F-18 FDG PET/CT in Granulomatous Slack Skin

The utility of positron emission tomography with and without computed tomography in patients with nonmelanoma skin cancer

Combined positron emission tomography (PET) and computed tomography (CT) scans are widely used in the staging and monitoring of most malignancies. The differential for PET-positive cutaneous lesions includes primary skin cancers, infections, cutaneous metastases from distant malignancies, and benign neoplasms. In dermatology, PET/CT scans have been most widely studied in patients with melanoma and Merkel cell carcinoma. The role of PET/CT scans in the management of other cutaneous malignancies is less clear, but it has shown great promise in the management of patients with squamous cell carcinoma and cutaneous lymphoma. This review seeks to address the usefulness of PET/CT scans in nonmelanoma skin cancer and to provide guidance regarding the management of patients with incidental PET-positive nodules. Currently, there is limited experience with PET/CT scans for staging and monitoring of non-head and neck metastatic basal cell and squamous cell carcinomas, and results show limited sensitivity and specificity. We also address the evidence for management of an incidental PET-positive cutaneous nodule and recommend obtaining a biopsy specimen in patients with a known noncutaneous malignancy, a history of primary skin cancer, or a high risk of either cutaneous or noncutaneous malignancy.

Incidental finding of F-18 FDG skin uptake in a patient with psoriasis during the evaluation of a recurrent papillary thyroid carcinoma

We report the case of a patient, referred in our institution for a PET/CT for a suspected recurrence of papillary thyroid carcinoma. An intense cutaneous uptake of FDG was seen in the upper neck region. The clinical examination showed an indurate and thickened red descamative plaque evocative of psoriasis, and the patient reported a long history of psoriatic lesions of the skin, evolving for many years. This case illustrates an incidental finding which must be recognized, and not confounded with other causes of skin uptake. The FDG image is not surprising, as FDG uptake is expected in active inflammatory disease.