RESUMEN
BACKGROUND: Hyperplasia-associated cutaneous paraneoplasia is an important differential diagnosis in everyday clinical practice. An early diagnosis of the underlying tumor disease can significantly improve the patient's prognosis. PATHOGENESIS: Hyperplasia is probably mainly cytokine-mediated. The primary tumor and/or the metastases release growth factors and transcription factors which, via epidermal growth factors, lead to hyperproliferation of keratinocytes. ACANTHOSIS NIGRICANS MALIGNA: Symmetrical mainly intertriginous hyperpigmentation with partially verrucous hyperplasia and lichenification mostly in association with gastric adenocarcinoma. Special forms are florid cutaneous papillomatosis and tripe palms. Pseudoacanthosis nigricans is to be distinguished (metabolic and hormonal disorders). LESER-TRéLAT SYNDROME: Eruptive occurrence of seborrheic keratosis associated with visceral tumors. ACROKERATOSIS BAZEX: Erythema and scaling initially at the bridge of the nose, ear helix and acra with later spread, associated with tumors of the upper aerodigestive system. It should be clinically differentiated from psoriasis. THERAPY: The treatment of the primary tumor is decisive, which also leads to a decrease of cutaneous symptoms. Reappreance suggests tumor recurrence.