Unknown primary melanoma shows only metastatic malignant malanoma without obvious primary tumor. These unusual instances of unknown primary melanoma have reported incidences of 1.0~8.7%. This 51 year old patient had many intra-abdominal and mesenteric masses without visible primary tumor. The most commonly accepted explanation for unknown primary melanoma is spontaneous regression of a primary skin lesion.
Incidence ; Neoplasm Metastasis