Primary anorectal malignant melanoma: report of a case

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

Malignant melanomas are rare aggressive tumours originating from the pigment-producing melanocytes. In our study, a review of the literature and a retrospective analysis of patients undergoing surgery at our clinic due to anorectal malignant melanoma were performed. The information of 6 patients undergoing surgery in our clinic due to anorectal malignant melanoma between January 2010 and January 2018 was retrieved retrospectively. The patients were assessed regarding demographic data, physical examination and imaging findings, the surgical method performed, postoperative complication, histopathological findings, oncological treatment and follow-up results. Four of the patients were female and 2 were male and the mean age was 61.6 (46–83) years. Two patients (33%) had liver metastases at the time of initial presentation. Abdominoperineal resection (APR) was performed in all patients 3 with laparoscopic method. The mean length of hospital stay was recorded to be 6.5 ± 1 days (5–12 days). Adjuvant chemotherapy and radiotherapy were administered in all patients. Also, interferon treatment was administered in one patient additionally. During the follow-up, 4 patients died due to extensive metastatic disease determined approximately in the 13th month. Two patients with regular follow-up are well and free of disease and their mean postoperative lifetime has been determined to be 12.5 months (6–26 months). Anorectal malignant melanomas (ARMM) are rare but aggressive tumours. The treatment should be focused on minimizing morbidity and maximizing the quality of life and function while removing the gross tumour.

JOURNAL CLUB: Primary Anorectal Melanoma: MRI Findings and Clinicopathologic Correlations

OBJECTIVE

The purpose of this study is to evaluate the MRI features of primary anorectal malignant melanoma and to correlate these features with its clinical and pathologic characteristics.

MATERIALS AND METHODS

The medical records of 12 patients (five men and seven women; mean age [± SD], 60.8 ± 10.0 years) with pathologically proven primary anorectal melanoma were retrospectively reviewed. MRI findings were analyzed to determine the shape, size, distance from the anal verge, presence of perirectal or anal infiltration, signal intensity on T1- and T2-weighted images, presence of diffusion restriction, contrast enhancement pattern of the lesion, presence of lymphadenopathy, and occurrence of bowel obstruction. Subsequent follow-up data for the patients were recorded.

RESULTS

The most common presentation was hematochezia (41.7% of patients). Common findings on MRI included a large intraluminal polypoid mass (75.0% of lesions) with little perirectal or anal infiltration (100.0%), T1 hyperintensity (66.7%), high T2 signal intensity (54.5%) or mixed T2 signal intensity (45.5%), restricted diffusion (100.0%), and hyper-enhancement (100.0%). The mean length, width, and depth of these masses were 3.5, 2.9, and 2.3 cm, respectively. The mean distance from the anal verge was 1.8 cm. Lymphadenopathy was frequently identified (75.0% of cases), with lymph nodes larger than 2 cm noted in 28.5% of cases and most commonly involving the perirectal area (77.8% of cases). No colonic obstructions were observed. The mean patient follow-up was 32.7 months. A total of 25.0% of patients died as a result of disease progression.

CONCLUSION

The possibility of the presence of anorectal melanoma should be considered for patients with a bulky intraluminal polypoid mass in the anorectum without colonic obstruction, with the mass showing T1 hyperintensity, high or mixed signal T2 intensity, hyperenhancement, minimal perirectal or anal infiltration, and lymphadenopathy.

Anorectal malignant melanoma: preoperative usefulness of magnetic resonance imaging

Magnetic resonance imaging (MRI) findings in three patients with primary anorectal malignant melanoma are described. Two patients had melanotic and one had amelanotic anorectal melanoma. The findings of MRI with a pelvic coil and an endorectal coil were consistent with pathologic findings. MRI with a pelvic coil demonstrated the melanotic component as high signal intensity on T1-weighted imaging. MRI with a pelvic coil and an endorectal coil was useful for staging anorectal melanoma. This article describes the initial report of the use of an endorectal coil for malignant melanoma of the anorectum.