A Janus-Headed Polyp: Adenoma and Carcinoma with a Single Stalk

Figure 1 A 70-year-old patient was admitted to hospital due to lower gastrointestinal bleeding from a biopsy site in a large polyp in the sigmoid colon. A polypectomy was performed after placement of an Endoloop. Histopathological examination revealed a tubular villous adenoma and an adenocarcinoma, with the two tumors growing out of a single pedicle.

Figure 2 Microscopic examination of the first head showed that it was a highly differentiated adenocarcinoma with neoplastic glands in the muscularis mucosae (a), arising within an adenoma (b). There was a focus of invasion surrounded by desmoplasia (a). Periodic acid-Schiff, original magnification × 200 (a), × 16 (b).

Figure 3 The second head consisted of a tubulovillous adenoma with high-grade dysplasia. The adenoma consisted of dysplastic tubular crypts, as well as finger-like structures, and had a gland-within-gland appearance without intervening stroma. b The dysplastic epithelium, with enlarged and stratified nuclei, extending into the upper third of the cells, with loss of polarity. Hematoxylin-eosin, original magnification × 200 (a),× 16 (b).

Figure 4 The resection specimen shows a two-headed polyp growing out of a single stalk. The first head (the adenocarcinoma, I) measured 1.5 × 1.5 cm, the second head (the adenoma, II) was 1.0 × 1.0 cm, and the pedicle was 1.3 × 0.7 cm. So far as we are aware, this is the first description of an adenocarcinoma and an adenoma growing out of a single stalk. We have termed it ”Janus-headed” after the Roman god Janus, the double-faced god of entrances and exits, whose image was often placed in doorways and who symbolized things that have two sides - a good one and a bad one.