I should have also said that the absence of ulceration suggests herpes isn't the cause, as you suggest yourself. However, if you have been at risk for herpes, such as sex with an infected partner, it might be a possibility despite the atypcial appearance.
HPV and genital warts generally are asymptomatic; sometimes warts can itch, but probably only when there is secondary infection. The most common overall cause of anal itching is nonspecific irritation called pruritus ani -- which doesn't help much, since it's just Latin for itchy anus. There probably are multiple causes, but simple irritation from feces probably is the main one. Also physical irritation, as you describe yourself. Yeast infection also is possible, generally a more frequent explanation in women than men. But the inflamed bump suggests it could be a pimple. On the slightly more serious side, perhaps you are on the verge of developing an anal fissure, or conceivably a small peri-rectal abscess. You don't say anything about your STD risks, but if they are substantial, then conceivably it is chlamydia, gonorrhea, or syphilis. But it doesn't sound typical for any of those.
The bottom line (no pun intended) is that you'll need to see a health care provider to know what's going on. If the symptoms are mild, you could try a soothing ointment, or even an over-the-counter steroid like hydrocortisone. But if more severe, or if the symptoms persist for more than a day or two after self treatment, see a health care provider for sure.
Good luck-- HHH, MD
Warts generally appear in a few weeks, but sometimes might not show up until 5 months or later. There are no data on HPV transmission comparable to the HSV data. However, HPV is highly transmissible, probably much more so than herpes. For example, among virgin university women without HPV who then become sexually active, 20% become HPV positive after having had only one lifetime sex partner, often after only a few episodes of sex.
If you have had 3 or more different sex partners in your lifetime, there is a 70-80% chance you have had HPV at least once. For practical purposes, genital HPV is inevitable and unavoidable in all sexually active people. Happily, the large majority of infections remain asymptomatic, go away by themselves, and do not lead to any serious health outcome.
Hi, thanks for the feedback. I consider myself at very low STD risk. I had the full range of classic STD tests in mid-September and have been with my single current partner since that time. (My tests were negative at that time as well and included the ones you mentioned in your reply). Two additional questions about HPV if you have time:
1. Is it true that if a person develops warts they will develop within a couple of months? If I had been exposed to HPV more than 5 months ago is it likely I would just now see a symptom?
2. You have mentioned in other threads the likelihood of contracting herpes or other stds in a monogamous relationship in which one person is infected and the other is not. Are there any percent data of similar transmission for HPV? Thanks!
Thank you again!