22-year-old woman presents with a single hyperpigmented lesion on back.
Has this brown spot changed in size or color?
It has grown a bit with me but not otherwise changed.
The growth pattern of a pigmented lesion is always important, especially if malignant change is suspected. Many such lesions growth as the patient grows.
How long have you had it?
Since I was born.
Good question, as it helps to narrow down the differential diagnostic considerations.
Do you have any other similar lesions?
Yes, I have one more.
Good question. If a patient has 5 or more such lesions, one must consider a common genodermatosis.
What kind of work do you do?
I work in a chemical laboratory.
Even though such a lesion is not work-related, an occupational history helps you exclude mental retardation which is seen in some syndromes with such lesions.
Does the spot itch?
No, it just bothers me a little because of its appearance.
Good question, as it helps to exclude a fungal infection, which usually itches.
Have you noticed smaller brown spots in your armpits?
A very specialized question; axillary freckling is another sign for neurofibromatosis, the genodermatosis most often associated with these lesions.
Choose the right efflorescences:
Good, this is a macule, as one can see it, but not locate it with touch alone.
A papule is raised, which is not the case here.
Lichenification means thickening of the skin, which is not the case here.
An erosion is a superficial skin defect. Here the skin is intact.
Choose the right diagnosis:
Lentigos are usually smaller and multiple, but otherwise similar
Very good. This is a classic café-au-lait macule. Solitary or few lesions of no significance; if a patient has more than 5 such lesions, then neurofibromatosis should be excluded.
Vitiligo is caused by depigmentation of the skin, usually presenting with white macules and patches. In extensive vitiligo, a patch of normal skin could be mistaken for a café-au-lait macule.
This doesn't fit. Dermatophyte infections are usually more red than brown, itch and have peripheral scale, where one can usually find the organisms on KOH examination.
Choose the right therapy(ies):
The risk of hypopigmentation is considerable.
The scar is usually worse than the lesion, especially on the back.
No therapy is needed in this case. Café-au-lait macules have no malignant potential.
Once again, the risk of depigmentation is considerable.
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