This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Diabetes Mellitus, Subject name: Medicine
The following lesion was noticed in a patient with history of involuntary weight loss. What is the diagnosis? 
Select and explain. 
A. Acanthosis nigricans, B. Leser-Trelat sign, C. Actinic keratosis, D. Interiginous candida
A: Acanthosis nigricans
Answer: A: Acanthosis nigricans 
Explanation: The image shows presence of asymmetric, velvety hyperpigmentation at the back of the neck of the patient suggestive of diagnosis of acanthosis nigricans. It is seen in patients with impaired glucose tolerance and internal malignancy. Choice B is seen in patients with internal malignancy and but has multiple pigmented skin lesions. Choice C is a is a crusty, scaly growth caused by damage from exposure to ultraviolet (UV) radiation. Choice D has red inflamed lesions and is hence ruled out.