Dermatoscopic findings of urticaria pigmentosa
Mastocytosis is a rare disease characterized by proliferation and accumulation of mast cells in various organs (skin, bone marrow, skeletal system, gastrointestinal tract, spleen, lymph nodes and liver). It is classified as cutaneous or systemic mastocytosis.
Actually, cutaneous mastocytosis is subclassified into three clinical variants: maculopapular cutaneous mastocytosis, diffuse cutaneous mastocytosis, and solitary mastocytoma. Furthermore, the maculopapular cutaneus mastocytosis is divided into three subtypes: papular/plaque variant, urticaria pigmentosa (UP) and eruptive macular telangiectasia perstans (TMEP).
Dermoscopy is a noninvasive technique designed to evaluate colour and structures of the epidermis, the dermoepidermal junction and the papillary dermis, which are not seen with the naked eye. One of its main applications is to classify melanocytic and non-melanocytic lesions.
Several algorithms have been designed to diagnose melanocytic lesions, and one of the main criteria is the presence of pigmented network. However, this dermoscopic structure is also seen in non-melanocytic lesions such as dermatofibroma, solar lentigo, seborrheic keratosis, accessory nipple, Kaposi’s sarcoma and even in the normal skin.
Recently, two authors reported the dermoscopic patterns of mastocytosis. The pigmented network was also described in urticaria pigmentosa, a subtype of maculopapular cutaneous mastocytosis.