What is the most likely diagnosis for a patient with a sore throat, fever, severely swollen and edematous neck region, enlarged cervical lymph nodes, erythematous pharynx with bleeding spots, and inspiratory stridor, who has not received childhood immunizations?

Diphtheria

The most likely diagnosis is B. Diphtheria, given the combination of severely swollen and edematous neck ("bull neck"), inspiratory stridor indicating airway compromise, pharyngeal bleeding spots, and critically—the complete absence of childhood immunizations.

Clinical Reasoning Algorithm

Key Diagnostic Features Present

The clinical presentation demonstrates the classic triad of severe diphtheria:

• "Bull neck" appearance: The severely swollen and edematous neck region with enlarged cervical lymph nodes is pathognomonic for diphtheria, representing massive cervical lymphadenopathy and soft tissue edema from toxin-mediated vascular damage 1

• Airway compromise: Inspiratory stridor indicates upper airway obstruction, consistent with pseudomembrane formation causing mechanical obstruction—a life-threatening complication requiring urgent intervention 1

• Pharyngeal findings with bleeding: The erythematous pharynx with bleeding spots when swabbed strongly suggests pseudomembrane adherence to underlying tissue. The hallmark of respiratory diphtheria is a pseudomembrane in the pharynx that bleeds when attempts are made to remove it 1

• Unimmunized status: The absence of childhood immunization is the critical epidemiological factor. Diphtheria is vaccine-preventable, and cases occur almost exclusively in unimmunized or inadequately immunized individuals 1

Why Not Streptococcal Pharyngitis (Option A)

While streptococcal pharyngitis can present with fever, sore throat, and pharyngeal erythema, several features argue strongly against this diagnosis:

• Absence of "bull neck": Group A Streptococcus causes tender anterior cervical lymphadenopathy, but does NOT cause the massive neck swelling and edema characteristic of diphtheria 1, 2

• No inspiratory stridor: Streptococcal pharyngitis does not cause airway obstruction or stridor. This finding indicates pseudomembrane formation obstructing the airway—a feature of diphtheria, not strep throat 1

• Bleeding with swabbing: While strep throat causes tonsillopharyngeal exudates, these do not bleed when swabbed. The adherent, bleeding pseudomembrane is specific to diphtheria 1

• Clinical severity: The degree of neck swelling and systemic toxicity far exceeds typical streptococcal pharyngitis 1

Why Not Pertussis (Option C)

Pertussis presents with paroxysmal cough, post-tussive vomiting, and inspiratory whoop—not pharyngitis, neck swelling, or stridor. The clinical picture is entirely inconsistent with pertussis 1

Why Not Thrush (Option D)

Oral candidiasis (thrush) presents with white plaques that can be easily scraped off without bleeding, typically in immunocompromised patients or infants. It does not cause fever, neck swelling, or stridor. The clinical presentation is incompatible with thrush.

Critical Management Implications

This patient requires immediate life-threatening disease management:

• Urgent diphtheria antitoxin (DAT): Treatment must be initiated immediately without waiting for laboratory confirmation, as the degree of protection is inversely proportional to illness duration before administration 1

• Airway management: The presence of inspiratory stridor indicates impending complete airway obstruction. Intubation or tracheostomy may be necessary 1

• Antimicrobial therapy: Azithromycin or penicillin should be administered alongside antitoxin 1

• Isolation precautions: Respiratory diphtheria requires strict isolation to prevent human-to-human transmission 1

Common Pitfalls to Avoid

• Delaying antitoxin while awaiting culture results: DAT must be given on clinical suspicion alone. Waiting for microbiological confirmation can result in irreversible cardiac and neurological toxicity 1

• Mistaking for strep throat: The "bull neck" and stridor should immediately raise suspicion for diphtheria, not routine bacterial pharyngitis 3

• Underestimating airway compromise: Inspiratory stridor represents critical airway narrowing requiring immediate intervention 1

• Forgetting vaccination history: Diphtheria should always be considered in unimmunized patients with severe pharyngitis, even in industrialized countries where it is rare 4, 5