Metastatic melanoma of the right axilla developing 22 years after the treatment of primary cutaneous melanoma of the right thumb: Probability of "ultra-late recurrence"

The recurrence of late onset cutaneous melanoma is not a common phenomenon. Ultra-late recurrence, which is defined as recurrence more than 15 years after initial treatment, is especially rare. A patient presented with a 2-month history of firm subcutaneous tumors in his right axilla. He had been diagnosed with melanoma of his right thumb 22 years ago, treated with amputation of the right thumb and partial ipsilateral axillary node dissection; there had been no previous recurrences. The present biopsy of the right axilla revealed lymph nodes occupied by melanoma cells. Distant metastasis was revealed on PET-CT and included the lung, pancreas and abdominal lymph nodes. Three possible explanations were proposed: (i) ultra-late recurrence of primary melanoma; (ii) axillary metastases from primary malignant melanoma of internal organ(s); (iii) axillary metastases of another unknown primary cutaneous melanoma which had completely regressed. After careful consideration, we concluded the most probable diagnosis to be "ultra-late recurrence" and report this case with reviews of late and ultra-late recurrence of melanoma.