SYNCHRONOUS ANAL MELANOMA AND COLON ADENOCARCINOMA: CASE REPORT AND REVIEW OF DIAGNOSIS AND MANAGEMENT

Eduardo Henrique PIROLLA Felipe Piccarone Gonçalves RIBEIRO Fernanda Junqueira Cesar PIROLA Camila COSMO Melany Di BIASI About the authors

HEADINGS :
Melanoma; Adenocarcinoma; Diagnosis

INTRODUCTION

Malignant anal melanoma is a rare disorder, corresponding to 0.05-1.0% of all anorectal tumors, and 0.4-1.6% of all other melanomas77. Jorge E, Harvey HA, Simmonds MA, Lipton A, Joehl RJ. Symptomatic malignant melanoma of the gastrointestinal tract. Operative treatment and survival. Ann Surg. 1984 Mar;199(3):328-31.,88. Kantarovsky A, Kaufman Z, Zager M, Lew S, Dinbar A. Anorectal region malignant melanoma. J Surg Oncol. 1988 Jun;38(2):77-9.,99. Knysh VI, Timofeev IuM, Serebriakova ES. [Treatment of melanomas of the anorectal region]. Vopr Onkol. 1987;33(3):74-8.. Its rarity can be confirmed by the fact that for every anal melanoma, there are eight squamous cell carcinomas and 250 anal adenocarcinomas88. Kantarovsky A, Kaufman Z, Zager M, Lew S, Dinbar A. Anorectal region malignant melanoma. J Surg Oncol. 1988 Jun;38(2):77-9.,99. Knysh VI, Timofeev IuM, Serebriakova ES. [Treatment of melanomas of the anorectal region]. Vopr Onkol. 1987;33(3):74-8..

The article´s aim is to present a case of a malignant anal melanoma coexisting with colon adenocarcinoma, in addition to a discussion on how to speed up the diagnosis with simple routine measures, and report an objective treatment.

CASE REPORT

A 57-year-old patient was admitted with weakness, pale skin and a lump in the inguinal region. According to his medical history, one year prior to admittance the patient was treated for anemia. At the time, he presented positive fecal occult blood test. Endoscopy and contrast exams were normal and no weight loss or changes in bowel movements were noticed.

In the six months prior to admittance, the patient felt sporadic pain in the anal canal that ceased with the use of NSAID suppositories. After 30 days, he sought medical attendance and underwent proctosigmoidoscopy and colonoscopy, along with biopsy of lesions in the anal canal and cecum. The patient was then diagnosed with poorly differentiated carcinoma of the canal and well differentiated tubular adenocarcinoma of the cecum. At the time, a lump began forming in the root of the thigh, just below the inguinal fold.

The patient was refered to Sírio-Libanês Hospital in São Paulo, Brazil, for surgical treatment of the colon lesion and clinical treatment of the anal canal lesion (Figure 1), as he refused to operate the anal lesion. Abdominal ultrasonography and thorax tomography did not reveal any findings. Surgery was then performed with right ileocecal colectomy, intra-operatory biopsy of lesion in the anal canal and of the right inguinal lymph node.

FIGURE 1
Circunferencial anal lesion in all anorectal canal

Anatomopathological findings of the anal canal revealed an amelanotic malignant melanoma with extensive infiltration and presence of ulcerations and necrosis (Figure 2); right inguinal lesion was a metastatic amelanotic malignant melanoma.

FIGURE 2
A) Amelanotic epithelioid type (H&E) and B) epithelioid/lymphoma-like (Study S-100 protein)

Findings on the colon lesion revealed a segment of the left colon had histological stage II invasive tubular adenocarcinoma, a presence of 20% of mucous membrane, diffuse and extensive infiltration of the colon wall up to the peripheral adipose tissue, ulcerous lesion with irregular areas and necrosis, discreet fibrosis and inflammatory infiltration, and absence of vascular or peri-neural invasion. The anatomopathological examination of surgical borders revealed absence of neoplasm. Assessment of mesocolic lymph nodes exhibited reactive lymphoid hyperplasia with no metastasis (0/13).

The patient refused surgical treatment on the anal canal and neglected follow-up. After two months, he returned with exophytic lesion and bleeding, along with significant loss of weight and pain. In the 30 days before hospitalization he presented important anal bleeding with spontaneous remission. In the 6th day prior to hospitalization, there was a new episode of bleeding, which led to hospitalization. A new abdominal tomography showed multiple adenomegalies in the paraaortic, paracaval, inguinal, and bilateral perirectal lymph nodes. It also revealed a heterogenic mass with imprecise limits, compatible with ganglion conglomerates of mesenteric origin, next to the hepatic angle of the colon; presence of a soft tissue mass in the anal canal, extending to the ischiorectal fossa towards the perineal border, predominantly on the left, with no dividing plane with the elevator muscle of the anus. Due to the bleeding and ulceration, a colonostomy was performed and local radiotherapy began. After the third session of 300 rads in each there was significant improvement of the bleeding, which stopped after the fourth session. There was clinical improvement and the patient is currently undergoing monitoring.

DISCUSSION

Malignant anorectal melanoma was first described by Moore in 185711. Campos FGCM, Habr-Gama A, Silva JH, Ibrahim RE, Tudor R, Pinotti HW. Malignant melanoma of the anorectal region: report of a case and review of the literature. ABCD. Arq Bras Cirg Dig, 1989;4(4), 102-7.. The origin of the tumor appears to be ectodermic, although the presence of melanocytes in the colorectal, above the squamous and transitional regions of the anal canal, proves that the tumor can originate above just as bellow the pectinate line11. Campos FGCM, Habr-Gama A, Silva JH, Ibrahim RE, Tudor R, Pinotti HW. Malignant melanoma of the anorectal region: report of a case and review of the literature. ABCD. Arq Bras Cirg Dig, 1989;4(4), 102-7.,22. Clemmensen OJ, Fenger C. Melanocytes in the anal canal epithelium.Histopathology. 1991 Mar;18(3):237-41.,1111. Singh W, Madaan TR. Malignant melanoma of the anal canal. Am J Proctol. 1976 Feb;27(1):49-55.. Some authors argue that, in almost all cases, the tumor originates in the pectinate line and grows in the submucous space, scrolling through the tissue to emerge on the mucosa at a higher point, thus simulating a primary rectal tumor22. Clemmensen OJ, Fenger C. Melanocytes in the anal canal epithelium.Histopathology. 1991 Mar;18(3):237-41.,66. Goldman S, Glimelius B, Påhlman L. Anorectal malignant melanoma in Sweden. Report of 49 patients. Dis Colon Rectum. 1990 Oct;33(10):874-7..

The prognosis is poor since the survival rate is low55. García Montes JM, Jiménez Sáenz M, Hernández Peña M, Herrerías Gutiérrez JM.[Anorectal melanoma]. Rev Esp Enferm Apar Dig. 1989 Aug;76(2):173-5.,88. Kantarovsky A, Kaufman Z, Zager M, Lew S, Dinbar A. Anorectal region malignant melanoma. J Surg Oncol. 1988 Jun;38(2):77-9.,1313. Wong JH, Cagle LA, Storm FK, Morton DL. Natural history of surgically treated mucosal melanoma. Am J Surg. 1987 Jul;154(1):54-7.. Some authors relate this to a late diagnosis in most cases11. Campos FGCM, Habr-Gama A, Silva JH, Ibrahim RE, Tudor R, Pinotti HW. Malignant melanoma of the anorectal region: report of a case and review of the literature. ABCD. Arq Bras Cirg Dig, 1989;4(4), 102-7.,33. Dhaliwal VS, et al. Malignant melanoma of anorectal; J. Indian M.A., 1987, 85(11), 341-3.,1212. Slingluff CL Jr, Vollmer RT, Seigler HF. Anorectal melanoma: clinical characteristics and results of surgical management in twenty-four patients. Surgery. 1990 Jan;107(1):1-9..

The early signs and symptoms are similar to other colorectal diseases, being most frequent anal bleeding, local pain, changes in bowel habits, and in many times, the growth of lumps in the region11. Campos FGCM, Habr-Gama A, Silva JH, Ibrahim RE, Tudor R, Pinotti HW. Malignant melanoma of the anorectal region: report of a case and review of the literature. ABCD. Arq Bras Cirg Dig, 1989;4(4), 102-7.,33. Dhaliwal VS, et al. Malignant melanoma of anorectal; J. Indian M.A., 1987, 85(11), 341-3.,88. Kantarovsky A, Kaufman Z, Zager M, Lew S, Dinbar A. Anorectal region malignant melanoma. J Surg Oncol. 1988 Jun;38(2):77-9.,1212. Slingluff CL Jr, Vollmer RT, Seigler HF. Anorectal melanoma: clinical characteristics and results of surgical management in twenty-four patients. Surgery. 1990 Jan;107(1):1-9.. The difficulty in diagnosing is brought by the similarities of the symptoms with hemorrhoidal disease or anal fissure, as well as the fact that in 16-41% of lesions lack pigmentation11. Campos FGCM, Habr-Gama A, Silva JH, Ibrahim RE, Tudor R, Pinotti HW. Malignant melanoma of the anorectal region: report of a case and review of the literature. ABCD. Arq Bras Cirg Dig, 1989;4(4), 102-7.,88. Kantarovsky A, Kaufman Z, Zager M, Lew S, Dinbar A. Anorectal region malignant melanoma. J Surg Oncol. 1988 Jun;38(2):77-9.,1212. Slingluff CL Jr, Vollmer RT, Seigler HF. Anorectal melanoma: clinical characteristics and results of surgical management in twenty-four patients. Surgery. 1990 Jan;107(1):1-9..

The incidence is greater in women11. Campos FGCM, Habr-Gama A, Silva JH, Ibrahim RE, Tudor R, Pinotti HW. Malignant melanoma of the anorectal region: report of a case and review of the literature. ABCD. Arq Bras Cirg Dig, 1989;4(4), 102-7.,88. Kantarovsky A, Kaufman Z, Zager M, Lew S, Dinbar A. Anorectal region malignant melanoma. J Surg Oncol. 1988 Jun;38(2):77-9.,1212. Slingluff CL Jr, Vollmer RT, Seigler HF. Anorectal melanoma: clinical characteristics and results of surgical management in twenty-four patients. Surgery. 1990 Jan;107(1):1-9.. The average age group consists of patients in their sixties and seventies55. García Montes JM, Jiménez Sáenz M, Hernández Peña M, Herrerías Gutiérrez JM.[Anorectal melanoma]. Rev Esp Enferm Apar Dig. 1989 Aug;76(2):173-5.,66. Goldman S, Glimelius B, Påhlman L. Anorectal malignant melanoma in Sweden. Report of 49 patients. Dis Colon Rectum. 1990 Oct;33(10):874-7.,1212. Slingluff CL Jr, Vollmer RT, Seigler HF. Anorectal melanoma: clinical characteristics and results of surgical management in twenty-four patients. Surgery. 1990 Jan;107(1):1-9..

Resection is the treatment of choice among the authors depending on the size of the lesion. The level of infiltration and presence of metastases are some of the factors considered when choosing the extension of resection11. Campos FGCM, Habr-Gama A, Silva JH, Ibrahim RE, Tudor R, Pinotti HW. Malignant melanoma of the anorectal region: report of a case and review of the literature. ABCD. Arq Bras Cirg Dig, 1989;4(4), 102-7.,99. Knysh VI, Timofeev IuM, Serebriakova ES. [Treatment of melanomas of the anorectal region]. Vopr Onkol. 1987;33(3):74-8.. Previous or adjuvant postoperative radiotherapy and chemotherapy is very debatable.

Many authors believe that the origin of these tumors is in the dentate line, where melanocytes have been detected11. Campos FGCM, Habr-Gama A, Silva JH, Ibrahim RE, Tudor R, Pinotti HW. Malignant melanoma of the anorectal region: report of a case and review of the literature. ABCD. Arq Bras Cirg Dig, 1989;4(4), 102-7.,22. Clemmensen OJ, Fenger C. Melanocytes in the anal canal epithelium.Histopathology. 1991 Mar;18(3):237-41.,88. Kantarovsky A, Kaufman Z, Zager M, Lew S, Dinbar A. Anorectal region malignant melanoma. J Surg Oncol. 1988 Jun;38(2):77-9.. Iron ions have been used for staining, currently; the Masson-Fontana technique is used to show melanocytes above the dentate line22. Clemmensen OJ, Fenger C. Melanocytes in the anal canal epithelium.Histopathology. 1991 Mar;18(3):237-41.,55. García Montes JM, Jiménez Sáenz M, Hernández Peña M, Herrerías Gutiérrez JM.[Anorectal melanoma]. Rev Esp Enferm Apar Dig. 1989 Aug;76(2):173-5.,88. Kantarovsky A, Kaufman Z, Zager M, Lew S, Dinbar A. Anorectal region malignant melanoma. J Surg Oncol. 1988 Jun;38(2):77-9.. The most up-to-date techniques use immunohystochemical reactions such as S-100 protein (antibodies S-100), which has greater sensibility, but less specificity. Monoclonal antibodies are also used as a detection method, such as HMB-45 (monoclonal Enzo)22. Clemmensen OJ, Fenger C. Melanocytes in the anal canal epithelium.Histopathology. 1991 Mar;18(3):237-41..

The Breslow classification is best used to classify the depth of the tumor11. Campos FGCM, Habr-Gama A, Silva JH, Ibrahim RE, Tudor R, Pinotti HW. Malignant melanoma of the anorectal region: report of a case and review of the literature. ABCD. Arq Bras Cirg Dig, 1989;4(4), 102-7.,88. Kantarovsky A, Kaufman Z, Zager M, Lew S, Dinbar A. Anorectal region malignant melanoma. J Surg Oncol. 1988 Jun;38(2):77-9.. This method is preferred to the Clark classification, regarding the lack of papillary dermis in the region11. Campos FGCM, Habr-Gama A, Silva JH, Ibrahim RE, Tudor R, Pinotti HW. Malignant melanoma of the anorectal region: report of a case and review of the literature. ABCD. Arq Bras Cirg Dig, 1989;4(4), 102-7.,88. Kantarovsky A, Kaufman Z, Zager M, Lew S, Dinbar A. Anorectal region malignant melanoma. J Surg Oncol. 1988 Jun;38(2):77-9..

Many authors classify anorectal melanomas in stages; the most common being: stage I - in situ; stage II - regional spread (inguinal lymphadenopathy); stage III - metastasis11. Campos FGCM, Habr-Gama A, Silva JH, Ibrahim RE, Tudor R, Pinotti HW. Malignant melanoma of the anorectal region: report of a case and review of the literature. ABCD. Arq Bras Cirg Dig, 1989;4(4), 102-7.,33. Dhaliwal VS, et al. Malignant melanoma of anorectal; J. Indian M.A., 1987, 85(11), 341-3..

The metastasis areas can be arranged according to its frequency: lungs, bones, liver, brain and gastrointestinal tract11. Campos FGCM, Habr-Gama A, Silva JH, Ibrahim RE, Tudor R, Pinotti HW. Malignant melanoma of the anorectal region: report of a case and review of the literature. ABCD. Arq Bras Cirg Dig, 1989;4(4), 102-7.,33. Dhaliwal VS, et al. Malignant melanoma of anorectal; J. Indian M.A., 1987, 85(11), 341-3..

The early diagnosis is essential to improve the prognosis of such an aggressive disease. Survival rates vary from 6-12% for five years44. Eng J, Sabanathan S, Whittaker M. Primary anorectal malignant melanoma. A case report. Acta Chir Scand. 1989 Jun-Jul;155(6-7):357-9.,77. Jorge E, Harvey HA, Simmonds MA, Lipton A, Joehl RJ. Symptomatic malignant melanoma of the gastrointestinal tract. Operative treatment and survival. Ann Surg. 1984 Mar;199(3):328-31.,1010. Pyper PC, Parks TG. Melanoma of the anal canal. Br J Surg. 1984 Sep;71(9):671-2.. The average survival rate in literature is 18 months1212. Slingluff CL Jr, Vollmer RT, Seigler HF. Anorectal melanoma: clinical characteristics and results of surgical management in twenty-four patients. Surgery. 1990 Jan;107(1):1-9..

Some factors can worsen the prognosis such as late diagnosis, ulceration, rich mucous vascularization, and aggressive nature of the tumors.

Since the most common complaints are enterorrhagia and anal bleeding, it is essential to perform a proctosigmoidoscopy and biopsy77. Jorge E, Harvey HA, Simmonds MA, Lipton A, Joehl RJ. Symptomatic malignant melanoma of the gastrointestinal tract. Operative treatment and survival. Ann Surg. 1984 Mar;199(3):328-31.,88. Kantarovsky A, Kaufman Z, Zager M, Lew S, Dinbar A. Anorectal region malignant melanoma. J Surg Oncol. 1988 Jun;38(2):77-9.,99. Knysh VI, Timofeev IuM, Serebriakova ES. [Treatment of melanomas of the anorectal region]. Vopr Onkol. 1987;33(3):74-8.. The pathologist should be reminded of the hypotheses, for there might be difficulties in differential diagnosis of anaplastic carcinoma and hemorrhoidal disease. It is essential to obtain other anatomopathological evidence. Some authors recommend using contrast exams along with colonoscopy33. Dhaliwal VS, et al. Malignant melanoma of anorectal; J. Indian M.A., 1987, 85(11), 341-3.,77. Jorge E, Harvey HA, Simmonds MA, Lipton A, Joehl RJ. Symptomatic malignant melanoma of the gastrointestinal tract. Operative treatment and survival. Ann Surg. 1984 Mar;199(3):328-31.,1212. Slingluff CL Jr, Vollmer RT, Seigler HF. Anorectal melanoma: clinical characteristics and results of surgical management in twenty-four patients. Surgery. 1990 Jan;107(1):1-9..

The malignant anorectal melanoma presents early metastases11. Campos FGCM, Habr-Gama A, Silva JH, Ibrahim RE, Tudor R, Pinotti HW. Malignant melanoma of the anorectal region: report of a case and review of the literature. ABCD. Arq Bras Cirg Dig, 1989;4(4), 102-7.. Mesenteric lymph nodes involvement is more common than inguinal11. Campos FGCM, Habr-Gama A, Silva JH, Ibrahim RE, Tudor R, Pinotti HW. Malignant melanoma of the anorectal region: report of a case and review of the literature. ABCD. Arq Bras Cirg Dig, 1989;4(4), 102-7.. Rectum lesions drain to the mesorectal lymph nodes and to the inferior mesenteric chain, which can occur in 33.3% of the cases. Cutaneous anal lesions drain to the superficial inguinal lymph nodes11. Campos FGCM, Habr-Gama A, Silva JH, Ibrahim RE, Tudor R, Pinotti HW. Malignant melanoma of the anorectal region: report of a case and review of the literature. ABCD. Arq Bras Cirg Dig, 1989;4(4), 102-7.. The dissemination through hematogenous pathway can reach the liver, lungs, bones, brain and gastrointestinal tract11. Campos FGCM, Habr-Gama A, Silva JH, Ibrahim RE, Tudor R, Pinotti HW. Malignant melanoma of the anorectal region: report of a case and review of the literature. ABCD. Arq Bras Cirg Dig, 1989;4(4), 102-7.. Authors diverge regarding conduct and treatment, although the recommended procedure is surgery, there are debates regarding local excision or abdominoperineal resection, and another group of authors that indicates radiotherapy and/or chemotherapy to control signs and symptoms, such as bleeding, regarding intracavitary and inguinal lymph nodes.

For some authors11. Campos FGCM, Habr-Gama A, Silva JH, Ibrahim RE, Tudor R, Pinotti HW. Malignant melanoma of the anorectal region: report of a case and review of the literature. ABCD. Arq Bras Cirg Dig, 1989;4(4), 102-7.,66. Goldman S, Glimelius B, Påhlman L. Anorectal malignant melanoma in Sweden. Report of 49 patients. Dis Colon Rectum. 1990 Oct;33(10):874-7. abdominoperineal resection can lead to a greater survival rate, especially if there is no lymph node invasion (Stage I).

The great majority of authors did not show significant difference in survival rate in patients referred to abdominoperineal resection and local excision 11. Campos FGCM, Habr-Gama A, Silva JH, Ibrahim RE, Tudor R, Pinotti HW. Malignant melanoma of the anorectal region: report of a case and review of the literature. ABCD. Arq Bras Cirg Dig, 1989;4(4), 102-7.,33. Dhaliwal VS, et al. Malignant melanoma of anorectal; J. Indian M.A., 1987, 85(11), 341-3.. There is some consensus on the fact that less recurrence is observed when abdominoperineal resection is performed, but with no statistical significant33. Dhaliwal VS, et al. Malignant melanoma of anorectal; J. Indian M.A., 1987, 85(11), 341-3..

Another aspect is that patients without compromised lymph nodes who are refered to abdominoperineal resection have a more favorable prognosis when compared to cases with compromised lymph nodes66. Goldman S, Glimelius B, Påhlman L. Anorectal malignant melanoma in Sweden. Report of 49 patients. Dis Colon Rectum. 1990 Oct;33(10):874-7.. Some authors believe that the prognosis is strictly related to the aggressive nature and early surgery44. Eng J, Sabanathan S, Whittaker M. Primary anorectal malignant melanoma. A case report. Acta Chir Scand. 1989 Jun-Jul;155(6-7):357-9..

Regarding adjuvant treatments, literature contests the success of radiotherapy (anorectal muscle non-responsiveness), as well as the lack of clarity of chemotherapy success44. Eng J, Sabanathan S, Whittaker M. Primary anorectal malignant melanoma. A case report. Acta Chir Scand. 1989 Jun-Jul;155(6-7):357-9.. Radiotherapy and hyperthermia is mentioned to control in situ disease, followed by a regression of the tumor1212. Slingluff CL Jr, Vollmer RT, Seigler HF. Anorectal melanoma: clinical characteristics and results of surgical management in twenty-four patients. Surgery. 1990 Jan;107(1):1-9.. Radiotherapy is not the treatment of choice, but it can be used as palliative treatment1212. Slingluff CL Jr, Vollmer RT, Seigler HF. Anorectal melanoma: clinical characteristics and results of surgical management in twenty-four patients. Surgery. 1990 Jan;107(1):1-9.. Immunotherapy is another method, being administered to patients that become surgically free (macroscopically) of the disease. This treatment is carried out for 4-7 months with subcutaneous injections of irradiated melanocytes with Calmette-guerin bacilli.

In conclusion, studies show the highly aggressive nature of the tumor, and the difficulty in early diagnosis and initial clinical staging. The prognosis is poor and patients face challenging metastases33. Dhaliwal VS, et al. Malignant melanoma of anorectal; J. Indian M.A., 1987, 85(11), 341-3.. Surgical outcomes are mediocre and very few live over five years11. Campos FGCM, Habr-Gama A, Silva JH, Ibrahim RE, Tudor R, Pinotti HW. Malignant melanoma of the anorectal region: report of a case and review of the literature. ABCD. Arq Bras Cirg Dig, 1989;4(4), 102-7..

REFERENCES

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    Campos FGCM, Habr-Gama A, Silva JH, Ibrahim RE, Tudor R, Pinotti HW. Malignant melanoma of the anorectal region: report of a case and review of the literature. ABCD. Arq Bras Cirg Dig, 1989;4(4), 102-7.
  • 2
    Clemmensen OJ, Fenger C. Melanocytes in the anal canal epithelium.Histopathology. 1991 Mar;18(3):237-41.
  • 3
    Dhaliwal VS, et al. Malignant melanoma of anorectal; J. Indian M.A., 1987, 85(11), 341-3.
  • 4
    Eng J, Sabanathan S, Whittaker M. Primary anorectal malignant melanoma. A case report. Acta Chir Scand. 1989 Jun-Jul;155(6-7):357-9.
  • 5
    García Montes JM, Jiménez Sáenz M, Hernández Peña M, Herrerías Gutiérrez JM.[Anorectal melanoma]. Rev Esp Enferm Apar Dig. 1989 Aug;76(2):173-5.
  • 6
    Goldman S, Glimelius B, Påhlman L. Anorectal malignant melanoma in Sweden. Report of 49 patients. Dis Colon Rectum. 1990 Oct;33(10):874-7.
  • 7
    Jorge E, Harvey HA, Simmonds MA, Lipton A, Joehl RJ. Symptomatic malignant melanoma of the gastrointestinal tract. Operative treatment and survival. Ann Surg. 1984 Mar;199(3):328-31.
  • 8
    Kantarovsky A, Kaufman Z, Zager M, Lew S, Dinbar A. Anorectal region malignant melanoma. J Surg Oncol. 1988 Jun;38(2):77-9.
  • 9
    Knysh VI, Timofeev IuM, Serebriakova ES. [Treatment of melanomas of the anorectal region]. Vopr Onkol. 1987;33(3):74-8.
  • 10
    Pyper PC, Parks TG. Melanoma of the anal canal. Br J Surg. 1984 Sep;71(9):671-2.
  • 11
    Singh W, Madaan TR. Malignant melanoma of the anal canal. Am J Proctol. 1976 Feb;27(1):49-55.
  • 12
    Slingluff CL Jr, Vollmer RT, Seigler HF. Anorectal melanoma: clinical characteristics and results of surgical management in twenty-four patients. Surgery. 1990 Jan;107(1):1-9.
  • 13
    Wong JH, Cagle LA, Storm FK, Morton DL. Natural history of surgically treated mucosal melanoma. Am J Surg. 1987 Jul;154(1):54-7.

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Publication Dates

  • Publication in this collection
    Nov-Dec 2016

History

  • Received
    04 Feb 2016
  • Accepted
    02 Aug 2016
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