Differential diagnosis of diphtheria

	Onset	Sore throat	Fever	Tonsillar enlargement	Tonsillar exudate	Cervical lymphadenopathy	Extraoral manifestations	Diagnosis
Diphtheria	Gradual	+	+	+/–	Gray, adherent and bleeds when scraped	+	Cardiac, neurologic involvement	Culture, PCR
Group A Streptococcus	Rapid	+++	+++	+ (edema of uvula)	Patchy, grayish to yellow	++	Headache, gastrointestinal symptoms	Culture, rapid test
Infectious mononucleosis	Gradual	++	++	++	Primarily pharyngeal with palatal petechiae	++	Generalized lymphadenopathy, splenomegaly	Heterophile Ab, serum Ab panel
Vincent's angina (acute necrotizing ulcerative gingivitis)	Rapid	+	+	–	–	–	–	Exam, imaging
Oropharyngeal candidiasis	Gradual	–	–	–	White with buccal and palatal involvement	–	+/– (depends on predisposing condition)	Wet mount, exam findings
Deep tissue infection of neck	Rapid	–	++	+/– (tonsil may bulge if abscess is present)	May be absent	–	Toxic appearance, often very painful, asymmetrical swelling common	Neck imaging
Lemierre's syndrome (septic thrombophlebitis of the internal jugular vein)	Gradual (pharyngitis prodrome followed by sepsis)	+	+++	+	Possibly exudative, ulcerative, or normal	–	Thrombosis of internal jugular vein, bacteremia, often toxic	Blood culture, CT imaging of jugular vein

PCR: polymerase chain reaction; Ab: antibody; CT: computed tomography.

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