[18F]-FDG uptake in soft tissue dermatome prior to herpes zoster eruption: an unusual pitfall

Herpes zoster reactivation during head and neck cancer therapy: interpreting post-treatment positron emission tomography/CT imaging

The risk of herpes zoster reactivation in patients undergoing cancer treatment is significant, though this phenomenon has rarely been reported in the head and neck squamous cell carcinoma (HNSCC) population. We aim to report the potential for infection to lead to false-positive findings on positron emission tomography/CT in these patients. This case highlights the potential for herpes zoster reactivation to result in false-positive findings on post-treatment imaging following chemoradiation for HNSCC. It is therefore imperative for providers to be aware of this when evaluating patients during and after treatment for HNSCC.

Active Herpes Zoster Infection Involving Lumbosacral Dermatome, an Unusual Site of Manifestation and Incidental Finding in Fluorine-18 Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography Scan

Herpes zoster virus reactivation in the lumbosacral dermatomal distribution is an unusual site of manifestation and atypical in presentation than its usual sites in thoracolumbar (D3-L2) and facial (V1) dermatomes. Here, we are reporting a patient of marginal zone lymphoma who on fluorine-18 fluorodeoxyglucose (FDG) positron emission tomography/computed tomography scan performed for chemotherapy response evaluation showed hypermetabolic cutaneous and subcutaneous lesions in the right vulva and posteromedial aspect of the right thigh along with ipsilateral pelvic lymph nodes involvement as an incidental finding. Subsequently, FDG active lesions were considered to be as herpes zoster virus reactivation rather than the recurrence of lymphoma and treated with antiviral drug.

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.

Herpes Zoster Mimicking Breast Cancer With Axillary Lymph Node Metastasis on PET/CT

Herpes zoster is a reactivated varicella-zoster virus infection and demonstrates typical dermatomal distribution. We herein describe a case of a 41-year-old woman with a history of ovarian cancer. Intense hot uptake in the left breast and enlarged ipsilateral axillary lymph nodes were noted on ¹⁸F-FDG PET/CT for adjuvant chemotherapy response evaluation. Blinded to the patient's clinical information, these lesions were interpreted as incidental breast cancer with axillary nodal metastasis. However, clinically she presented with vesicles along the T4 dermatome and palpable enlarged nodes in the left axilla. On 3-month follow-up PET/CT after antiviral treatment, these intense hot uptake areas were no longer visualized.

Increased FDG uptake in scrotal steatocystoma multiplex with calcification

Steatocystoma multiplex is a rare, benign, sporadic or familial disorder. Steatocystoma multiplex with extensive calcification is extremely rare. A 57-year-old man presented fever and cough with expectoration for 3 weeks. Chest CT showed bilateral pleural effusion. FDG PET/CT showed diffuse FDG uptake of the bone marrow and multiple hypermetabolic calcified nodules in the scrotum with SUVmax of 7.6. Blood culture revealed septicemia. Skin biopsy of the scrotal nodules revealed steatocystoma multiplex with calcification. Histopathologically, there were rich multinucleated giant cells and lymphocytes in the cyst wall of the steatocystoma, which may contribute to the increased FDG uptake.

Cutaneous and subcutaneous imaging on FDG-PET: benign and malignant findings

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.