Pagetoid Spitz nevi: clinicopathologic characterization of a series of 12 cases

Background: Pagetoid Spitz nevus is an uncommon Spitz nevus variant characterized by a predominantly intraepidermal proliferation of single epithelioid melanocytes. Recognition of this variant is important to avoid misdiagnosis as melanoma.

Methods: We reviewed and characterized 12 pagetoid Spitz nevi diagnosed at a tertiary care institution over the past 25 years.

Results: All patients were female and average age at biopsy was 34 years. Clinically, 83% (10 out of 12) were located on an extremity and all were ≤ 6 mm in diameter. Histologically, pagetoid Spitz nevi were characterized by individual intraepidermal epithelioid melanocytes mostly confined to the lower half of the epidermis. Most displayed epidermal hyperplasia, eosinophilic bodies and melanocytes with minimal pleomorphism. All displayed melanoderma and at least mild dermal inflammation.

Conclusions: This represents the largest series of pagetoid Spitz nevi characterized to date. Although most clinicopathologic characteristics in our series correlated with those previously described, novel findings included occurrence in middle-aged adults, occurrence above the waist and demonstration of melanoderma in all lesions. Presence of dermal inflammation and melanoderma may contribute to atypical clinical appearance leading to biopsy despite their small clinical size. Recognition of these additional novel histologic features may aid dermatopathologists in distinguishing pagetoid Spitz nevi from melanoma.