This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Disorder of Metabolism & Connective Tissue, Subject name: Medicine
What is the most likely diagnosis in a patient with generalized weakness and this finding? 
Select and explain. 
A. Lichen planus pigmentosus, B. Smoker's melanosis, C. Cushing's disease, D. Diffuse melanosis cutis
D: Diffuse melanosis cutis
Answer: D: Diffuse melanosis cutis 
Explanation: Answer D. Diffuse melanosis cutisDiffuse melanosis cutis is the correct answer. It is a rare presentation of malignant melanoma with progressive discoloration of the skin. Diffuse melanosis cutis is typically associated with poor prognosis.