The reticular pattern, the most common global feature in melanocytic lesions in man, is characterized by a pigment network covering most parts of a given lesion. Basically, the pigment network appears as a grid of thin brown lines over a diffuse light brown background. The manifold modifications of the pigment network may vary with changes in the biologic behavior of melanocytic skin lesions and thus special interest will be paid to these variations.
The reticular pattern represents the dermoscopic hallmark of benign acquired melanocytic nevi in general and of thin melanomas in particular. A pigment network, however, is nearly always found in lentigo simplex, the precursor lesion of acquired melanocytic nevi (Clark nevus), as well as in solar lentigo, the precursor lesion of seborrheic keratosis. Moreover, a delicate pigment network is also frequently seen in dermatofibroma.
Pseudonetwork of the face
This type of pigment network is due to the particular anatomy of the facial skin that is devoid of rete ridges and is characterized by closely situated follicular infundibula. Thus, a diffuse pigmentation of the epidermis or the papillary dermis in facial skin reveals a peculiar pigment network, also called pseudonetwork of the face, that dermoscopically appears to be composed of round, equally sized meshes corresponding to the pre-existing follicular ostia. The recognition of the pseudonetwork of the face actually has no diagnostic significance, because it is found in solar lentigo, in the reticulated type of seborrheic keratosis but also in dermal nevus of the face (Miescher nevus) and in melanoma in situ on severely sun-damaged skin (lentigo maligna). The distinction between these entities requires additional subtle criteria that will be addressed later.