This may be a hyperpigmentation reaction. Also, a contact dermatitis my be considered here. Have you been wearing anything around the neck or around the chest which could have triggered this reaction? Prior to the discoloration, have you noticed any redness or rash over the area? Is the rash itchy?
Based on the weight and height you have given me, your body mass index is 35 kg/m2 which is on the heavy side. I suggest that you try to maintain a healthy lifestyle and start to lose weight. Losing weight may help these dark discolorations disappear .
You may ask your primary physician about this so that the right diet may be planned for you. Also, exercise daily. Inform your doctor about this too. Do not engage in strenuous exercises right away. Start with the low impact ones such as swimming.
Do you sunbathe frequently or have tanning sessions frequently also?
Any underlying disease conditions such as diabetes or hypertension?
Any hormonal problems?
No its not itchy at all... I guess when I am in the sun sometimes it burns slightly. I dont go out in the sun alot...or tan. I don't have any diseases that I know about and no hormone problems. My family does have a history of high blood pressure which I do show signs of but haven't addressed it.