53-year-old Turkish mechanic came to the emergency room with a painful nodule on his back
Is this painful?
Yes, it really hurts.
A acute lesion is often quite painful.
How long have you had it?
For 2 days.
The time course can give clues to the etiology.
When were you out of the country the last time?
Last year I went to Turkey in the summer.
Travel history could give clues to an infection not usually seen in this area.
Have you ever had anything like this before?
A chronic course can give clues to the etiology.
Did you have an injury or bite at this spot just before?
Possible entry sites could point to an infectious cause.
Are you pregnant?
The second most important question after Are you taking any medications? but only for 50% of patients.
Choose the right efflorescences:
Technically, a tumor is a mass or swelling, so the answer is correct. Tumor does not equal cancer, although patients sometimes make this association.
It is an inflamed nodule.
A bulla is a fluid-filled space.
Hives are rarely solitary and usually itch, but are not painful.
A pustule is small blister filled with pus.
Choose the right diagnosis:
A furuncle is a deep infection of a hair follicle. The maximal variant with multiple coalescing furuncles is a carbuncle.
Lipoma is a benign fatty tumor.
Leishmaniasis can also present with a painful ulcerated nodule usually on the face. The patient's visit to Turkey was too long ago to make this a serious consideration.
Cutaneous B-cell lymphomas can present as a solitary nodule, but have a less acute course and are not intensely painful.
Erythema nodosum is a hyperergic reaction to various triggers (medications, infections) . It presents as bruise-like nodules, sometimes tender, almost always on the legs.
Choose the right therapy(ies):
Ubi pus, ibi evacua! Simple incision with cryoanesthesia is the easiest approach. The drain keeps the wound open so it can be disinfected again in 1-2 days.
This is a reasonable antibiotic treatment for uncomplicated cutaneous infections.
Incision and drainage is preferred; otherwise the lesion just fills up again.
Intravenous antibiotics are not needed here. Exceptions might be a central facial furuncle, systemic findings or an immunosuppressed patient.
This is insufficient use of disinfectants and corticosteroids are contraindicated.