Light microscopy of a skin naevus sometimes referred to as a mole. The naevus shows a abnormal proliferation of pigment-producing cells melanocytes. This is a deep penetrating naevus with extensive growth into the dermis. The fine cytoplasmic extensions of many thousands of melanocytes are filled with dark pigment granules giving a dense network pattern of pigment. Naevi are usually benign . The macroscopic appearance may give the classification as a blue naevus. Magnification x30 when printed at 10 cm.