Patient Care Hematology & Oncology - October 2007 - (Page 24)

I Dermatology Case Challenge Acanthosis nigricans This disorder is most likely caused by factors that stimulate epidermal keratinocyte and dermal fibroblast proliferation. In the benign form, the factor is probably insulin or an insulin-like growth factor that incites epidermal cell proliferation. In malignant acanthosis nigricans (AN), which is quite rare, the stimulating factor is hypothesized to be a substance secreted either by the tumor or in response to the tumor. Exogenous medications have also been implicated as etiologic factors. Obesity is closely associated with AN. Patients with the benign form of it have few to no complications of their skin lesions. However, many of them have an underlying insulin-resistant state that is the cause of their condition. The severity of the insulin resistance is highly variable and can range from an incidental finding on routine blood studies to overt diabetes mellitus. The severity of skin findings may parallel the degree of insulin resistance, and a partial resolution may occur with treatment of the insulinresistant state. Insulin resistance is the most common association of AN in the younger population. Malignant AN is associated with significant complications because the underlying malignancy is often an aggressive tumor. Average survival time of patients with signs of malignant AN is approximately 2 years. In older patients with new-onset AN, most have an associated internal malignancy. There is no racial predilection. The lesions of malignant AN are clinically indistinguishable from the benign forms. AN is much more common in people with darker skin pigmentation. The prevalence in decreasing order is African Americans, Hispanics, Native Americans, and Caucasians. Male and female incidence is similar. Lesions of benign AN may present at any age, although they are more common in adults. Malignant AN occurs most frequently in the elderly. Patients usually present with an asymptomatic area of darkening and thickening of the skin; pruritus is uncommon. Lesions begin as hyperpigmented macules and patches and progress to palpable plaques. Skin findings of AN can precede, be concurrent with, or occur subsequent to diagnosis of malignancy, in equal proportions. AN is characterized by symmetrical, hyperpigmented, and velvety plaques that may occur in almost any location but most commonly appear on the intertriginous areas of the axillae, groin, and posterior neck. The posterior neck is the most commonly affected site in children (7% of children). Skin tags, as in this patient, often are found in and around the affected areas. The definitive cause of AN has not yet been determined. Obesity-associated AN (pseudoacanthosis nigricans) is the most common type. Lesions can appear at any age, and the dermatosis is weight dependent, with lesions completely regressing in some patients with weight reduction. Insulin resistance is often present. Syndromic AN has been associated with endocrinopathies (eg, polycystic ovary syndrome, hyperthyroidism or hypothyroidism, 24 PATIENT CARE HEMATOLOGY & ONCOLOGY www.patientcareonline.com http://www.patientcareonline.com

Table of Contents Feed for the Digital Edition of Patient Care Hematology & Oncology - October 2007

Patient Care - Hematology & Oncology - October 2007 Research Digest Contents Information for Authors Medicine in the News Strategies for Bridge Anticoagulation Therapy How to Integrate the New Cervical Cancer Guidelines into Practice Dermatology Case Challenge Clinical Clips Classified Advertising

Patient Care Hematology & Oncology - October 2007

For optimal viewing of this digital publication, please enable JavaScript and then refresh the page. If you would like to try to load the digital publication without using Flash Player detection, please click here.