Anorectal Malignant Melanoma: Retrospective Analysis of Six Patients and Review of the Literature

Anorectal melanoma: systematic review of the current literature of an aggressive type of melanoma

Anorectal melanoma (ARM) is a rare malignancy often associated with a poor prognosis due to its late diagnosis and aggressive biological behavior. This review aims to comprehensively investigate ARM's diagnosis, management, and treatment, emphasizing its clinical characteristics, laboratory findings, and implications for patient prognosis. A systematic literature search was conducted in PubMed, Embase, and Cochrane CENTRAL databases from inception to 1 July 2024. This review synthesizes existing literature to provide a comprehensive understanding of this rare primary malignancy. A total of 110 articles reporting on 166 patients were included. Gender data were available for 131 cases, comprising 67 females (51.1%) and 64 males (48.9%). The median age was 66 years. The overall median time to diagnosis was 4 months for anal melanoma, 3 months for rectal melanoma, and 4 months for anorectal junction melanoma. The clinical presentation was nodular in 98.2% of cases. Pre-diagnosis symptoms included bleeding in 84.9% of cases, mucous elimination (6%), pain (68.7%), tenesmus (16.9%), and changes in bowel movements (28.5%). Overall survival (OS) was reported in 82 cases, with a median OS of 11 months: 11 months for anal melanoma, 7 months for rectal melanoma, and 12 months for anorectal junction melanoma. ARM is a rare and aggressive melanoma subtype often diagnosed at an advanced stage, leading to a poor prognosis. A female predominance was observed, consistent with other mucosal melanomas. Anal melanoma exhibited better progression-free survival, and OS compared to rectal and anorectal junction melanoma.

Early-Stage Primary Rectal Melanoma: A Case Report

Malignant primary rectal melanomas (PRM) are rare tumors. Their diagnosis is frequently delayed as these lesions are often mistaken for benign diseases, resulting in extremely poor overall survival. Histological evaluation with special immunohistochemical (IHC) stains is often indispensable for a definitive diagnosis. The main treatment for this condition involves surgical resection. Adjuvant therapy has also been long recommended. We discuss the case of a 60-year-old woman who presented with changes in bowel habits, anal pain, and perineal burning with no bleeding. A digital rectal examination revealed a nodular mass extending 5 cm from the anal verge. Rectosigmoidoscopy demonstrated an ulcerated polypoid tumor extending 4 cm from the anal verge and over 5 cm into the lower rectum. Biopsy and IHC tests confirmed the diagnosis of rectal melanoma. The patient was successfully managed with surgery followed by external beam radiotherapy and a complete response was achieved after 10 months of follow-up.

Effect of surgical treatment for anorectal melanoma: a propensity score-matched analysis of the Surveillance, Epidemiology, and End Results programme data

OBJECTIVE

Anorectal melanoma (AM) is a rare but aggressive tumour with limited information in the existing literature. This study aimed to assess the effect of surgical treatment for AM and predict the prognosis of affected patients.

DESIGN

A retrospective cohort study.

SETTING

Data of patients diagnosed with AM between 1975 and 2016 in the USA were collected from the Surveillance, Epidemiology, and End Results (SEER) database.

PARTICIPANTS

This study enrolled a total of 795 patients with AM from the SEER database and the validation cohort comprised 40 patients with AM enrolled from Chinese institutes.

PRIMARY AND SECONDARY OUTCOME MEASURES

Overall survival (OS) and AM-specific survival (AM-SS).

RESULTS

A total of 795 patients with AM diagnosed between 1975 and 2016 were enrolled in this study. Data over the past four decades showed a trend of increase in incidence rate. A nomogram based on a multivariate Cox regression model was generated to predict AM-SS. The C-index of the nomogram was 0.74 (95% CI 0.71 to 0.77) on internal verification. In the validation cohort, the C-index of the nomogram was 0.72 (95% CI 0.68 to 0.76). The results of propensity score matching (PSM) analysis showed that patients who underwent surgical treatment achieved significant survival (OS: log-rank=17.41, p<0.001; AM-SS: log-rank=14.55, p<0.001). Patients who underwent surgery were stratified into local and extended surgery subgroups. AM-SS and OS were also compared after PSM, but the results were not significantly different between the two surgery subgroups (all p>0.05).

CONCLUSIONS

The nomogram based on the analysis of SEER data showed good performance in predicting OS and AM-SS. Patients with AM can benefit from surgery; however, extensive surgery and appendectomy may not improve AM-SS or OS.

Locally advanced anorectal malignant melanoma in septuagenarian patient treated by laparoscopic abdominoperineal resection: A case report

Introduction

Anorectal malignant melanoma (ARMM) is a rare disease with a poor prognosis. In cases involving locally advanced disease, the treatment strategy is difficult, especially in octogenarian patients, because the prognosis is poor, despite the corresponding decrease or loss of the anal function.

Presentation of case

A 78-year-old woman was admitted to a local hospital with chief complaints of severe anal discomfort due to an egg-sized tumor that was protruding out of the anus and melena. A diagnosis of ARMM was confirmed based on the examination of biopsy specimens and imaging study showed swollen lymph nodes on the dorsal side of the middle rectum and left internal iliac lymph nodes.

Laparoscopic abdominoperineal resection with left lateral lymph node dissection was performed. The examination of the resected specimen revealed two polypoid tumors with a maximum diameter of 38 mm and 14 mm with a metastatic lymph node of 62 mm in the mesorectum. The postoperative course was uneventful. Relapse and local recurrence free survival without any complaints was obtained for more than 12 months.

Discussion

With respect to locoregional disease control, it has been reported that abdominoperineal resection can obtain better control of local disease in comparison to local resection. Laparoscopic surgery is advantageous in its facilitation of an early postoperative recovery for elderly patient.

Conclusion

Laparoscopic abdominoperineal resection may control locoregional disease and improve the patient's QOL with early postoperative recovery. —even in septuagenarian patients—may become a treatment strategy for advanced ARMM.

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Anorectal malignant melanoma is a rare disease with a poor prognosis.

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Surgical procedure for anorectal malignant melanoma is controversial.

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APR may achieve better local control for advanced anorectal malignant melanoma.

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Laparoscopic surgery is advantageous in its facilitation of an early recovery for elderly patient.

Anorectal Melanoma-Brownish Black Mass Not Always a Hemorrhoid

The non-specific clinical symptoms of anorectal brownish-black mass do not help to differentiate colorectal cancer, hemorrhoids, rectal ulcers which result in a delayed diagnosis or lead to inadequate management of lethal anorectal melanoma. Primary malignant melanoma of the anorectal region is an uncommon tumor, constituting approximately 1% of anal canal tumors which may be misdiagnosed clinically as hemorrhoids. Because of aggressive behavior and poor prognosis, efficient and prompt diagnosis is required in these cases. We report 2 cases of this rare tumor.

Primary Anorectal Amelanotic Melanoma: The First Case Report from Saudi Arabia

Anorectal melanomas are exceptionally uncommon and only 30% of anorectal melanomas are amelanotic. We report here a case of an anorectal amelanotic melanoma in a female patient. An 84-year-old patient complained of anal mass for 3 months. On examination, there was a 7.0 cm mass prolapsing through the anus that was pale-pink in color. Abdominal, pelvic, and chest computed tomography (CT) showed rectal wall thickening with an eccentric polypoid soft tissue density mass, and left inguinal and presacral lymph node enlargement along with a small nodule in the lower lobe of the left lung, likely representing metastatic deposit. Microscopic examination revealed a piece of skin with hyperplastic squamous epithelium with surface ulceration. The dermis and underlining tissue were showing infiltration by malignant sheets and nests of ovoid and spindle shape cells with prominent nucleolus and high mitotic s. Immuno-staining for HMB-45, S-100, and Melan-A was positive, and it was negative for P63, CK 5/6, and Pan-CK, thus confirming it as an anorectal amelanotic melanoma, and not an epithelial tumor. This is the first case of an amelanotic anorectal melanoma reported from Saudi Arabia.