Hi, this is Dr Sathya. Thanks for your question and I will try my best to help you.
These abnormal skin areas you mentioned do not appear to be a primary neurological condition rather they appear to be some kind of skin condition. Skin conditions too can present with areas where there is no much sensation is felt or felt numb etc
While numbness can be very much a neurological symptom too, however when a neurological condition presents with numbness this is not the way it presents rather it will present in a much larger area than the ones you are having. For example if this is neurological then we see the whole limb is involved or a major portion of the limb is involved, but in your case only a localized patchy area are involved and such presentation is more in favor of some primary skin condition.
Some examples of neurological conditions that can present with numbness include neuropathies (peripheral nerve damage), MS (Multiple Sclerosis - a condition affects the brain and the spinal cord ) etc, and when these conditions present with skin numbness they involve much larger area on the skin than as in your case, and also there are generally other neurological symptoms other than the numbness alone as in your case.
Since this is going on for some time I do not see any serious condition to explain this skin condition, however if not done already then you may see a skin dr to get an opinion from them. If they feel that there is still some neurological possibility then you may see a neurologist too just as a precautionary measure. I am telling like this because I have not examined you so I cannot close the neurological possibility totally but my gut feeling is this skin condition you are having is not something neurological rather it is some kind of skin condition and one or otherway it does not sound anything serious in nature.
The above are my opinions & recommendations regarding the diagnosis of your numb areas on the skin, and please ask me if there are any further questions.
Thanks for the waiting!
All the best!
If you have any additional questions, concerns or clarifications then please let me know. And if you are satisfied with my answer please accept it so that I will be credited for my expertise, time and effort put in preparing this answer.