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Squamous metaplasia of the rectum after argon plasma coagulation
Brief Reports
S Lee, MD, R Haggitt, M Kimmey
Squamous metaplasia of the rectum after argon plasma coagulation Scott D. Lee, MD, Rodger C. Haggitt, MD, Michael B. Kimmey, MD
Squamous metaplasia of the rectum occurs only rarely and has been reported in association with chronic inflammation and carcinoma and in one patient who had no other associated disease.1-5 This is a report of the development of squamous metaplasia of the rectum after argon plasma coagulation of a villous adenoma. CASE REPORT A 64-year-old man was referred for endoscopic therapy of a recurrent rectal villous adenoma. Previously, he had undergone three trans-anal excisions over 12 years in an attempt to remove the lesion. All of the resected specimens revealed benign villous adenoma without evidence of squamous metaplasia. Despite this, he continued to From the University of Washington, Departments of Medicine and Pathology, Seattle, Washington. Reprint requests: Michael B. Kimmey, MD, University of Washington Medical Center, Division of Gastroenterology, 1959 NE Pacific St., Box 356424, Seattle, WA 98195; fax 206-685-8684. Copyright © 2000 by the American Society for Gastrointestinal Endoscopy 0016-5107/2000/$12.00 + 0 37/54/109719 doi:10.1067/mge.2000.109719 VOLUME 52, NO. 5, 2000
have recurrence of the lesion and symptoms of rectal mucous discharge. On initial examination, inspection of the anus was normal. A digital rectal examination did not reveal a discrete mass, but a soft, velvety lesion was palpated just inside the anal canal. On sigmoidoscopic evaluation, a 4 cm diameter villiform carpet-like lesion involving one third of the circumference of the distal rectum abutted the dentate line (Fig. 1). The argon plasma coagulator was used to ablate all visible polypoid tissue using a power of 60 watts. Small areas of remaining polypoid tissue in the distal rectum were also treated using argon plasma coagulation with the same power, 1 and 3 months later. The patient’s symptom of mucous discharge resolved. Nine months after the first argon plasma coagulation, the patient returned for routine follow-up surveillance. Grayish colored mucosa was observed in the areas of previous argon plasma coagulation, in continuity with the squamous epithelium of the anal canal (Fig. 2). A small amount of polypoid tissue remained in the distal rectum, along with evidence of scarring in previously coagulated areas. The residual polypoid tissue was again treated with the argon plasma coagulator at a power of 60 watts. Four months later at the fifth session, no residual adenoma was detected. A biopsy of the smooth gray mucosal lining of the distal rectum was obtained. Histologic evaluation revealed normal squamous mucosa with no evidence of dysplasia or malignancy and no underlying columnar epithelium (Fig. 3). Sixteen months after the squamous metaplasia was first noted, the patient was asymptomatic with daily formed bowel movements without visible mucus or bleeding. GASTROINTESTINAL ENDOSCOPY
683
S Lee, MD, R Haggitt, M Kimmey
Figure 1. Endoscopic image of rectal villous adenoma before argon plasma coagulation.
Figure 2. Endoscopic image of squamous metaplasia of the rectum in the region of argon plasma coagulation of the villous adenoma.
DISCUSSION Squamous metaplasia of the rectum occurs rarely and is of unknown significance. The origin of the squamous cells is unknown. One hypothesis is that they arise from a pluripotent stem cell in the rectal mucosa that is stimulated to differentiate into squamous epithelium.6 Another postulate is that the cells originate from ingrowth of adjacent squamous epithelium. In the case of the rectum, this may be from ectopic nests of squamous epithelium in the rectal mucosa that proliferate when stimulated, or from proximal extension from the squamous lining of the anal canal. Squamous replacement of columnar epithelium in the esophagus after laser ablation or photodynamic therapy of Barrett’s mucosa has been well documented.7-9 To our knowledge, this case is the 684
GASTROINTESTINAL ENDOSCOPY
Brief Reports
Figure 3. Photomicrograph of an endoscopic biopsy from the area of squamous metaplasia showing squamous epithelium with mild hyperplasia (H&E, ×80).
only one reported in which squamous metaplasia of the rectum developed after treatment with argon plasma coagulation. Although there have been numerous reports of successful Nd/YAG laser treatment of villous adenomas, there are no reports of evidence of squamous metaplasia on follow-up endoscopy.10-12 The clinical significance of this phenomenon in the rectum is unclear. Squamous metaplasia has been associated with both inflammation and squamous carcinoma, but there is no clear evidence of a causal relationship.1,2,5 Squamous metaplasia has also been found within rectal adenomas.13,14 In previous reports, patients with squamous metaplasia have experienced acrid discharge, intermittent hematochezia, constipation, and itching. Local excision of the squamous epithelium has been advocated for these patients.6 In the present case the patient has been asymptomatic for 33 months and biopsies have not shown any evidence of dysplasia. This patient will be followed up with surveillance sigmoidoscopy, and further biopsies will be taken of the squamous metaplasia, to ensure that areas of dysplasia were not missed due to sampling error and that no residual adenomatous tissue persists beneath the squamous mucosa. However, unless clinical symptoms or evidence of dysplasia develop, further intervention is not warranted. REFERENCES 1. David VC. Leukoplakia of the rectum. Arch Pathol 1938;26: 151-4. 2. Dukes CE. The significance of the unusual in the pathology of intestinal tumours. Ann Royal Coll Surg Engl 1949;4:90-103. 3. Cabrera A, Pickren JW. Squamous metaplasia and squamouscell carcinoma of the rectosigmoid. Dis Colon Rectum 1967;10:288-97. VOLUME 52, NO. 5, 2000
Brief Reports
4. Woods WGA. Squamous cell carcinoma of the rectum arising in an area of squamous metaplasia. Eur J Surg Oncol 1987;13:455-8. 5. Zirkin RM, McCord DL. Squamous cell carcinoma of the rectum: report of a case complicating chronic ulcerative colitis. Dis Colon Rectum 1963;6:370-3. 6. Chen FCS, Fink RLW, Machet D. Squamous metaplasia of the rectum: a surgical curiosity. Eur J Surg 1996;162:155-6. 7. Biddlestone LR, Barham CP, Wilkinson SP, Barr H, Shepherd NA. The histopathology of treated Barrett’s esophagus: squamous reepitheliazation after acid suppression and laser and photodynamic therapy. Am J Surg Pathol 1998;22:239-45. 8. Berenson MM, Johnson T, Markowitz NR, Buchi KN, Samowitz WS. Restoration of squamous mucosa after ablation of Barrett’s oesophageal epithelium. Gastroenterology 1993;104:1686-91. 9. Byrne J, Armstrong G, Attwood S. Restoration of the normal
VOLUME 52, NO. 5, 2000
10.
11.
12.
13. 14.
squamous lining in Barrett’s esophagus by argon beam plasma coagulation. Am J Gastroenterol 1998;93:1810-15. Auber A, Meduri B, Fritsch J, Aime F, Baglin A, Barbagelata M. Endoscopic treatment by snare electrocoagulation prior to Nd:YAG laser photocoagulation in 85 voluminous colorectal villous adenomas. Dis Colon Rectum 1991;34:372-7. Conio M, Caroli-bosc F, Filiberti R, Dumas R, Rouquier P, Demarquay J, et al. Endoscopic Nd:YAG laser therapy for villous adenomas of the right colon. Gastrointest Endosc 1999; 49:504-8. Hyser MJ, Gau FC. Endoscopic Nd:YAG laser therapy for villous adenomas of the colon and rectum. Am Surg 1996;62: 577-80. Almagro UA, Pintar K, Zellmer RB. Squamous metaplasia in colorectal polyps. Cancer 1984;53:2679-82. Chen KTK. Colonic adenomatous polyp with focal squamous metaplasia. Hum Pathol 1981;12:848-9.
GASTROINTESTINAL ENDOSCOPY
685
S Lee, MD, R Haggitt, M Kimmey
Squamous metaplasia of the rectum after argon plasma coagulation Scott D. Lee, MD, Rodger C. Haggitt, MD, Michael B. Kimmey, MD
Squamous metaplasia of the rectum occurs only rarely and has been reported in association with chronic inflammation and carcinoma and in one patient who had no other associated disease.1-5 This is a report of the development of squamous metaplasia of the rectum after argon plasma coagulation of a villous adenoma. CASE REPORT A 64-year-old man was referred for endoscopic therapy of a recurrent rectal villous adenoma. Previously, he had undergone three trans-anal excisions over 12 years in an attempt to remove the lesion. All of the resected specimens revealed benign villous adenoma without evidence of squamous metaplasia. Despite this, he continued to From the University of Washington, Departments of Medicine and Pathology, Seattle, Washington. Reprint requests: Michael B. Kimmey, MD, University of Washington Medical Center, Division of Gastroenterology, 1959 NE Pacific St., Box 356424, Seattle, WA 98195; fax 206-685-8684. Copyright © 2000 by the American Society for Gastrointestinal Endoscopy 0016-5107/2000/$12.00 + 0 37/54/109719 doi:10.1067/mge.2000.109719 VOLUME 52, NO. 5, 2000
have recurrence of the lesion and symptoms of rectal mucous discharge. On initial examination, inspection of the anus was normal. A digital rectal examination did not reveal a discrete mass, but a soft, velvety lesion was palpated just inside the anal canal. On sigmoidoscopic evaluation, a 4 cm diameter villiform carpet-like lesion involving one third of the circumference of the distal rectum abutted the dentate line (Fig. 1). The argon plasma coagulator was used to ablate all visible polypoid tissue using a power of 60 watts. Small areas of remaining polypoid tissue in the distal rectum were also treated using argon plasma coagulation with the same power, 1 and 3 months later. The patient’s symptom of mucous discharge resolved. Nine months after the first argon plasma coagulation, the patient returned for routine follow-up surveillance. Grayish colored mucosa was observed in the areas of previous argon plasma coagulation, in continuity with the squamous epithelium of the anal canal (Fig. 2). A small amount of polypoid tissue remained in the distal rectum, along with evidence of scarring in previously coagulated areas. The residual polypoid tissue was again treated with the argon plasma coagulator at a power of 60 watts. Four months later at the fifth session, no residual adenoma was detected. A biopsy of the smooth gray mucosal lining of the distal rectum was obtained. Histologic evaluation revealed normal squamous mucosa with no evidence of dysplasia or malignancy and no underlying columnar epithelium (Fig. 3). Sixteen months after the squamous metaplasia was first noted, the patient was asymptomatic with daily formed bowel movements without visible mucus or bleeding. GASTROINTESTINAL ENDOSCOPY
683
S Lee, MD, R Haggitt, M Kimmey
Figure 1. Endoscopic image of rectal villous adenoma before argon plasma coagulation.
Figure 2. Endoscopic image of squamous metaplasia of the rectum in the region of argon plasma coagulation of the villous adenoma.
DISCUSSION Squamous metaplasia of the rectum occurs rarely and is of unknown significance. The origin of the squamous cells is unknown. One hypothesis is that they arise from a pluripotent stem cell in the rectal mucosa that is stimulated to differentiate into squamous epithelium.6 Another postulate is that the cells originate from ingrowth of adjacent squamous epithelium. In the case of the rectum, this may be from ectopic nests of squamous epithelium in the rectal mucosa that proliferate when stimulated, or from proximal extension from the squamous lining of the anal canal. Squamous replacement of columnar epithelium in the esophagus after laser ablation or photodynamic therapy of Barrett’s mucosa has been well documented.7-9 To our knowledge, this case is the 684
GASTROINTESTINAL ENDOSCOPY
Brief Reports
Figure 3. Photomicrograph of an endoscopic biopsy from the area of squamous metaplasia showing squamous epithelium with mild hyperplasia (H&E, ×80).
only one reported in which squamous metaplasia of the rectum developed after treatment with argon plasma coagulation. Although there have been numerous reports of successful Nd/YAG laser treatment of villous adenomas, there are no reports of evidence of squamous metaplasia on follow-up endoscopy.10-12 The clinical significance of this phenomenon in the rectum is unclear. Squamous metaplasia has been associated with both inflammation and squamous carcinoma, but there is no clear evidence of a causal relationship.1,2,5 Squamous metaplasia has also been found within rectal adenomas.13,14 In previous reports, patients with squamous metaplasia have experienced acrid discharge, intermittent hematochezia, constipation, and itching. Local excision of the squamous epithelium has been advocated for these patients.6 In the present case the patient has been asymptomatic for 33 months and biopsies have not shown any evidence of dysplasia. This patient will be followed up with surveillance sigmoidoscopy, and further biopsies will be taken of the squamous metaplasia, to ensure that areas of dysplasia were not missed due to sampling error and that no residual adenomatous tissue persists beneath the squamous mucosa. However, unless clinical symptoms or evidence of dysplasia develop, further intervention is not warranted. REFERENCES 1. David VC. Leukoplakia of the rectum. Arch Pathol 1938;26: 151-4. 2. Dukes CE. The significance of the unusual in the pathology of intestinal tumours. Ann Royal Coll Surg Engl 1949;4:90-103. 3. Cabrera A, Pickren JW. Squamous metaplasia and squamouscell carcinoma of the rectosigmoid. Dis Colon Rectum 1967;10:288-97. VOLUME 52, NO. 5, 2000
Brief Reports
4. Woods WGA. Squamous cell carcinoma of the rectum arising in an area of squamous metaplasia. Eur J Surg Oncol 1987;13:455-8. 5. Zirkin RM, McCord DL. Squamous cell carcinoma of the rectum: report of a case complicating chronic ulcerative colitis. Dis Colon Rectum 1963;6:370-3. 6. Chen FCS, Fink RLW, Machet D. Squamous metaplasia of the rectum: a surgical curiosity. Eur J Surg 1996;162:155-6. 7. Biddlestone LR, Barham CP, Wilkinson SP, Barr H, Shepherd NA. The histopathology of treated Barrett’s esophagus: squamous reepitheliazation after acid suppression and laser and photodynamic therapy. Am J Surg Pathol 1998;22:239-45. 8. Berenson MM, Johnson T, Markowitz NR, Buchi KN, Samowitz WS. Restoration of squamous mucosa after ablation of Barrett’s oesophageal epithelium. Gastroenterology 1993;104:1686-91. 9. Byrne J, Armstrong G, Attwood S. Restoration of the normal
VOLUME 52, NO. 5, 2000
10.
11.
12.
13. 14.
squamous lining in Barrett’s esophagus by argon beam plasma coagulation. Am J Gastroenterol 1998;93:1810-15. Auber A, Meduri B, Fritsch J, Aime F, Baglin A, Barbagelata M. Endoscopic treatment by snare electrocoagulation prior to Nd:YAG laser photocoagulation in 85 voluminous colorectal villous adenomas. Dis Colon Rectum 1991;34:372-7. Conio M, Caroli-bosc F, Filiberti R, Dumas R, Rouquier P, Demarquay J, et al. Endoscopic Nd:YAG laser therapy for villous adenomas of the right colon. Gastrointest Endosc 1999; 49:504-8. Hyser MJ, Gau FC. Endoscopic Nd:YAG laser therapy for villous adenomas of the colon and rectum. Am Surg 1996;62: 577-80. Almagro UA, Pintar K, Zellmer RB. Squamous metaplasia in colorectal polyps. Cancer 1984;53:2679-82. Chen KTK. Colonic adenomatous polyp with focal squamous metaplasia. Hum Pathol 1981;12:848-9.
GASTROINTESTINAL ENDOSCOPY
685