The impact of (18)F-FDG-PET/CT on Merkel cell carcinoma management: a retrospective study of 66 scans from a single institution.
OBJECTIVE
Merkel cell carcinomas (MCC) are neuroendocrine skin tumours frequently responsible for lymph node recurrence and metastatic disease and for which optimal management remains to be defined. The objective of this study was to evaluate the impact of (18)F-fluorodeoxyglucose ((18)F-FDG)-PET/computed tomography (CT) on the staging and treatment of MCC patients.


METHODS
Twenty-three patients with a histologic diagnosis of MCC explored by (18)F-FDG-PET/CT between 2004 and 2012 were retrospectively included in the study. The detection of new lesions and the change in tumour staging and treatment were evaluated. For each patient, the (18)F-FDG-PET/CT results were compared with histological, clinical and imaging data.


RESULTS
Sixty-six (18)F-FDG-PET/CT scans were performed at initial presentation (n=18), during subsequent monitoring (n=34) or during evaluation of chemotherapy response (n=14). The sensitivity, specificity and positive and negative predictive values of the (18)F-FDG-PET/CT were 97, 89, 94 and 94%, respectively. Two false-positive results (lymphadenitis) and one false-negative result (regional metastatic lymph nodes) were accounted for. Lesions not detected clinically or by conventional imaging techniques were found in 44% of the 52 (18)F-FDG-PET/CTs performed at initial presentation and subsequent monitoring, with, respectively, 50 and 41% of scans identifying new lesions. At initial presentation, (18)F-FDG-PET/CT led to a change in tumour staging in 39% of patients. Patient management was modified by (18)F-FDG-PET/CT results in one-third of patients (33% of patients at initial presentation, 32% during subsequent monitoring and 36% during evaluation of chemotherapy response). F-FDG-PET/CT incidentally detected four additional histologically confirmed cancers.


CONCLUSIONS
This retrospective study confirms the important impact of (18)F-FDG-PET/CT on the management of MCC patients.
aDepartments of Nuclear Medicine and Medical Oncology, Comprehensive Cancer Center ICO Paul Papin, Angers, bDepartment of Nuclear Medicine, University Hospital, Angers, France.
Adeline
A
George
Sylvie
S
Girault
Aude
A
Testard
Rémy
R
Delva
Patrick
P
Soulié
Olivier-F
OF
Couturier
Olivier
O
Morel
D000368:Aged; D000369:Aged, 80 and over; D015266:Carcinoma, Merkel Cell / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000473:pathology; D005260:Female; D019788:Fluorodeoxyglucose F18; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D064847:Multimodal Imaging; D009367:Neoplasm Staging; D049268:Positron-Emission Tomography; D012008:Recurrence; D012189:Retrospective Studies; D012878:Skin Neoplasms / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000473:pathology; D014057:Tomography, X-Ray Computed
D019788:Fluorodeoxyglucose F18