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Simple cases
Case 23
A worried mother brings her 8-year-old son because he has rapidly changing lesions on his face.
History
Does anyone else in the family or at school have similar lesions?
Yes, his little sister has a few spots, but much smaller.
Possible suggestion of an infectious etiology.
Do you have household pets?
Yes, an aquarium.
Furry animals, especially cats, can transfer dermatophytes.
Do the sores itch?
Yes, and each time he scratches, there are new spots.
Scratching may help explain how the lesions are spreading.
How did the lesions look at the start?
Just like now, just smaller.
The clinical evolution of lesions often points towards the etiology.
Have the lesions been treated?
Yes, we used a homeopathic ointment but it didn't help.
Knowledge about prior treatment may give clues to diagnosis and will help plan future therapy.
Did he ever have eczema?
No
Atopic dermatitis can predispose children to skin infections.
Does anyone in the family have psoriasis?
His paternal grandmother is supposed to have had something, but I have no idea.
The family history is relevant for psoriasis, but there is not good clinical evidence for the diagnosis here. When patients describe diseases in past generations, the margin of error is large.
Lesion
Choose the right efflorescences:
Pustules are pus-filled spaces. The disease usually starts with pustules but they are not seen today.
Crusts are scales mixed with pus, serum or blood.
No definite scales are seen.
Two of the lesions without crusts are eroded.
A fissure is a superficial linear defect.
Diagnosis
Choose the right diagnosis:
The primary lesion is a papule with serum. Dermatitis is usually not as circumscribed as these lesions.
Honey-colored crusted on an erythematous base are classic for impetigo. Watch for glomerulonephritis.
Herpes simplex presents with grouped vesicles. It may become secondarily infected (impetiginized) and then appear similar. History is essential.
Perioral dermatitis features papules and no crusts; almost unheard of in an 8-year-old boy.
Pityriasis rosea rarely involves the face and is much less inflamed.
Therapy
Choose the right therapy(ies):
Topical therapy can usually control localized disease.
Since impetigo is usually caused by Staphylococcus aureus, a penicillinase-resistant penicillin or a cephalosporin should be chosen.
Washing alone is not adequate.
An effective but very expensive topical therapy.
