Rare malignant melanotic nerve sheath tumors of the upper limb nerves: utility of high frequency ultrasonography in preoperative imaging Skeletal Radiology Springer Nature Link Melanoma metastasis Radiology Case Radiopaedia.org Tumoral Melanosis New England Journal of Medicine This is a very rare case of metastatic oral mucosal melanoma to the colon with an unusual presentation mimicking melanosis coli. The colonoscopy findings show no mass effect but multiple hyperpigmented lesions