Rippled-pattern sebaceous trichoblastoma

Background: There is a large spectrum trichoblastoma; of which, several his tologic variants have been described including a rippled-pattern variant. T hree cases of rippled-pattern trichoblastoma are described which also exhib ited definitive foci of sebaceous differentiation Methods: Three cases were retrieved from the archives of the Dermatopatholo gy Laboratory at the University of California Irvine (Orange, CA, USA). All specimens were stained with hematoxylin and eosin (H&E). In addition, sect ions were submitted for immunohistochemical studies with epithelial membran e antigen (EMA). Results: Al three biopsies were composed of well-circumscribed multiple var iously sized tumor lobules present in the upper to deep dermis comprised of with rounded or slightly elongated basaloid cells with scant eosinophilic cytoplasm. The lobules were separated by a slightly hyalinized stroma, The unique finding present in all three specimens was a peculiar arrangement of the basaloid cells in linear rows parallel to one another. This gave the t umors a rippled pattern similar to the palisading of nuclei of Verocay bodi es seen in schwannomas. In addition all three biopsies showed definite seba ceous differentiation. Conclusions: Three additional cases of rippled-pattern trichoblastoma are p resented. All three were located on the scalp and showed additional feature s of foci of sebaceous differentiation, No associations with Muir-Torre Syn drome were found in these patients. Because this appears to be a distinct v ariant within the large spectrum of trichoblastoma, the term rippled-patter n sebaceous trichoblastoma is suggested.