Contiguous squamous proliferations in syringocystadenoma papilliferum: A retrospective study of 14 cases.

Syringocystadenoma papilliferum with contiguous squamous proliferation is underreported, and most commonly displays verrucous hyperplasia. The premalignant and malignant contiguous squamous proliferations likely arise from syringocystadenoma papilliferum while the hyperplastic contiguous squamous proliferations likely arise from the adjacent epidermis. Relationship with high-risk human papilloma virus is unlikely. However, further molecular analysis of larger number of cases is required to establish the pathogenesis.