A case of metastatic melanoma in the liver mimicking colorectal cancer with synchronous liver metastasis.

INTRODUCTION AND IMPORTANCE: Colorectal cancer (CRC) presenting with synchronous liver metastasis is relatively common, occurring in approximately 20 % of patients1. Herein we report an atypical case of a patient who presented with a new, obstructing colon mass with synchronous liver metastasis, biopsy proven to be malignant melanoma. CASE PRESENTATION: An 81-year-old male presented to the hospital emergency department with abdominal pain, diarrhea, and 30-pound unintentional weight loss over the past 4 months. Investigations revealed an obstructing cecal mass with multiple large, hypodense hepatic masses suspicious for metastatic disease. A multidisciplinary evaluation ensued, and the decision was made to treat with palliative intent. The patient was surgically treated with a diverting stoma and an intraoperative biopsy of the hepatic masses demonstrated metastatic melanoma. The patient did report a remote history of malignant melanoma and underwent curative-intent resection a decade earlier. There was no evidence of a new primary cutaneous melanoma. A tentative plan for checkpoint inhibitor therapy was discussed, but his medical issues worsened, and the patient died before any anti-cancer therapy could be started. CLINICAL DISCUSSION: The clinical picture of obstructing colon mass with synchronous liver masses most commonly represents a colon primary with synchronous liver metastasis. The capacity for melanoma to mimic other pathologies is unusual but has been described, with case reports describing metastasis to the eye, biliary hilum, liver, pancreas, colon, small bowel, and brain. This case serves as a good reminder that melanoma may mimic a variety of oncologic presentations, even after a very long disease-free interval. CONCLUSION: Our patient suspected to have metastatic colon cancer was found instead to have metastatic melanoma, with significantly different therapeutic options and prognosis.

The effects of the posterior sagittal approach on rectal function (experimental study).

The posterior sagittal transsphincteric approach has been used for the treatment of anorectal malformations in children and for other acquired conditions mainly in adults. Although the reports on clinical results indicate that the division of the sphincteric mechanism does not harm the function of the voluntary muscles, there are no experimental objective evaluations of the rectal function and fecal continence after a posterior sagittal transsphincteric approach. Sixteen dogs were studied forming four groups of four animals each. Group I was subjected to a posterior sagittal approach only without opening of the rectum. Group II underwent a posterior sagittal approach plus posterior and anterior rectotomy. Group III underwent a posterior sagittal approach plus a perirectal dissection, and group IV underwent only a perirectal dissection without posterior sagittal incision. All animals were evaluated clinically and manometrically preoperatively and postoperatively and were followed up to 12 weeks. Results indicated that the perirectal dissection with and without posterior sagittal incision provoked the most severe changes in bowel control and manometric parameters. Posterior sagittal approach with or without rectotomy provoked minimal or no changes in bowel function and rectal manometry. This experimental study supports the clinical experiences and indicates that the posterior approach does not interfere with the function of the sphincteric mechanism.