[Sebaceous hamartoma of Jadasshon: trichoblastoma mimicking basal cell carcinoma?]

The sebaceous hamartoma of Jadassohn is a congenital skin malformation usually appeared at birth or in early childhood. Many authors support the notion that early complete surgical excision is necessary to prevent the development of malignant neoplasms (especially basal cell carcinoma) after puberty. On the contrary, others in recent large series suggest that it is an histological misdiagnosis: the basal cell-carcinoma is in fact a trichoblastoma, basaloïd neoplasm, but non-malignant one. We have also asked anatomopathologist for proofreading slide previously described as basal cell carcinoma to research unknown trichoblastoma. During the period, 1982 to 1999, 80 sebaceous hamartoma of Jadassohn were excised and 19 basal cell carcinoma were found. The basal cell carcinoma diagnosis has been confirmed in two cases only. The others were pigmented trichoblastomas. So, trichoblastoma is the most common basaloïd tumor developed in sebaceous of hamartoma Jadassohn. Nevertheless, we should recommend surgical excision during the childhood because of best elasticity of tissue, especially on the scalp where it's mostly localized.