Pigmented reticular structures in basal cell carcinoma and collision tumours.

Background: The dermatoscopic diagnosis of basal cell carcinoma (BCC) is based on well-known specific criteria. Despite the fact that a pigment network is considered a negative feature for the diagnosis of BCC, its detection in a BCC context has been reported in 2.8% of cases.

Objectives: To determine whether pigment networks or network-like structures might represent a pitfall for the correct diagnosis of BCC.

Methods: Dermatoscopic images of 412 histopathologically proven BCCs were analysed retrospectively.

Results: Pigment network or network-like structures were detected in 14 of 412 (3.4%) BCCs. Nine of 14 BCCs presented a typical pigment network, due to the association of a BCC lesion with a naevus, solar lentigo or actinic keratosis; two BCCs located on the face showed a pseudonetwork, and three of 14 lesions displayed a network-like structure characterized by light-brown irregularly meshed short linear structures, histopathologically related to a hyperpigmentation of the basal layer of the epidermis.

Conclusions: The presence of a pigment network in the context of a BCC is uncommon, and it usually reflects the association of BCC with a solar lentigo, naevus or a specific location of the lesion on photodamaged skin.