Board Review: Cutaneous Signs of Internal Malignancy

Overview / Definition Cutaneous signs of internal malignancy refer to various skin manifestations that may indicate the presence of an underlying cancer. These signs can range from benign-appearing lesions to more distinctive cutaneous markers, which often serve as important clues in diagnosing internal malignancies. Epidemiology The prevalence of cutaneous signs associated with internal malignancies varies based on the type of cancer and the population studied. Certain skin manifestations are more commonly associated with specific malignancies: **Acanthosis nigricans**: Frequently associated with gastric adenocarcinoma. **Dermatologic paraneoplastic syndromes**: Occur in approximately 20-30% of patients with malignancies. **Keratoacanthomas**: May arise in patients with squamous cell carcinoma. Pathophysiology / Mechanism The mechanisms by which internal malignancies manifest on the skin are diverse and may include: **Tumor secretion of hormones or cytokines** that affect skin biology. **Immune-mediated responses** that result in skin changes. **Direct invasion** of skin structures by malignant cells. Clinical Presentation Cutaneous signs of internal malignancy can present in various forms, which may include: **Acanthosis nigricans**: Velvety thickening of the skin, commonly seen in the neck and axilla. **Leser-Trélat sign**: Sudden eruption of multiple seborrheic keratoses, often associated with underlying malignancies. **Erythema gyratum repens**: Characterized by concentric rings of erythema, associated with lung cancer. **Xeroderma pigmentosum**: Increased skin malignancies due to impaired DNA repair mechanisms. Diagnosis / Workup Diagnosis of cutaneous signs of internal malignancy involves: **Clinical evaluation**: A thorough history and physical examination are crucial. **Biopsy**: Skin lesions may require histopathological examination to rule out malignancy. **Imaging studies**: CT or MRI scans may be indicated to assess for internal tumors. Treatment / Mana