RESUMO
Syndromal acanthosis nigricans is associated with cellular resistance to the action of insulin and other endocrinopathies. In the insulin resistant state, increased insulin binds to the receptors of insulin-like growth factors (IGFs). IGFs are growth prompting peptides, which act as direct mitogens on cells containing the receptors. Through these actions, increased cellular growth and metabolism cause the skin lesions of acanthosis nigricans. Hyperandrogenism is also found in syndromal acanthosis nigricans patients. When associated with insulin resistance, these states are proportionally related. Increased insulin prompts the synthesis of androgen and conversely, increased androgen elevates the insulin resistance. We present three cases of syndromal acanthosis nigricans with hyperpigmented skin lesions and obesity. Laboratory findings demonstrated normal fasting blood suga levels with increased insulin and C-peptide levels and decreased insulin receptors. The oral glucose tolerance test was normal. We suggest that these patients were in an insulin resistant state. Skin biopsies from the axilla in all three cases showed hyperkeratosis, irregular acanthosis and upward projection of dermal papillae as finger like fashion. Thus all three cases represent syndromal acanthosis nigricans associated with an insulin resistant state based on clinical, histopathological, and laboratory findings. The three patients were treated with dietary control.