case_images: PMC8692289_01
case_images: Case timeline detailing therapeutic interventions and clinical responses.
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case_images: PMC8692289_01_fimmu-12-788499-g001.jpg
case_images: f1
case_images: After his metastatic melanoma diagnosis, pembrolizumab (200 mg at 3-week intervals) monotherapy was initiated in December of 2018 ( Figure 1 ). He completed 20 Gy in five fractions over 7 days to the sacral metastasis in mid-October 2019 and received two more doses of pembrolizumab with vedolizumab with the last dose in early November 2019 ( Figure 1 ).
case_images: PET/CT scout images over the course of the patient's treatment. The blue arrows in the figure show the RLL nodule with good response to initial pembrolizumab monotherapy in February 2019 from the baseline scan in November 2018. However, the red arrows demonstrate a site of progression in the right pelvic sidewall through initial pembrolizumab monotherapy representing mixed response to initial pembrolizumab monotherapy. The September 2019 scan, after a break in pembrolizumab therapy for colitis, clearly shows progression of these lesions along with emergency of new, multifocal liver metastases (outlined with blue line). In October 2019, palliative RT was delivered to sacral metastatic lesion (signified by lightning symbol in the timeline). Subsequent PET/CT in January 2020 and July 2021 showed complete and durable response after completion of RT.
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case_images: PMC8692289_01_fimmu-12-788499-g002.jpg
case_images: f2
case_images: After four doses of pembrolizumab, restaging PET imaging in February 2019 demonstrated a mixed response with a 74% decrease in size of his dominant right lower lobe (RLL) nodule (from 4.2 x 3.6 cm to 2.2 x 1.8 cm with SUV decrease 31% from 9.4 to 6.5), a decrease in size of the left lower lobe (LLL) nodule by 80% (from 1.6 x 2.2 cm to 0.9 x 0.8 cm with no residual metabolic activity), but a 33% increase in size of right obturator lymph node (from 1 cm to 1.5 cm with an SUV increase of 83% from 2.1 to 12.2), and new sub-centimeter hypermetabolic pelvic sidewall node ( Figures 2 ,  3 ). PET scans were repeated every 3 to 4 months which continued to show complete metabolic response to all sites ( Figures 2 ,  3 ) of systemic disease as well as near-complete radiographic response via CT.
case_images: PET/CT scans over the course of the patient's treatment. The blue arrow in the top panel shows RLL nodule with good response to initial pembrolizumab monotherapy from the baseline scan in November 2018. The red arrow in the bottom panel shows a site of progression in the right pelvic sidewall through initial pembrolizumab monotherapy representing mixed response to initial pembrolizumab monotherapy. Palliative RT was delivered October 2019 to sacral metastasis (signified by lightning symbol). The blue line in the middle panel outlines multifocal progressive disease in the liver seen on the September 2019 PET/CT after break in therapy due to pembrolizumab-related colitis. PET/CT in January 2020 and September 2021 show complete metabolic response.
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case_images: PMC8692289_01_fimmu-12-788499-g003.jpg
case_images: f3
case_images: After four doses of pembrolizumab, restaging PET imaging in February 2019 demonstrated a mixed response with a 74% decrease in size of his dominant right lower lobe (RLL) nodule (from 4.2 x 3.6 cm to 2.2 x 1.8 cm with SUV decrease 31% from 9.4 to 6.5), a decrease in size of the left lower lobe (LLL) nodule by 80% (from 1.6 x 2.2 cm to 0.9 x 0.8 cm with no residual metabolic activity), but a 33% increase in size of right obturator lymph node (from 1 cm to 1.5 cm with an SUV increase of 83% from 2.1 to 12.2), and new sub-centimeter hypermetabolic pelvic sidewall node ( Figures 2 ,  3 ). Following a 5-month cessation in melanoma therapy, a PET scan was repeated in September 2019 and revealed numerous new liver metastases, a new sacral metastasis, two new lung nodules, and an increase in PET avidity of RLL nodule by 57% compared to February PET ( Figure 3 ). As a result of this unexpected finding, a PET scan was ordered for restaging purposes and revealed a near-complete metabolic response with complete resolution of FDG activity in metastatic liver disease, as well as improved pulmonary, pelvic, and sacral metastatic disease ( Figure 3 ). PET scans were repeated every 3 to 4 months which continued to show complete metabolic response to all sites ( Figures 2 ,  3 ) of systemic disease as well as near-complete radiographic response via CT.