Anetodermic pilomatricoma: molecular characteristics and trauma in the development of its bullous appearance.

Pilomatricoma is a common benign neoplasm of the skin characterized by a solid cutaneous nodule of hair matrix origin. The anetodermal or lymphangiectatic variant of pilomatricoma is rare, and its bullous appearance is often associated with attenuated collagen and elastic fibrils and dilated lymphatic vessels in the overlying dermis. However, the tumors of anetodermic pilomatricoma have never been characterized at the molecular level, and the exact mechanism for their development is unknown. In this study, we evaluated histological and molecular features of a bullous pilomatricoma along with 5 control tumors and determined that tumors of both anetodermic and control pilomatricoma comprise similar molecular features, such as nuclear lymphoid enhancer binding factor 1 (LEF1) localization and the expression of keratins. In addition, we associated the development of the anetodermic pilomatricoma with mechanical trauma, scar tissue formation, and increased numbers of blood and lymphatic vessels. This study suggests that the development of the anetodermic form of pilomatricoma is unlikely to be associated with the intrinsic properties of the tumor but with the mechanical trauma that disrupts the dermal integrity and vascular microenvironment.