Several explanations have been postulated for delayed metastasis of differentiated tumors. Alexander presented an intriguing pathogenic hypothesis proposing that clusters of dividing cells lead to an equilibrium between cell death and proliferation, or that the tumor cells remain in a state of rest for long periods without losing their viability before renewed tumor growth is induced by the somatic transformation of the cancer cells . We report a rare case of a solitary pulmonary metastasis found 5 years after curative resection of primary esophageal melanoma. Radical surgical resection with en bloc lymphadenectomy is the treatment of choice of primary melanoma of the oesophagus, with a five year survival of 4.25% . Although laser, radiotherapy, chemotherapy, immunotherapy have not proven to be beneficial, they may play a palliative role if surgery is not applicable for advanced stages or poor functional status . Of the approximately 200 cases that have been reported to date, only about 30% of the patients survived more than 1 year after the initial diagnosis . The aggressive biological behavior of this disease, the advanced stage at the time of diagnosis and the lack of effective therapy contribute to its poor prognosis. PMME is a very aggressive tumor and esophagogastroduodenoscopy, endoscopic ultrasonography and CT scan are required to complete the preoperative staging. Chalkiadakis demonstrated that distant metastases are present in 78% of the patients suffering from PMME . The most common site of metastases is the liver (31%), followed by mediastinum (29%), lung (17%), brain (13%) and other intra-abdominal organs. Detection rate of metastatic disease identification using immunoscintigraphy with 99 mTc-labeled melanoma monoclonal AB is 95% for bone lesions, 91% for liver, 78% for lymph node metastases, 62% for brain, 62% for spleen and 58% for lung [14, 15]. This technique cannot identify deposits of 1 cm or less in size [14, 15]. Although it has been demonstrated that radical resection increases the survival compared to local treatment, 5-year survival is less than 5%, mainly due to the advanced state of the disease at the time of diagnosis . Various drugs, alone or in combination, including vinblastine, bleomycin, lomustine, vincristine and recently recombinant interferon-alpha and interleukin-2, have been used with varying results as palliative treatment of cutaneous melanoma [17–20]. Combination of cisplatin, carmustine, dacarbazine and tamoxifen have also been studied with promising results in cutaneous melanoma patients with advanced disease . Several investigators have supported the above findings and the role of tamoxifene as drugs modulator [22–24]. Nevertherless, none of these regimens have been used in esophageal melanomas which is considered to be a radioresistant tumor, and chemotherapy, external beam and intracavitary radiotherapy may only have a palliative role . At the time of diagnosis, clinically, surgically or pathologically detectable metastases were present in 40.9% of patients. The overall survival is 9.8 months with five year survival rate of 1.69%. Only 33% of patients survive for more than 1 year after diagnosis. Deaths are disease-related in 75–85% of cases .
Although the reason for the delayed presentation of the metastatic lesion remains unclear, the case report we described demonstrates that patients with primary melanoma of the oesophagus surgically treated should be carefully followed up.