I have a small patch of itchy skin at the base of my left middle finger. There are 2 little brown dots of pigment in the skin just deep of the surface but superficial to the dermis itself. When I run my finger over the area it feels like there is a bump there, almost like a callous, but I don't engage in any activities that would cause a callous at the base of my finger like this. The region affected is the palm-side of the finger roughly 1 cm up from the interface between the finger and the hand, roughly midway between the base of the finger and the articulation of the first knuckle, i.e. the proximal phalange of the middle finger.

This is the second time I've had this condition. The first time I got it, there were a lot of clear, lumpy formations that looked like tiny blisters, and the whole thing taken together looked reminiscent of a plantar wart, so I treated it with an OTC application of salicylic acid and a bandage. This seemed to clear things up well after several days. It's been a month or two since then and now I again have a brown itchy spot, though this time with no clear bumps/blisters.

I'd be happy to attach a photograph if that would be useful in diagnosis. I'm aware there are dozens of reasons for brown spots or itchy bumps on the hand. I do not think this is a nevus as it is a very small brown spot. And while it is irregular in shape, I don't think it is anything as horrific as skin cancer, though melanoma can manifest in some weird ways. I have not had a particularly notable history of sun exposure: I've only been sunburned once or twice in my life and typically put high-SPF sunblock on any time I'm going to be outside for more than a a few minutes.