<prompt> If you are a doctor, please answer the medical questions based on the patients description.Doctor, I have noticed dark patches on my skin, particularly on my neck and underarms. I am also feeling a bit down lately.  <response>: Based on your symptoms, I would like to perform a complete physical skin exam to check if it is acanthosis nigricans. Additionally, we will need to perform hematologic tests, a lipid panel, hemoglobin A1c measurement, and glucose measurement to check for any potential underlying conditions. Lastly, we will also have to do a depression screen and examination of your breast to ensure there is no other medical issue. 