A 28-year-old male presents to his primary care physician with complaints of intermittent abdominal pain and alternating bouts of constipation and diarrhea. His medical chart is not significant for any past medical problems or prior surgeries. He is not prescribed any current medications. Which of the following questions would be the most useful next question in eliciting further history from this patient?

"Can you tell me more about the symptoms you have been experiencing?"

"Does the diarrhea typically precede the constipation, or vice-versa?"

"Is the diarrhea foul-smelling?"

"Please rate your abdominal pain on a scale of 1-10, with 10 being the worst pain of your life"

"Are the symptoms worse in the morning or at night?"

A 4-year-old boy is brought to a pediatrician by his parents with a history of fever for the last 5 days and irritability, decreased appetite, vomiting, and swelling of the hands and feet for the last 3 days. The patient’s mother mentions that he has been taking antibiotics and antipyretics prescribed by another physician for the last 3 days, but there has been no improvement His temperature is 39.4°C (103.0°F), pulse is 128/min, respiratory rate is 24/min, and blood pressure is 96/64 mm Hg. On physical examination, there is significant edema of the hands and feet bilaterally. There is a 2.5 cm diameter freely moveable, nontender cervical lymph node is palpable on the right side. A strawberry tongue and perianal erythema are noted. Conjunctival injection is present bilaterally. Laboratory findings reveal mild anemia and a leukocytosis with a left-shift. Erythrocyte sedimentation rate (ESR) and serum C-reactive protein (CRP) are increased. If not treated appropriately, this patient is at increased risk of developing which of the following complications?

Lower gastrointestinal hemorrhage

Acute disseminated encephalomyelitis (ADEM)

A 5-year-old girl presents with a rash and a persistent fever of 41.0°C (105.8°F), not relieved by Tylenol. The patient's mother says that her symptoms started 5 days ago and have not improved. The rash started on her trunk and now is present everywhere including the palms and soles. Her birth history is normal. Her pulse is 120/min and respiratory rate is 22/min. On physical examination, the patient is agitated and ill-appearing. There is significant swelling of the distal upper and lower extremities bilaterally. The pharynx is hyperemic (see image). Generalized edema with palpable cervical lymphadenopathy is noted. Muscle tone is normal. Remainder of exam is unremarkable. Laboratory findings are significant for the following: Laboratory test Hb 9 g/dL RBC 3.3/mm3 Neutrophilic leukocytosis 28,000/mm3 Normal platelet count 200,000/mm3 Serum ɣ-GT increased Hyperbilirubinemia 2.98 mg/dL AST and ALT are normal, but there is markedly increased serum CRP. Which of the following is the most likely diagnosis in this patient?

Staphylococcal scalded skin syndrome

A previously healthy 4-year-old boy is brought to the physician by his parents because he has had a fever, diffuse joint pain, and a rash on his abdomen for the past week. Acetaminophen did not improve his symptoms. He emigrated from China with his family 2 years ago. He attends daycare. His immunization records are not available. His temperature is 38.5°C (101.3°F), pulse is 125/min, and blood pressure is 100/60 mm Hg. Examination shows polymorphous truncal rash. The eyes are pink with no exudate. The tongue is shiny and red, and the lips are cracked. The hands and feet are red and swollen. There is right-sided anterior cervical lymphadenopathy. Which of the following is the most appropriate next step in management?

HHV-6 immunoglobulin M (IgM) detection

Antistreptolysin O titer measurement

A previously healthy 3-year-old girl is brought to the physician by her parents for the evaluation of recurrent episodes of pain in her left wrist and right knee for 4 months. She has not had any trauma to the knee or any previous problems with her joints. She attends daycare. Her mother has rheumatoid arthritis. Her vital signs are within normal limits. Examination of the right knee and left wrist shows mild swelling, tenderness, warmth, and erythema; range of motion is slightly decreased. No other joints are affected. The remainder of the examination shows no abnormalities. Laboratory studies show: Hemoglobin 12.4 g/dL Leukocyte count 9,000/mm3 Platelet count 200,000/mm3 Erythrocyte sedimentation rate 50 mm/h Serum Antinuclear antibodies 1:320 Rheumatoid factor negative This patient is at increased risk for which of the following complications?

Inflammation of sacroiliac joints

Recurrence risk for USMLE Step 2 CK: High-Yield Pediatrics Lessons

Recurrence Rates - The KD Encore

Recurrence vs. Recrudescence
- Recurrence: A new, distinct episode of Kawasaki Disease (KD) after complete recovery.
- Recrudescence: Relapse of fever and symptoms within days of initial IVIG, indicating treatment resistance.
Incidence & Timeline
- Overall rate is low: ~1-3%.
- Most recurrences (>50%) happen within 2 years of the initial episode.
- Risk may be higher in patients who required a second dose of IVIG.

⭐ High-Yield Fact: Patients who develop coronary artery abnormalities (CAA) during their first KD episode are at a significantly higher risk for recurrence compared to those without CAA.

Risk Factors - Predicting a Relapse

Host-Related Factors:
- Male sex
- Age < 1 year at onset
- Genetic predisposition (e.g., ITPKC polymorphisms)
Treatment & Disease Course:
- Delayed IVIG therapy (> 10 days of fever)
- Resistance to initial IVIG treatment
- Severe initial inflammation (↑ CRP, ↑ ESR)
- Presence of coronary artery lesions (CALs) during the first episode

⭐ Patients resistant to initial IVIG therapy have a significantly higher risk of developing coronary artery aneurysms and subsequent recurrence.

Diagnosis & Features - Spotting the Sequel

High Index of Suspicion: Essential for any patient with a history of Kawasaki Disease (KD) presenting with unexplained fever.
AHA Criteria for Recurrence:
- Unexplained fever reappears and lasts ≥48 hours.
- Accompanied by ≥3 of the original principal clinical criteria.
- If fever is present with <3 criteria, evaluate for incomplete recurrent KD.
Role of Echocardiography:
- Absolutely critical at the time of suspected recurrence.
- Aims to detect new or worsening coronary artery abnormalities (CAA).

⭐ Recurrence risk is highest within the first 2 years of the initial illness and is more common in patients who had cardiac complications initially.

Management - The Retreatment Playbook

Standard First-Line: IVIG 2 g/kg as a single infusion + high-dose aspirin.
IVIG-Resistant KD: Persistent or recrudescent fever ≥36 hours after initial IVIG.

Aspirin Regimen:
- Anti-inflammatory: 80-100 mg/kg/day until afebrile for 48-72 hrs.
- Anti-platelet: Taper to 3-5 mg/kg/day for 6-8 weeks (or longer if coronary abnormalities).

⭐ Infliximab (5-10 mg/kg), a TNF-α inhibitor, is a key second-line agent, especially effective in refractory cases and for rapid control of inflammation.

High‑Yield Points - ⚡ Biggest Takeaways

Recurrence of Kawasaki Disease (KD) is uncommon (approx. 1-3%), with most cases occurring within 2 years of the initial episode.

Major risk factors for recurrence include male sex, age <1 year, and significant cardiac involvement during the first illness.

Recurrent episodes are often milder and carry a lower risk of developing new coronary artery aneurysms.

Management of a recurrent episode is identical to the primary one: high-dose IVIG and aspirin.

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Recurrence risk