Morphological and flow-cytometric characterization of a trichilemmoid carcinoma cell line in vitro.

A cell line derived from a trichilemmoid carcinoma of a 85-year-old male was established in vitro and maintained in culture for 14 months. From the explant culture to the second passage, the tumour cells propagated slowly. After 6 months (third passage) faster growth behaviour was noticed. In culture the neoplastic cells continued synthesizing abundant glycogen. The DNA histogram of original neoplastic cells revealed a seemingly normal unimodal DNA distribution. The tumour DNA remained apparently stable during the subsequent months in culture. However, after 6 months in culture, flow cytometry disclosed a spontaneous shift in nuclear DNA content. This study enabled us to establish in vitro the malignant properties of the tumour and strongly suggested that it was derived from trichilemmal cells.