Spitz nevus (spindle and epithelial cell nevus) is a benign melanocytic nevus that classically appears as a < 5-6 mm dome-shaped, symmetric, smooth, pink to red papule on the head, neck, or extremities. In adults, these lesions may appear as deeply pigmented, red-brown, or dark brown in color.

Since its initial description by Sophie Spitz in 1948, the importance of this lesion type has resided in its distinction from melanoma. While the classic Spitz nevus, as discussed here, can generally be distinguished from frank melanoma, there is also a spectrum of melanocytic proliferations with a spitzoid appearance and some atypical features (sometimes referred to as atypical Spitz tumor or AST) that fall somewhere in between and are difficult to classify.

Classic Spitz nevi are asymptomatic. Spitz tumors present commonly in patients younger than 30 years (76% of tumors) and often in those younger than 15 years (40% of tumors). The majority of lesions are solitary, but, rarely, they can be multiple and widespread (eruptive disseminated) or localized (agminated) in one area.

Spitz proliferations with atypical features, including benign ASTs and malignant Spitz melanomas, may prove difficult to differentiate. Diagnosis and management can be often be controversial, as the malignant potential of ASTs continues to be debated. Late adolescent age or older, diameter > 1 cm, ulceration, subcutaneous fat involvement, and mitoses are all features that increase the risk of metastasis in lesions categorized as ASTs.

Related topic: agminated nevus