Case of the Quarter - 2016 Q2

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Clinical History

Patient with metastatic melanoma, on anti-PD1 inhibitor therapy with favourable response. ? ongoing response.

Findings

FDG PET/CT imaging was performed from the base of skull to lower legs with low dose CT attenuation correction and image fusion. Comparison is made to the previous scan performed 3 months prior.

There has been a further reduction in activity associated with the right pelvic node (SUVmax was 5.8 and is now 5.2) and right hilar node (SUVmax was 3.7 and is now 3.5).

There is progressive increasing uptake which is now intense in the soft tissues around the shoulders and knees (synovitis), the lumbar spine posterior and anterior interspinous spaces (bursitis) and in relation to the soft tissues around the hips and ischial tuberosities (enthesopathy). There is slightly prominent uptake in the aortic arch.

No other significant sites of abnormal nodal, visceral or skeletal activity are demonstrated elsewhere.

Interpretation

Scan findings are in keeping with stable appearances in previous known metastatic disease. The increasing soft tissue abnormalities are inflammatory and likely to be due to polymyalgia rheumatica.

Key Teaching points and Discussion

References

Garel B, et al. Pembrolizumab-induced polymyalgia rheumatica in two patients with metastatic melanoma. Joint Bone Spine. 2016 Apr 25.doi: 10.1016/j.jbspin.2016.01.007.

Goldstein BL, Gedmintas L, Todd DJ. Drug-associated polymyalgia rheumatica/giant cell arteritis occurring in two patients after treatment with ipilimumab, an antagonist of ctla-4. Arthritis Rheumatol. 2014 Mar;66(3):768-9. doi: 10.1002/art.38282.

Hofman MS, Fluorodeoxyglucose positron emission tomography/computed tomography: a 'one stop shop' for diagnosing polymyalgia rheumatica BMJ 2013;347:f6937. http://goo.gl/Hrj9y4

Naidoo J et al, Toxicities of the anti-PD-1 and anti-PD-L1 immune checkpoint antibodies, Ann Oncol. 2015;26(12):2375. http://annonc.oxfordjournals.org/content/26/12/2375.long