PMC2990122_01
The mass on the left buttock was 20 x 10 x 4 cm in diameter and its surface was cauliflower-shaped with profuse exudates and ulceration. The skin around the mass colored brownish to purplish and had ulcers likely penetrating to the mass.
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The mass on his left buttock was 20 x 10 x 4 cm in diameter, and its surface was cauliflower-shaped with profuse exudates and ulceration (Figure 1).
The mass invaded into coccygeal bone and the rear side of rectum (arrow).
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 Computed tomography (CT) and magnetic resonance imaging (MRI) (Figure 2) showed that the mass invaded into coccygeal bone and the posterior wall of the rectum.
Histologically, the tumor includes papilliform-acanthosis, a number of cancer pearls, and individual cell keratinization.
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Under high magnification, the tumor included papilliform-acanthosis, a number of cancer pearls and individual cell keratinization (Figure 3).
A washy red smooth nodule was noticed from the beneath of tumor after chemoradiation therapy. It was adjneent to the ulceration.
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It was adjneent to the ulceration (Figure 4).
According to the first extent of tumor, buttock skin was excised together with sacrococcyx, and rectum. Reconstructive surgery by musclocutaneous flap of abdominal rectus muscle and colostomy was performed.
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The perineum was reconstructed with a pedicled musclocutaneous flap using the right abdominal rectus muscle, and sigmoid colostoma was created (Figures 5 and 6).
The excised specimen. The buttock skin, sacrococcyx and rectum were excised together.
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The perineum was reconstructed with a pedicled musclocutaneous flap using the right abdominal rectus muscle, and sigmoid colostoma was created (Figures 5 and 6).
The nodule appeared after chemoradiation therapy showed papilliform structure with invaginate to the dermis and the wall was consisted with two layers of epithelial cells. The outer layer of the epithelium was composed of cuboidal cells and the inner layer of columnar cells. Many plasma cells infiltrated to the interstitial area.
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Many plasma cells infiltrated to the interstitial area (Figures 7(a) and 7(b)).