51-year-old woman has noticed a lump on her shin which is getting darker
Does your partner have similar lesions?
No, why are you asking? Is this a sign of a venereal disease?
Terrible question. Even though syphilis can mimic almost all lesions, this is not one of them.
Were you in the tropics recently?
No, we were in Spain last summer, but that's it.
Good idea to ask about travel. But this common lesion has no connection to the tropics.
When did you first notice this bump?
I think I remember it from about 7 years ago. It has gotten darker recently and itches a bit.
The time course is important for all tumors. Rememberfor a patient, tumor = cancer, so use the world carefully.
Does anyone in your family have lesions like this?
No. My grandmother has lots of red, scaly spots in the face. Is that cancer?
There are melanoma-prone families and multiple epithelial tumors are sometimes markers for internal malignancies. Don't forget to answer the question about the grandmother; she probably has actinic keratoses.
Do you have any other similar lesions?
Yes, I have another one on the right calf, but it is less pigmented.
Good question. These lesions are usually solitary or few in number. Some patients may have a tendency to develop such lesions.
Have you spent a lot of time in the sun?
Sure, as a child. Now I am pretty careful ,since once reads so much about sun and skin cancer.
This lesion has nothing to do with sun exposure. The usual trigger is an arthropod bite or sting.
Choose the right efflorescences:
This lesion is raised and palpable, so it can't be a macule.
An erosion is a superficial defect, not seen here.
This is a classic papule.
A nodule is > 1cm, but the distinction is arbitrary.
Choose the right diagnosis:
A solitary lesion is unusual for sarcoidosis, as is the absence of granulomas on diascopy.
Solitary, chronic flea bites lasting 7 years do not exist. But an arthropod bite or sting might have started this reactive process.
This is a classic dermatofibroma, also known as histiocytoma. The lesion is typical a firm papule or nodule, adherent to the epidermis. In addition, when a dermatofibroma is pressed from the sides, it dimples (Fitzpatrick sign). Dermatofibromas may be quite dark, as they contain both iron and melanin.
The clinical course points away from melanoma. Dermatoscopy can also be helpful. If any question remains, do an excision!
Choose the right therapy(ies):
If the diagnosis is clear, then no treatment is the best treatment.
This treatment is of no value.
If necessary (pain, cosmetic problem) , excision is appropriate. Often the scar appears about as bad as the dermatofibroma.
It is almost imposable to curette such a firm dermal tumor, and the resulting scar would be unacceptable.
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