burkitt lymphoma
  • Prevention: aggressive IV hydration, allopurinol for intermediate risk, rasburicase for high risk or established hyperuricemia; avoid rasburicase in G6PD deficiency
  • Febrile neutropenia requires immediate antipseudomonal antibiotics after cultures are obtained when feasible
  • Spinal cord compression: steroids plus urgent MRI and radiation/neurosurgical evaluation

Overview

Oncologic emergencies are acute complications of cancer or cancer therapy requiring rapid recognition and treatment. They are high-yield because the next best step is often immediate supportive action before complete staging or definitive cancer treatment. Tumor lysis syndrome is the prototypical metabolic emergency, but Step 2 CK also tests hypercalcemia of malignancy, febrile neutropenia, spinal cord compression, superior vena cava syndrome, leukostasis, and malignant pericardial effusion.

Epidemiology

Risk depends on tumor type, burden, proliferation rate, treatment sensitivity, baseline renal function, dehydration, and pretreatment uric acid/LDH. TLS is commonest with hematologic malignancies but can occur in solid tumors. Spinal cord compression is most associated with breast, lung, prostate, myeloma, and lymphoma.

Clinical Features

Symptoms
TLS: nausea, vomiting, weakness, cramps, tetany, seizures, arrhythmia, oliguria
Febrile neutropenia: fever may be the only sign of life-threatening infection
Spinal cord compression: back pain, weakness, sensory level, urinary retention
SVC syndrome: facial swelling, dyspnea, cough, headache, venous distension
Hypercalcemia: constipation, polyuria, dehydration, confusion
Leukostasis: dyspnea, hypoxemia, headache, confusion, visual changes
Signs
Arrhythmia or ECG changes from hyperkalemia or hypocalcemia
Hypotension or sepsis signs in febrile neutropenia
Focal neurologic deficits, hyperreflexia, saddle anesthesia in cord compression
Facial plethora, upper extremity edema, dilated chest wall veins in SVC syndrome
Dehydration and altered mental status in hypercalcemia

Investigations

First-line
TLS labsPotassium, phosphate, calcium, uric acid, creatinine, LDH; repeat frequently in high-risk treatment windows
CBC with differential and ANCANC <500/µL or expected decline plus fever defines febrile neutropenia risk
ECGAssess hyperkalemia, hypocalcemia, and arrhythmias in metabolic emergencies
Second-line
Blood cultures and infection evaluationObtain before antibiotics if this does not delay therapy in febrile neutropenia
MRI spine with contrastBest test for suspected malignant spinal cord compression
CT chest with contrastEvaluate SVC syndrome cause and anatomy when patient is stable
Specialist
Cancer-specific staging and tissue diagnosisImportant but should not delay emergency stabilization when airway, cord, sepsis, or metabolic crisis is present
Nephrology consultationFor severe TLS, refractory hyperkalemia, severe AKI, or dialysis indications

Management

NCCN Supportive Care Guidelines; ASCO supportive oncology guidance
1
Tumor lysis syndrome
  • Aggressive IV hydration and close urine output monitoring
  • Allopurinol prevents new uric acid formation but does not rapidly lower existing uric acid
  • Rasburicase rapidly degrades uric acid and is used for high-risk or established TLS; contraindicated in G6PD deficiency
  • Treat hyperkalemia urgently; dialysis for refractory hyperkalemia, severe AKI, volume overload, or symptomatic hypocalcemia/hyperphosphatemia
2
Febrile neutropenia
  • Fever with ANC <500/µL or expected decline is an emergency
  • Obtain cultures if feasible, then give antipseudomonal beta-lactam promptly: cefepime, piperacillin-tazobactam, or meropenem
  • Add vancomycin only for specific indications such as catheter infection, skin/soft tissue infection, pneumonia, hemodynamic instability, or known resistant gram-positive infection
3
Spinal cord compression
  • Give corticosteroids promptly when malignant cord compression is suspected
  • Urgent MRI and radiation oncology/neurosurgery consultation
  • Definitive therapy may be radiation, surgery, systemic therapy, or combinations depending on tumor and stability
4
Other emergencies
  • Hypercalcemia of malignancy: IV fluids, calcitonin for rapid effect, bisphosphonate or denosumab for sustained control
  • SVC syndrome: elevate head, oxygen if needed, corticosteroids for steroid-sensitive tumors or airway edema, urgent oncology/radiation/stenting depending on severity
  • Leukostasis: urgent cytoreduction with hydroxyurea, leukapheresis in selected cases, and definitive leukemia therapy

Complications

  • Fatal arrhythmias: Hyperkalemia or hypocalcemia in TLS
  • Acute kidney injury: Uric acid and calcium-phosphate precipitation
  • Septic shock: Febrile neutropenia may progress rapidly with minimal localizing signs
  • Permanent paralysis: Delayed treatment of spinal cord compression
  • Airway or cerebral edema: Severe SVC syndrome
USMLE Step 2 CK Exam Tips
  • 1TLS labs: high potassium, high phosphate, low calcium, high uric acid
  • 2Allopurinol prevents uric acid formation; rasburicase removes existing uric acid
  • 3Rasburicase is contraindicated in G6PD deficiency
  • 4Febrile neutropenia: give cefepime/piperacillin-tazobactam/meropenem promptly
  • 5Back pain + cancer + neurologic symptoms = steroids and urgent MRI for cord compression
  • 6Hypercalcemia of malignancy: IV fluids first, calcitonin works fast, bisphosphonate works slower
  • 7Leukostasis causes respiratory and neurologic symptoms with very high WBC, especially AML

Put your reading into practice

Topic-specific question practice is not linked for this article yet.

Choose USMLE Step 2 CK questions from the existing bank. General exam practice covers your selected topics; it is not filtered to this article. Your usual question-bank access applies.

Choose USMLE Step 2 CK practice

After your session, return to this section to revisit the reading and choose your next review.

Verified Sources & References

NCCN Supportive Care Guidelines
ASCO Guidelines
ASH Clinical Practice Guidelines
Your learning path

Save your place and choose what comes next

sign in to save your learning

Hematology & Oncology · Article 24 of 24