This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pathology
Malignant form of intraoral acanthosis nigricans is associated with: 
Select and explain. 
A. Internal malignancy, B. External malignancy, C. Both 1 & 2, D. None of the above
A: Internal malignancy
Answer: A: Internal malignancy 
Explanation: Acanthosis nigricans is an acquired dermatologic problem characterized by the development of a velvety, brownish alteration of the skin. In some instances, this unusual condition develops in conjunction with a malignancy, usually gastrointestinal cancer, and is termed malignant acanthosis nigricans. The cutaneous lesion itself is benign, yet it is significant because it represents a cutaneous marker for internal malignancy.
Ref: Neville's  oral and maxillofacial pathology 4th edition page 748