Hedgehog pathway mutations are involved in the pathogenesis of plaque-type trichoblastoma: A report of two cases

We present two cases of plaque-type trichoblastoma with atypical foci. A rare variant of trichoblastoma is the plaque variant, which is characterized by poor circumscription and locally infiltrative growth pattern. These lesions mostly require multiple stages of Mohs micrographic surgery. Debate still exists whether this variant should be considered as a benign entity or as low-grade malignant counterpart of trichoblastoma. In this report we describe two cases of plaque-type trichoblastoma with atypical foci, which harbored somatic mutations in the Hedgehog pathway, thus should be acknowledged as intermediate malignancies. In addition, extensive molecular workup of both the trichoblastic and atypical component in sequential lesions in the same patient was performed.

Automated summary

We present two cases of plaque-type trichoblastoma with atypical foci, which are characterized by poor circumscription and locally infiltrative growth pattern. These lesions mostly require multiple stages of Mohs micrographic surgery. In this report, we describe two cases of plaque-type trichoblastoma with atypical foci, which harbored somatic mutations in the Hedgehog pathway, thus should be acknowledged as intermediate malignancies.