Cutaneous and Subcutaneous Imaging on FDG-PET

Abstract

F-18 fluorodeoxyglucose positron emission tomography (F-18 FDG PET) has been shown to be useful in the evaluation of many tumors due to its high sensitivity and specificity. However, false-positive interpretations may occur from benign subcutaneous and cutaneous etiologies. At our institution we have encountered FDG-PET scans which demonstrated a variety of cutaneous and subcutaneous lesions including stomas, hernias, rhinophyma, dose infiltrations, physiologic muscle uptake, and tophaceous gout. Additionally, malignant cutaneous and subcutaneous malignant lesions may also demonstrate substantial F-18 FDG uptake on PET scans, including lymphoma, skin metastases, and melanoma. The purpose of this atlas article is to demonstrate and review key features of various cutaneous and subcutaneous lesions, both benign and malignant, which can result in hypermetabolism on FDG-PET or PET-CT scans.

Incidental Finding of F-18 FDG Skin Uptake in a Patient With Psoriasis During the Evaluation of a Recurrent Papillary Thyroid Carcinoma

“…Many causes of increased cutaneous FDG activity have been reported, in particular melanoma or skin lymphoma, which can be indication for FDG PET. 8,9 More unusual cancers such as Merkel cell carcinoma, 10 metastases of solid tumors, 8,11,12 eccrine porocarcinoma, 13 or granulomatous slack skin 14 can present an FDG uptake. A cutaneous uptake can also be observed in benign lesions such as infectious pathologies 15 or dermatofibroma 16 or in benign conditions, such as stomas, hernias, postoperative wound healing, or dose infiltrations.…”

“…A cutaneous uptake can also be observed in benign lesions such as infectious pathologies 15 or dermatofibroma 16 or in benign conditions, such as stomas, hernias, postoperative wound healing, or dose infiltrations. 8 Therefore, a rapid physical examination and the report of the history of patients is always important before interpreting PET. (right) showing an intense uptake of a thick psoriasis plaque of the upper neck, in a 63-year-old man.…”

[ 18 F]‐Fluorodeoxy‐D‐glucose uptake in prurigo nodules induced by the membranous expression of glucose transporter

“…Positron emission tomography/computed tomography (PET/CT) is a valuable imaging technique for assessing malignant tumours; however, the aberrant uptake of [ 18 F]‐fluorodeoxy‐ d ‐glucose (FDG) is sometimes observed in benign skin lesions such as corns, seborrhoeic keratosis, viral warts, condyloma acuminatum, rhinophymas and acne vulgaris . We encountered a case of prurigo nodularis associated with abnormal uptake of FDG, and evaluated the expression of the glucose transporter in the lesions.…”

Optimal follow-up for melanoma

“…Secondly, this modality has a low ability to detect pulmonary metastases, which has been attributed to, for example, respiratory movement and scatter from other organs in basal lung fields. And, thirdly, false-positive hotspots occur due to hypermetabolism for other reasons [99]. So, verification of PET and CT findings remains necessary in patients to prevent potentially beneficial surgery for localized disease being withheld.…”