False-positive findings on (131)I whole-body scans because of posttraumatic superficial scabs.
Nonspecific (131)I uptake may affect both the specificity and the accuracy of whole-body scanning (WBS) performed after (131)I administration in the follow-up of thyroid carcinoma after thyroidectomy. We report a newly identified cause of false-positive WBS findings: posttraumatic superficial scabs.


METHODS
Four patients who underwent thyroidectomy for differentiated thyroid carcinoma were studied after therapeutic administration of 3,700 MBq (131)I.


RESULTS
WBS revealed an area of uptake in the lower limbs, in a site corresponding to a slight abrasion of the skin that had incidentally occurred between a few hours before and 24 h after radioiodine administration. In 2 patients, a radioiodine concentration in the scab was shown by the disappearance of the radioactivity in the leg after removal of the scab and by detection of radioactivity in the collected material.


CONCLUSIONS
Posttraumatic superficial scabs may be a cause of false-positive WBS findings. High (131)I doses, although providing increased sensitivity, may also increase the number of false-positive results.
Regalbuto
Concetto
C
Department of Internal Medicine, Garibaldi Hospital, University of Catania, Catania, Italy. segmeint@mbox.unict.it
Buscema
Massimo
M
Arena
Salvatore
S
Vigneri
Riccardo
R
Squatrito
Sebastiano
S
Pezzino
Vincenzo
V
D018263:Adenocarcinoma, Follicular / Q000000981:diagnostic imaging* / Q000532:radiotherapy / Q000556:secondary / Q000601:surgery; D000328:Adult; D002291:Carcinoma, Papillary / Q000000981:diagnostic imaging* / Q000532:radiotherapy / Q000556:secondary / Q000601:surgery; D005189:False Positive Reactions; D005260:Female; D006801:Humans; D007457:Iodine Radioisotopes / Q000627:therapeutic use; D022125:Lacerations / Q000000981:diagnostic imaging*; D008197:Lymph Node Excision; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000000981:diagnostic imaging; D011877:Radionuclide Imaging; D012680:Sensitivity and Specificity; D013964:Thyroid Neoplasms / Q000000981:diagnostic imaging* / Q000532:radiotherapy / Q000601:surgery; D013965:Thyroidectomy; D014945:Wound Healing
D007457:Iodine Radioisotopes