Blue nevi are benign melanocytic lesions located in the deeper reticular dermis, consequence of failure of melanocytic migration into the dermal-epidermal junction from the neural crest. Lesions are usually asymptomatic and solitary, but may present in a multiple or agminated (grouped) pattern. The agminated subtype is formed when bluish-pigmented lesions cluster together in a well-defined area. Lesions can be flat or raised. We report the case of a patient who presented multiple bluish macules (1-3 mm in diameter) grouped on the left upper back. Dermoscopy and anatomic pathological examination were consistent with blue nevus.

Gianotti-Crosti syndrome is a rare disease characterized by acral papular eruption with symmetrical distribution. It is a benign and self-limited disease; the symptoms disappear after two to eight weeks, without recurrences or scars. Skin lesions are usually asymptomatic. Prodrome might occur, suggesting upper respiratory infection, or constitutional symptoms. Diagnosis is eminently clinical, and this disease is associated with viral infections. Due to its rarity and low occurrence in adolescents and adults, we report a case of Gianotti-Crosti syndrome of a teenager.