The pigment network appears as a delicate, regular grid of brownish lines over a diffuse light-brown background.
Histopathologically, the lines of the pigment network correspond to more or less pigmented and elongated rete ridges and the meshes of the network correlate to the dermal papillae. The appearance of the pigment network is thus determined by size and configuration of rete ridges.
The pigment network represents the dermoscopic hallmark of melanocytic lesions, independent of their biologic behavior. Remarkably, the assessment of pigment network alterations is helpful for differentiating between benign and malignant melanocytic proliferations, especially when they are confined to the epidermis and superficial dermis.
Typical pigment network
A typical pigment network, a common finding in Clark nevus, is characterized by a light- to dark-brown pigmented, regularly meshed and narrowly spaced network distributed more or less regularly throughout the lesion and usually thinning out at the periphery. Obviously, there are many variations on the theme of the typical pigment network reflecting the protean morphologic spectrum of Clark nevus. In addition, a delicate typical pigment network is nearly always found in lentigo simplex, solar lentigo, and often also in dermatofibroma.
Atypical pigment network
An atypical pigment network, a dermoscopic criterion with high specificity for the diagnosis of melanoma, is characterized by a black, brown, or gray, irregularly meshed network, distributed more or less irregularly throughout the lesion and usually ending abruptly at the periphery. The lines of an atypical pigment network are often thickened.