Spontaneous regression of a metastatic melanoma pulmonary deposit following biopsy.

Spontaneous complete and partial regression of metastatic melanoma is poorly understood, and is a rare phenomenon with less than 80 cases reported since 1866. Several correlations have been noted such as systemic or local infections, operative trauma, hormonal influences, nutrition and immunologic factors. We present FDG PET and CT findings in a patient with multiple pulmonary metastases of melanoma, one of which underwent regression following biopsy. We suggest immune system modulation, triggered by biopsy, could have played a role, although the precise mechanism remains unknown.