Pop Quiz #159

The correct answer is D. Insulin resistance.

Acanthosis nigricans is characterized by velvety brown plaques most commonly seen on the neck and intertriginous skin.  It is most commonly associated with insulin resistance.  In the malignancy related form, the lips and palms may be involved.

Eruptive xanthomas are pink-yellow papules that arise on the extensor surfaces of extremities and the buttocks as a result of hypertriglyceridemia.  Hypertriglyceridemia may be the result of inherited hyperlipoproteinemias or due to medications such as isotretinoin.

Peripheral eosinophilia may be noted in a variety of atopic or allergic conditions including atopic dermatitis or drug eruptions.  Eosinophilia may also indicate parasitic infection.

Pretibial myxedema is characterized by indurated plaques of the anterior shins.  Mucin deposition is found on biopsy.  Pretibial myxedema is most commonly associated with Grave’s disease.

Petechiae and purpura are seen in the setting of low platelets.  Depending on the severity of thrombocytopenia the petechiae and purpura may occur spontaneously or in response to trauma.