| Literature DB >> 28690772 |
Andrew M Aneese1, Vinayata Manuballa1, Mitual Amin1, Mitchell S Cappell1.
Abstract
An 87-year-old-man with prostate-cancer-stage-T1c-Gleason-6 treated with radiotherapy in 1996, recurrent prostate cancer treated with leuprolide hormonal therapy in 2009, and bladder-urothelial-carcinoma in situ treated with Bacillus-Calmette-Guerin and adriamycin in 2010, presented in 2015 with painless, bright red blood per rectum coating stools daily for 5 mo. Rectal examination revealed bright red blood per rectum; and a hard, fixed, 2.5 cm × 2.5 cm mass at the normal prostate location. The hemoglobin was 7.6 g/dL (iron saturation = 8.4%, indicating iron-deficiency-anemia). Abdominopelvic-CT-angiography revealed focal wall thickening at the bladder neck; a mass containing an air cavity replacing the normal prostate; and adjacent rectal invasion. Colonoscopy demonstrated an ulcerated, oozing, multinodular, friable, 2.5 cm × 2.5 cm mass in anterior rectal wall, at the usual prostate location. Histologic and immunohistochemical analysis of colonoscopic biopsies of the mass revealed poorly-differentiated-carcinoma of urothelial origin. At visceral angiography, the right-superior-rectal-artery was embolized to achieve hemostasis. The patient subsequently developed multiple new metastases and expired 13 mo post-embolization. Comprehensive literature review revealed 16 previously reported cases of rectal involvement from bladder urothelial carcinoma, including 11 cases from direct extension and 5 cases from metastases. Patient age averaged 63.7 ± 9.6 years (all patients male). Rectal involvement was diagnosed on average 13.5 ± 11.8 mo after initial diagnosis of bladder urothelial carcinoma. Symptoms included constipation/gastrointestinal obstruction-6, weight loss-5, diarrhea-3, anorexia-3, pencil thin stools-3, tenesmus-2, anorectal pain-2, and other-5. Rectal examination in 9 patients revealed annular rectal constriction-6, and rectal mass-3. The current patient had the novel presentation of daily bright red blood per rectum coating the stools simulating hemorrhoidal bleeding; the novel mechanism of direct bladder urothelial carcinoma extension into rectal mucosa via the prostate; and the novel aforementioned colonoscopic findings underlying the clinical presentation.Entities:
Keywords: Bladder cancer; Cancer spread; Colonoscopy; Lower gastrointestinal bleeding; Rectum penetration; Transitional cell; Uroepitheilal; Urothelial
Year: 2017 PMID: 28690772 PMCID: PMC5483421 DOI: 10.4253/wjge.v9.i6.282
Source DB: PubMed Journal: World J Gastrointest Endosc
Direct extension of bladder urothelial carcinoma to rectum
| 1. 87-year-old man | Nineteen years PTA underwent external beam radiotherapy and leuprolide hormonal therapy for prostate cancer stage T1c Gleason 6. Five years PTA underwent Bacillus Calmette-Guérin immunotherapy and adriamycin chemotherapy for bladder urothelial carcinoma | Painless, bright red blood coating stools for 5 mo. Rectal exam: Bright red blood per rectum and large, hard, fixed, multinodular, “prostate” mass. Hemoglobin = 7.6 g/dL | CT angiography: Mass containing air-fluid cavity replacing prostate, with rectal invasion. Colonoscopy: Ulcerated, friable, oozing, multinodular, hemorrhagic, 2.5 cm × 2.5 cm mass on anterior rectal wall, just proximal to dentate line | Rectum: Poorly differentiated carcinoma of urothelial origin | Abdominopelvic angiography: Successful right-superior-rectal-artery embolization using embolospheres | Stopped bleeding for 3 mo. Subsequently rebled. Underwent palliative colostomy for the rebleeding. Died 13 mo after diagnosis of rectal lesion | Current report |
| 2. 64-year-old man | Sixteen month PTA, underwent radical cystectomy, left nephroureterectomy, and right ureterocutaneostomy for Grade 3 urothelial carcinoma Stage pT3aN0. 11 mo PTA, received 3 courses of MVAC chemotherapy for lymph node metastases | Anorexia, tenesmus | Abdominopelvic CT: Focal, annular thickening of rectal wall | Rectum: Urothelial carcinoma | Fecal diversion | Died 2 mo later | Katayama et al[ |
| 3. 60-year-old man | Prior high grade bladder urothelial carcinoma | Anal pain, fatigue, weight loss, and anorexia. Rectal exam: Hard, fixed, annular, constrictive mass, 6 cm from anal verge. Hemoglobin = 11.6 g/dL | Pelvic CT: Mass posterior to bladder. Perirectal wall thickening | Rectum: Grade 4 urothelial carcinoma | Chemotherapy with VP-16 and cisplatin in 3 mo cycles and external beam RT | Died 9 mo after initiating RT | Stillwell et al[ |
| 4. 58-year-old man | Two year PTA underwent partial cystectomy for grade 3 N0 bladder urothelial carcinoma | Anorexia, weight loss, fatigue, straining with bowel movements, narrow-caliber stools, rectal pain, and tenesmus for several months. Rectal exam: hard, annular, constrict-ing lesion with a narrowed lumen, at 8 cm from anal verge | Pelvic CT: Large mass encircling rectum, lytic lesion in third lumbar vertebra, and bilateral hydronephrosis. Proctoscopy: Constricting lesion with normal overlying mucosa, suggestive of extrinsic compression. Exploratory laparotomy: Hard mass extending from posterior bladder wall, obliterating rectovesical pouch, and encompassing rectum | Rectum: Biopsy during proctos-copy showed normal mucosal tissue. Transrectal (deep) and transperineal biopsy: Poorly differentiated grade 3 urothelial cancer | Sigmoid loop colostomy, RT to pelvis and lumbar spine, followed by single dose of cisplatin | Died 3 mo later from liver metastasis | Stillwell et al[ |
| 5. 73-year-old man | Three years PTA underwent radical cystoprostatectomy, with clear margins, and ileal loop urinary diversion for Stage pT3a N0 bladder urothelial carcinoma. At that time, biopsy also demonstrated areas of adenocarcinoma and signet ring cell carcinoma | Diarrhea, rectal pain, fatigue, weight loss, and fecal incontinence for 1 mo. Physical exam: Thin elderly male, bilateral lower extremity edema. Rectal exam: rectal stenosis 1 cm from anal verge. Guaiac negative stool | Abdominopelvic CT: annular rectal mass. Exploratory laparoscopy: Solid pelvic tumor adherent to sacrum | Rectum: Urothelial cancer invading muscularis propria of rectal wall | Diverting loop colostomy | Chemotherapy planned, but patient developed lower extremi- ty ischemia, requiring leg amputation. Died shortly thereafter | Langenstroer et al[ |
| 6. 76-year-old man | Underwent left nephroureter-ectomy. 1 mo PTA underwent right ureteral diverting cutaneostomy for grade 3 bladder urothelial carcinoma. Bladder mass firmly attached to pelvic wall and to thickened lateral pedicles | Symptoms of rectal obstruction. Rectal exam: Stenosis with intact rectal mucosa | Pelvic CT: Annular thickening of rectal wall and thickened lateral pedicles, bilaterally | Rectum: Urothelial carcinoma | Diverting colostomy and unspecified immunotherapy | Died 5 mo later | Kobayashi et al[ |
| 7. 66-year-old man | No prior oncologic history | Rectal exam: Severe rectal stenosis with intact rectal mucosa | Abdominopelvic CT: Thickened bladder and rectal walls, bilateral hydronephrosis. Colonoscopy: Narrow rectal lumen with edematous mucosa, suggesting extrinsic compression | Rectum: Grade 3 urothelial carcinoma | Ileal-conduit and colostomy | Died 3 mo after surgery | Kobayashi et al[ |
| 8. 51-year-old man | 1 mo PTA underwent ureterocutaneostomy for unresectable grade 3 bladder urothelial carcinoma attached to pelvic wall, causing bilateral hydronephrosis | Thin stools. Rectal exam: Narrow rectal lumen | Pelvic CT: Annular constriction of rectum | Rectum: Grade 3 urothelial carcinoma | Diverting colostomy and one course of M-VAC chemotherapy | Died 10 mo after surgery | Kobayashi et al[ |
| 9. 74-year-old man | Eleven months PTA underwent radical cystectomy for grade 3 urothelial carcinoma of bladder | Continuous watery rectal discharge and thin stools | Barium enema: Stenosis of lower rectum Pelvic MRI: Thickened rectal mucosa and muscle layer without evident tumor | Rectum: Grade 3 pT3a urothelial carcinoma | Colostomy, MVAC chemotherapy, and radiation | Died 7 mo after presentation | Ito et al[ |
| 10. 54-year-old man | Underwent radical cystoprostatectomy with neobladder for grade 3 bladder urothelial carcinoma | Presumed refractory ulcerative proctitis | Pelvic MRI: Circumferential thickening of rectum. Endoscopy: Circumferential rectal wall thickening 11 cm from anal verge. EUS: Circumferential hypoechoic infiltrate extending through all rectal wall layers | Rectum: Urothelial carcinoma | Chemotherapy | NR | Gleeson et al[ |
| 11. 55-year-old man | Underwent radical cystoprostatectomy with neobladder for grade 3 bladder urothelial carcinoma | Constipation | Abdominopelvic CT: No evident metastasis Endoscopy: Circumferential rectal wall thickening with stricture 16 cm from anal sphincter EUS: Diffuse circumferential thickening of rectal wall | Rectum: urothelial carcinoma | Chemotherapy | NR | Gleeson et al[ |
| 12. 60-year-old man | Underwent radical cystoprostatectomy with neobladder, for grade 3 urothelial cancer of bladder | Constipation | Abdominopelvic CT: Abnormal perirectal lymph nodes. Endoscopy: Circumferential rectal wall thickening. EUS: Diffuse circumferential thickening of all layers of rectal wall with several hypoechoic lymph nodes in extraluminal space | Rectum: Urothelial carcinoma | Chemotherapy | NR | Gleeson et al[ |
CT: Computed tomography; GI: Gastrointestinal; M-VAC: Methotrexate, vinblastine, Adriamycin; NR: Not reported; PTA: Prior to admission; RT: Radiation therapy; MRI: Magnetic resonance imaging.
Metastases of urothelial bladder carcinoma to the colorectum
| 1. 63-year-old man | Ten months PTA underwent radical cystectomy and MVAC chemotherapy for bladder urothelial carcinoma | Painless jaundice, 5-kg weight loss, and constipation for 2 wk. Physical exam: mild right upper quadrant tenderness. Laboratory: Elevated liver function tests | Abdominopelvic CT: Concentric thickening of rectal wall; bile duct hilar stricture with diffuse intrahepatic ductal dilation. MRI: Diffusely thickened common hepatic duct with extension into secondary branch ducts suspicious for cholangiocarcinoma. Colonoscopy: Concentric rectal constriction blocking colonoscopic intubation. ERCP: Strictures of common hepatic and right intrahepatic ducts; obstructed left intrahepatic duct | Rectum and hepatic duct: Micropapillary variant of transitional cell (urothelial) carcinoma | Rectal tumor: RT with external beam and brachy-therapy. Hepatic tumor: Polyethylene stent placed in intrahepatic bile duct. RT is planned | Alive at 4 mo | Hong et al[ |
| 2. 55-year-old man | Fifteen months PTA underwent TURBT and 6 wk of mitomycin C, followed by 4 rounds of gemcitabine and cisplatin chemotherapy for high grade urothelial carcinoma of bladder with iliac lymph node chain involvement. Six months PTA underwent radical cystoprostatectomy with neobladder creation and pelvic lymphadenectomy | Worsening constipation, abdominal distention, anorexia, and dyschezia. Rectal exam: palpable mass 3 cm from anal verge | Abdominopelvic CT: Pelvic and omental nodules. PET: Increased uptake at these nodules. Flexible sigmoidoscopy: 3 cm wide rectal lesion near anal verge | Rectum, omentum, other pelvic structures: Urothelial carcinoma | Diverting loop colostomy | Brain and lung metastases | Asfour et al[ |
| 3. 77-year-old man | Eleven years PTA underwent resection of papillary bladder urothelial carcinoma. Eight years PTA underwent TURBT and RT for recurrence. Underwent periodic cystoscopies and bladder biopsies thereafter | Progressive constipation, weight loss, and malaise | Barium enema: barium could not pass beyond sigmoid colon. Laparotomy: Sigmoid colon obstructed due to adherent tumor of terminal ileum and cecum | Sigmoid, right-transverse colon, cecum, ileum, appendix, omentum: Urothelial carcinoma | Ileotransverse colostomy and loop colostomy of descending colon | NR | Aigen et al[ |
| 4. 60-year-old man | Five months PTA underwent radical cystectomy with ileal conduit for invasive bladder urothelial carcinoma | Painless hematochezia. Rectal exam: Red blood in rectal vault. No externally visible or palpable hemorrhoids. Hemoglobin declined from 11.6 g/dL to 8.7 g/dL | Necrotic pelvic lesions suspicious for metastases | Splenic flexure: Urothelial carcinoma | None | Refused treatment. Transferred to hospice | Kumar et al[ |
| 5. 57-year-old man | Five years PTA underwent total cystectomy for bladder urothelial carcinoma. One year PTA underwent lymph node resection, RFA, bone cement injection, and chemotherapy for left obturator lymph node and several pulmonary and left pelvic bone metastasis. Five months PTA underwent RT for regrowth of left obturator lymph node metastasis | Massive melena, HR = 120 beats/min, BP = 76/39 mmHg, Hemoglobin = 9.2 g/dL | Abdominopelvic CT: Malignant lymph node invading sigmoid colon, with pseudoaneurysm of mesenteric artery supplying sigmoid Colonoscopy: Large, oozing, ulcerated colonic tumor | Sigmoid colon: NA | Pelvic angiogram: 10 mm × 8 mm pseudoaneurysm of left inferior gluteal artery successfully embolized using microcoils and vasopressin | Alive at 5 mo | Kakizawa et al[ |
| 6. 83-year-old man | No prior oncologic history | Diarrhea and weight loss during prior 6 mo. Rectal exam: Mass 3 cm from anal verge | Abdominopelvic CT: Thickened right posterior wall of bladder, circumferential rectal wall thickening, and infiltrative lesions in multiple skeletal muscles Proctoscopy: Mass 3 cm from rectal verge | Rectum and skeletal muscles: Poorly differentiated urothelial carcinoma | Chemotherapy (regimen not specified) | NR | Ying-Yue et al[ |
| 7. 54-year-old man | Two years PTA underwent radical cystectomy and ileal neobladder reconstruction for grade 3 bladder urothelial carcinoma | Change in bowel habits | Abdominopelvic MRI: Circumferential thickening and high-grade stenosis of rectal wall. Sigmoidoscopy: Luminal narrowing with erythematous and edematous folds. EUS: Hypoechoic, circumferential, rectal wall thickening, mimicking primary rectal cancer. No evident direct cancer extension from bladder | Rectum: Urothelial carcinoma | Chemotherapy (regimen not specified) | NR | Yusuf et al[ |
| 8. 73-year old man | Two years PTA underwent resection of grade 2 bladder urothelial carcinoma | Severe constipation | Sigmoidoscopy: Friable, erythematous, and thickened distal rectal wall, with nearly obstructed lumen. EUS: Hypoechoic, symmetric, circumferential wall thickening, with loss of deep wall layers, and pseudopodia-like extensions into perirectal tissues. No evident direct tumor extension from bladder | Rectum: Poorly differentiated urothelial carcinoma | Total pelvic exenteration and chemotherapy (regimen not specified) | NR | Yusuf et al[ |
| 9. 67-year-old man | Eighteen months PTA underwent transurethral excisional biopsy of bladder cancer. Ten months PTA underwent partial cystectomy, chemotherapy with gemcitabine, and RT. 1 mo PTA, nephrostomy tubes inserted for bilateral hydronephrosis | Massive rectal bleeding and altered mental status for one day. HR = 106 beats/min, BP = 65 mmHg/palpable. Rectal exam: Rectal mass and large amount of bright red blood and clots. Hemoglobin = 8.0 g/dL | Selective angiography of celiac trunk, superior mesenteric artery and inferior mesenteric artery: No bleeding source identified. Colonoscopy: Large amount of bright red blood in colon. Emergency laparotomy: Indurated, fixed, mass involving cecum, right lower retroperitoneum, and right pelvic side wall. Dilated colon. Active bleeding from fistula between iliac artery and cecum | Cecum: Urothelial carcinoma | Resection of cecum and terminal ileum, ligation of right external iliac artery, end-ileostomy | Alive at 6 mo | Chin et al[ |
BP: Blood pressure; CT: Computed tomography; ERCP: Endoscopic retrograde cholangiopancreatography; GI: Gastrointestinal; HR: Heart rate; M-VAC: Methotrexate, vinblastine, Adriamycin; NR: Not reported; PET: Positive electron tomography; PTA: Prior to admission; RFA: Radiofrequency ablation; RT: Radiation therapy; TURBT: Transurethral resection of bladder tumor; EUS: Endoscopic ultrasound; NA: Not available.
Metastases of urothelial bladder carcinoma to the esophagus, stomach, and small intestine
| 1. 55-year-old man | 1 mo PTA underwent total cystoprostatectomy, bilateral ilio-obturator lymphadenectomy, and bladder reconstruction for bladder urothelial carcinoma pT3-GIII, N0 | Hematemesis 8 d after surgery | Chest and abdominopelvic CT: Esophageal mass. EGD: 2-cm-wide mass in proximal esophagus. EUS: No lymphadenopathy | Esophagus: Urothelial carcinoma infiltrating submucosa | Chemotherapy with M-VAC, and RT of metastasis | Developed radiation pericarditis but recovered. Alive at 2 yr | Jung et al[ |
| 2. 66-year-old man | No prior oncologic history | Dysphagia, anorexia, weight loss, headaches, and lightheadedness for 6 wk. Palpable, tender, 2 cm mass on left neck | Neck and thoracic CT: 3 cm × 2 cm soft tissue mass with dilation and thickening of proximal esophagus. EGD: Focal stricture at 25 cm from incisors with a 2 cm × 1 cm ulcer with irregular margins | Esophagus: Poorly differentiated urothelial carcinoma | None | Died 10 d after discharge from hospital | Dy et al[ |
| 3. 80-year-old man | Four years PTA underwent RT and chemotherapy (after declining radical cystectomy) for bladder urothelial carcinoma. Three years PTA underwent lung lobe wedge resection for solitary lung metastasis. 1 mo PTA had a normal EGD and colonoscopy in evaluation of anemia | Malaise, dizziness, dyspnea, melena. Rectal exam: Positive occult blood in stool. Hemoglobin = 5.4 g/dL | Small bowel enteroscopy: 3 cm, ulcerated, infiltrating tumor in distal duodenum. Tumor has an adherent, friable, clot | Duodenum: High-grade urothelial carcinoma | Duodenectomy and duodenomy jejunostomy | PET scan 2 mo later: Metastases to liver and lungs. Patient expired soon thereafter from cardiac arrhythmia | Girotra et al[ |
| 4. 62-year-old man | Two years PTA underwent partial cystectomy with lymph node dissection and adjuvant chemotherapy for stage IIIb bladder urothelial carcinoma | Hematemesis, hemoglobin = 7.0 g/dL | EGD: Large bleeding mass in descending duodenum. Treated with proton pump inhibitor therapy. Repeat EGD 4 d later: large partly obstructing, 7-cm-long mass in descending duodenum | Duodenum: Poorly differentiated urothelial carcinoma | Palliative radiation | Died 6 wk later | Chan et al[ |
| 5. 74-year-old man | Four years PTA underwent exploratory laparotomy which demonstrated nodal metastasis. Completed preoperative chemotherapy, but declined surgical resection | Abdominal pain, bloating, distention, nausea, and vomiting | Serial pelvic CT (to monitor cancer progression): Stable bladder wall thickening Small bowel barium contrast radiography: Narrowing of third portion of duodenum Gastroscopy: Fluid-filled, dilated, stomach without obstruction. EGD: Luminal narrowing with overlying normal mucosa in third portion of duodenum. EUS: Circumferential wall thickening | Duodenum: urothelial carcinoma | Enteral stent and palliative chemotherapy | Died 9 mo later | Yusuf et al[ |
| 6. 42-year-old woman | No prior oncologic history | Nausea, vomiting, abdominal discomfort, and 6-kg weight loss for 2 mo | Barium meal: Abrupt stricture at junction between second and third portion of duodenum. Abdominopelvic CT: Infiltrative soft tissue mass around duodenum, calcified bladder wall. No pelvic lymphadenopathy. EGD: Gastric outlet obstruction with distorted and erythematous duodenum without ulceration, or mucosal tumor | Duodenum: Micropapillary variant of poorly differentiated urothelial carcinoma | Duodenal stent and RT to periduode-nal lesion. Administered palliative gemcitabine and carboplatin | Died 15 mo after diagnosis | Hawtin et al[ |
| 7. 87-year-old man | Sixteen months PTA underwent TURBT for grade 3, pT2bN0M0, bladder urothelial carcinoma | Ileus | Abdominopelvic CT: Pneumoperitoneum due to GI perforation Laparotomy: Elastic hard tumor at site of ileal perforation | Ileum: Metastatic urothelial carcinoma | Partial resection of ileum | NA | Hoshi et al[ |
| 8. 53-year-old man | No prior oncologic history | Gross hematuria | Abdominopelvic CT: Bladder tumor invading prostate. Cystoscopy: Non-papillary, broad based, tumor in right wall of bladder | Ileum and prostate: Urothelial carcinoma pT4aN1M0 | Total cystec--tomy and creation of ileal conduit. Neoadjuvant chemotherapy | NA | Hoshi et al[ |
| 9. 56-year-old man | Fifty-nine months PTA underwent TURBT for bladder urothelial carcinoma | Abdominal pain and GI perforation | NA | Small intestine, lymph nodes, lung, and liver: Urothelial carcinoma | NA | NA | Hoshi et al[ |
| 10. 63-year-old woman | Seven months PTA underwent total cystectomy for pT3b bladder urothelial carcinoma | Abdominal pain | NR | Small intestine: Urothelial carcinoma | NR | NR | Hoshi et al[ |
| 11. 46-year-old man | Thirty-eight months PTA underwent RT and chemotherapy for pT3b bladder urothelial carcinoma | Ileus | NR | Small intestine: Urothelial carcinoma | NR | NR | Hoshi et al[ |
| 12. 71-year-old man | Thirty-six months PTA underwent total cystectomy for bladder urothelial carcinoma | Melena and anemia | NR | Small intestine: Urothelial carcinoma | NR | NR | Hoshi et al[ |
| 13. 55-year-old man | Seven years PTA underwent total cystectomy, pelvic lymphadenectomy, and neobladder reconstruction. Underwent two cycles of adjuvant chemotherapy for pT3apN0 G2 bladder urothelial carcinoma | Massive melena, HR = 120 beats/min, BP = 72/36 mmHg. Hemoglobin = 7.9 g/dL | Abdominopelvic CT: Right hydronephrosis from external iliac lymph node metastasis invading ileum. Angiography: Right external iliac artery successfully embolized using microcoils and n-butyl cyanoacrylate. Then developed ischemic colitis, treated with iliac artery bypass grafting, and right common and internal iliac artery embolization | Ileum: NR | Three cycles of unspecified chemotherapy | Died 4 mo after embolization | Honda et al[ |
BC: Bladder cancer; BP: Blood pressure; CT: Computed tomography; EGD: Esophagogastroduodenoscopy; GI: Gastrointestinal, HR: Heart rate; M-VAC: Methotrexate, vinblastine, Adriamycin; NR: Not reported; PTA: Prior to admission; RT: Radiation therapy; TURBT: Transurethral resection of bladder tumor; EUS: Endoscopic ultrasound.
Figure 1Abdominopelvic computed tomography angiography demonstrating thickened bladder wall (red arrowhead), with adjacent prostate margin (dashed arrow). Air-filled cavity within the prostate gland (white arrowhead), is consistent with the known bladder urothelial carcinoma penetrating, via the prostate, into the rectum (horizontal solid arrows). The colonoscopic findings (Figure 2) strongly support this mechanism of cancer spread.
Figure 2Colonoscopy reveals, just above the anorectal margin (line between pale skin and red mucosa), a multinodular, friable, 2.5-cm-wide, hemorrhagic, mass that replaces the normal prostate and overlying rectum (A, B). Tissue surrounding the lesion appears to be normal. Biopsy of this mass revealed bladder urothelial carcinoma. The finding of bladder urothelial carcinoma in the normal location of the prostate and overlying rectum, just inferior to the bladder cancer, is consistent with direct extension of bladder urothelial carcinoma into the immediately adjacent prostate and its overlying rectal mucosa. This cancer location is highly consistent with the abdominopelvic computed tomography findings (Figure 1).
Figure 3Histologic examination and immunohistochemical analysis. A: Low power photomicrograph shows segments of detached poorly differentiated cancer (arrows), amidst segments of normal rectal mucosa (arrowhead). Right inset shows high power photomicrograph of polygonal tumor cells (HE stain) that have a histologic appearance characteristic for urothelial carcinoma. Immunohistochemistry confirmed the urothelial histology of the cancer (Figure 3B and C); B: Left: Immunohistochemistry for cytokeratin-20 demonstrates positive staining of tumor cytoplasm. Right: Immunohistochemistry for GATA-3 demonstrates positive staining of tumor cell nuclei. This immunohistochemical profile indicates that the rectal mass is of urothelial origin; C: Immunohistochemistry for CDX-2 shows negative staining of tumor cell nuclei, indicating that this tumor is not colonic adenocarcinoma. Right inset is a control of normal colonic glands set on the same slide which demonstrates positive nuclear staining for CDX-2.