Differentials
Aphthous stomatitis or oral aphthous ulcers
SIGNS / SYMPTOMS
Ulcers are on the mucosal surfaces of the mouth.
The child is well, with no fever, malaise, or rash.
INVESTIGATIONS
Diagnosis is clinical.
Herpes simplex
SIGNS / SYMPTOMS
In most cases, there is a high fever, >38°C (>100.4°F).
Acute gingivitis and widespread oral ulceration are present.
On the skin, the vesicles are small and oval, on an erythematous base, and grouped together.
Usually no rash on the palms and soles, although young children who suck their fingers or toes may have lesions on 1 or 2 digits.[6]
INVESTIGATIONS
A Tzanck smear of vesicle fluid will show multi-nucleated giant cells.
A direct fluorescent antigen test for herpes simplex virus can also be done.
These tests are rarely indicated as the diagnosis can usually be made clinically.
Herpangina
SIGNS / SYMPTOMS
Cervical lymphadenopathy is present, and ulcers are also seen on the soft palate.
A rash does not usually occur.[6]
INVESTIGATIONS
Diagnosis is clinical.
Chickenpox
SIGNS / SYMPTOMS
The rash is usually limited to the trunk and extremities and highly pruritic. The classic lesion is a round vesicle on an erythematous base that evolves into a pustule.[6]
INVESTIGATIONS
A direct fluorescent antigen test for varicella virus.
Scarlet fever
SIGNS / SYMPTOMS
Pharyngitis, anterior cervical adenopathy, and fever precede characteristic scarlatiniform rash (diffuse, finely papular, 'sandpaper-like', erythematous rash that blanches with pressure). Rash begins on the trunk and may spread; it is accentuated in flexural creases (i.e., under the arm, in the groin, in the elbows) often with petechiae, producing red streaks known as Pastia's lines. Cheeks flushed 'scarlet' with circumoral pallor. Skin desquamation may occur 3-4 days after appearance of the scarlatiniform rash. Tongue may be inflamed with a white coating and prominent papillae ('strawberry tongue').
INVESTIGATIONS
Group A streptococcal rapid antigen test; polymerase chain reaction test, or throat/skin swab culture. Diagnosis is often clinical.
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