The authors report a case of basaloid carcinoma involving the anus and rectum of a 57-year-old woman. Microscopically, the tumor showed unusual morphologic features strongly resembling a spiradenocylindroma because it consisted, in most parts, of basaloid cell nodules arranged in a jigsaw-puzzle fashion containing or surrounded by eosinophilic basal membrane material; in addition, there were intratumoral lymphocytes. The overlying squamous epithelium manifested dysplastic changes compatible with in situ squamous carcinoma that gradually became invasive and blended with basaloid cell islands; additionally, there were koilocytes in the squamous epithelium. A molecular biology study identified HPV-16 in the lesional tissue. Analysis of the CYLD gene did not prove any mutation.
From the *Sikl's Department of Pathology, Charles University, Medical Faculty Hospital, Pilsen, Czech Republic; †Department of Pathology, Medical Faculty Hospital, Martin, Slovak Republic and Bioptical Laboratory, Pilsen, Czech Republic.
Reprints: Dmitry V. Kazakov, MD, PhD, Sikl's Department of Pathology, Charles University, Medical Faculty Hospital, Alej Svobody 80, 304 60 Pilsen, Czech Republic (e-mail: firstname.lastname@example.org).