PMC4073032_01
Axial section of a contrast-enhanced computed tomography scan of the abdomen and pelvis showing the sigmoid tumor (marked with arrow)
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F1
A contrast-enhanced computed tomography of the abdomen and pelvis was performed which revealed a sigmoid tumor (Fig. 1).
Intraoperative photograph showing the perianal scar at the site of excised fistula and the perianal abscess (marked with arrows)
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F2
A day before the surgery he developed another perianal abscess (Fig. 2).
Photograph of the abdominoperineal resection specimen showing the perianal scar at site of the excised fistula, the perianal abscess and the sigmoid tumor (marked with arrows)
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F3
Surgery consisted of abdominoperineal resection (APR) with excision of the sigmoid mass, perianal mass and the scar site of excised fistula (Fig. 3).
(A) Sections showing moderately differentiated adenocarcinoma of the sigmoid (H& E x 100x); (B) and anal fistula tract lined by inflammatory granulation tissue (H& E x 40x); (C) with tiny foci of adenocarcinoma in the fistulous tract along with pools of extracellular mucin (H& E: 40x); (D) and high magnification showing similar tumour in anal fistula tract as in the sigmoid (H& E: 100x)
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F4
Pathological results of the sigmoid tumor revealed moderately differentiated adenocarcinoma with focal signet ring cell morphology up to subserosal fat without lymph node involvement of 12 lymph nodes dissected (T3N0M0) with MSI-H histology (Fig. 4 A). The perianal fistula tract (Fig. 4 B,C) also revealed moderately differentiated adenocarcinoma with extracellular mucin amidst acute inflammation. The histologic appearances of the two malignancies were similar (Fig. 4 A,D).
(A) Sections showing sigmoid adenocarcinoma immunopositive for cytokeratin 20; (B) while immunonegative for cytokeratin 7; (C) and perianal adenocarcinoma immunopositive for cytokeratin 20; (D) while immunonegative for cytokeratin 7
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F5
Both the sigmoid cancer and the perianal tumor were CK7- and CK20+ and showed a similar pattern (Fig. 5A-D).