Anorectal Melanoma: An Unusual Cause of Rectal Bleeding

Amelanotic Malignant Melanoma With Atypical Divergent Neuroendocrine Differentiation: A Report of an Unusual and Rare Case of Anorectal Bleeding

Melanocytes located between the anal transition zone and the dentate line of the anal canal can give rise to the uncommon malignant tumor known as anal melanoma. It has a fast-paced clinical course and can masquerade as several common anorectal symptoms, such as hemorrhoids or rectal ulcers. In melanoma, divergent differentiation is a very uncommon phenomenon. The diagnosis of melanoma is difficult with histopathology sections alone (hematoxylin and eosin, H&E). Special stains and ancillary immunohistochemistry investigations are useful in these situations. A 60-year-old female patient presented to the surgical outpatient department with complaints of anorectal bleeding. After clinical evaluation, a growth in the anorectal region was identified, and a biopsy was taken from the growth. Histopathological and subsequent immunohistochemical analysis of the biopsy material was done at the Department of Pathology. A diagnosis of amelanotic melanoma with atypical and divergent neuroendocrine differentiation involving the anorectal region was rendered. Histologically, this tumor showed extremely pleomorphic polygonal to elongated spindle cells that co-expressed neuroendocrine markers and were positive for S100, HMB-45, and Melan-A. This case presented many diagnostic challenges at both the histomorphological level and the immunohistochemical expression profile analysis. We will go into great depth regarding the diagnostic challenges in this instance and provide an outline of our approach. The immunohistochemical and prognostic importance of this case will also be covered.

Efficacy and prognosis of surgical treatment in ARMM and its effects on immune and inflammatory profiles

The aim of the present study was to investigate the efficacy and prognosis of surgical treatment in anorectal malignant melanoma (ARMM) as well as its effects on immune and inflammatory profiles. A total of 64 patients with ARMM were enrolled and divided into control group (n=32) and observation group (n=32) based on different therapeutic methods. Patients in the observation group underwent wide local excision, while those in the control group were given non-surgical treatment. The immune function was compared between the two groups after treatment. The expression levels of serum IL-17, IL-23 and vascular endothelial growth factor (VEGF) were compared between the groups before and after treatment. Patients were followed up for 5 years to observe the recurrence and survival rates in the two groups. Compared with those in the control group, the levels of cluster of differentiation (CD)3⁺, CD4⁺ and CD4⁺/CD8⁺ were increased, while the level of CD8⁺ was reduced in the observation group (P<0.05). The levels of serum IL-17, IL-23 and VEGF were significantly lower in both groups at 4, 6 and 8 weeks after treatment than those before treatment, and the decrease was more obvious in the observation group (P<0.05). The observation group exhibited a notably elevated 5-year survival rate and a remarkably decreased recurrence rate in comparison with the control group (P<0.05). For ARMM, surgical treatment is more effective than non-surgical treatment, which has less effect on immune function, is able to reduce serum IL-17, IL-23 and VEGF levels, lower recurrence rate, improve patient survival rate, and plays a certain positive role in prolonging the survival time of ARMM patients.

Peritoneal Carcinomatosis Arising from Primary Anorectal Melanoma

Anorectal melanoma is a rare and aggressive malignancy with a poor prognosis. Anorectal melanoma makes up approximately 1 to 3% of all anorectal malignancies. There are no known risk factors for anorectal melanoma. Patients frequently experience a delay in diagnosis due to multiple factors including nonspecific symptoms and misdiagnosis for other benign entities. Anorectal melanoma has a high potential for distant metastases and radiographic imaging plays a key role in evaluating for metastatic disease. Common sites for metastasis include pelvic lymph nodes, lungs, liver, skin, and brain. We present a case report of a 75 year old female with a history of transanal excision of primary anorectal melanoma who presented with increasing abdominal pain and distention. Computed tomography scan of the abdomen and pelvis showed metastatic disease to the peritoneum with findings of extensive peritoneal carcinomatosis, demonstrating the aggressive nature of anorectal melanoma.