A) Alzheimer's disease
B) tuberculosis
C) diabetes mellitus
D) Grave's disease
E) melanoma
The answer is C. (Diabetes mellitus)
Although the majority of cases of acanthosis nigricans are benign and associated with obesity, the disease can represent the onset of malignancy as well as a variety of conditions related to insulin resistance.
Acanthosis nigricans has been reported in association with a number of malignancies, particular gastrointestinal cancers (e.g., gastric, hepatocellular) and lung cancer. The suspicion for malignancy increases in patients with extensive or rapidly progressive lesions, when there is mucous membrane involvement, or when there is prominent sole and palm disease.
The common finding in all non-malignancy associated cases of acanthosis nigricans is insulin resistance. This explains the relationship between this skin disorder and diseases such as diabetes mellitus, Cushing's syndrome, and hypothyroidism (most likely due to weight gain and subsequent insulin resistance), and with obesity.