Question: 10 years ago I had a small bump removed from my back, near my spine. It was mostly painless but eventually became painful after years. It was marble sized or less. I believe if was diagnosed as a cyst, but this removal was done at an urgent care clinic, so I’m not sure if any pathology was done.

Recently, within the past few months, I’ve felt it grow back. During the past few weeks I’ve noticed that it grew back and has become painful when pressure applied to it. I went to the same urgent care clinic (too difficult to get a dermatologist appointment). The doctor said it was probably a cyst, cut into it, said it was “a little but pusy, “packed” it, applied a dressing, gave me a prescription for a 10 day course of Bactrim, said to return in a few days to have the packing removed, and advised to follow up with a dermatologist or a surgeon in case the “core” was not removed.

So, I have several questions.

1) Based on this description, does this indeed sound like a cyst? (I will try to attach a photo of the pre-removal lump). In other words, should I be concerned that it is something cancerous like a liposarcoma?

2) Is the fact that the original procedure, 10 years ago, was also performed at urgent care clinic a possible reason why the growth grew back? That is, the “core” was not removed?

3) Regarding Bactrim. I am not sure if i have a sulfa-drug allergy. I don’t believe I do, and I may indeed have taken a sulfa drug before without incident. I simply can’t remember. Is this drug truly necessary under the circumstances? I am traveling out of the country to propose to my girlfriend in less than a week—I am concerned that I will develop a rash by then and, obviously, this will not be ideal for the occasion (or for international travel).

Thanks in advance.

Dr. Ansmeet,

Thanks for your response. I will ask about switching to one of the other antibiotics you mentioned. Do you understand them to be generally better tolerated without complication? I think zithromycin may have been the only antibiotic I’ve received in years and know I can tolerate. But it may not be appropriate for this application.

As an academic question, what happens without any antibiotic treatment assuming the wound is clean and covered? What kind of infection would result? Recurrence of the same lesion, or something else entirely?

Thank you. My final question is whether I can safetly stop the Bactrim and switch after having taken a dose, and whether azithromycin is useful for a skin infection like this?