Primary versus Metastatic Gastrointestinal Melanoma: A Rare Case and Review of Current Literature

Figure 1

Extended right hemicolectomy specimen containing a 5.6 cm exophytic, partially obstructing lesion (a). Histology of colon lesion showing sheets of medium- to large-sized tumor cells with irregular nuclear contours and vesicular nuclei, intermixed with numerous mitotic figures ((b), hematoxylin-eosin, 400x). Immunohistochemistry of colon lesion diffusely positive for melan-A (c). PET scan showing areas of metastatic disease (left renal mass, L1 vertebral body), but prominent intensity of the left inguinal region and left anterior thigh (d). Endoscopy showing one of many pigmented lesions throughout the stomach (e).