Increased FDG uptake along dermatome on PET in a patient with herpes zoster

Unusual Presentation of Herpes Zoster Infection Mimicking Soft Tissue Metastases of Breast Cancer on 18F-FDG PET/CT Imaging

ABSTRACT

Herpes zoster infection caused by reactivation of dormant varicella zoster virus results in painful vesicular rash in corresponding dermatome. We report a case of a 56-year-old woman with breast cancer who was referred to PET/CT scan for adjuvant chemotherapy response assessment. Her scan showed multiple FDG-avid skin lesions. Blinded to the patient's clinical information, these skin lesions initially looked suspicious for soft tissue metastases. However, the patient history revealed that she had been experiencing herpes zoster infection during the scan, and these lesions with FDG uptake were eventually confirmed to be caused by herpes zoster infection by physical examination.

Active Herpes Zoster Mimicking Worsening of Axillary Lymph Node Metastases of Breast Cancer after Chemotherapy on 18F-Fluorodeoxyglucose Positron-Emission Tomography/Computed Tomography

A woman in her 60s presented to our hospital with a left breast mass that was diagnosed as breast cancer. 18F-Fluorodeoxyglucose positron-emission tomography/computed tomography (18F-FDG PET/CT) revealed intense, hot uptake in the cancerous mass and left axillary lymph node metastasis. After chemotherapy, another PET/CT scan was performed. Although the mass and left axillary lymph nodes shrank and FDG uptake decreased, enlarged lymph nodes with high FDG uptake appeared in the right axilla. The patient had a painful vesicular eruption on the front to the back of the right upper hemithorax, which was diagnosed as active herpes zoster. Active herpes zoster mimics a worsening axillary lymph node metastasis on the PET/CT scan.

FDG-Avid Keloid on PET/CT Imaging

Keloid is a benign fibroproliferative growths resulting from an overexuberant healing response. A 51-year-old man with a 20-year history of keloid formation presented with a 1-year history of unexplained progressive weakness of both lower limbs. He was clinically suspected of having paraneoplastic neurologic syndrome. FDG PET/CT was performed to exclude underlying malignancy. FDG PET/CT revealed a giant FDG-avid keloid in the anterior chest wall without any other abnormal FDG uptake in the body. We emphasize that a benign FDG-avid keloid should be considered in the differential diagnosis of FDG-avid cutaneous lesions on PET/CT.

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.

Zosteriform Secondary Cutaneous Diffuse Large B-Cell Lymphoma on FDG PET/CT

We present a case of a woman who had erythematous papules on the abdomen accompanied with numbness and local heat sensation. She had received chemotherapy for advanced follicular lymphoma. F-FDG PET/CT demonstrated band-like hypermetabolic lesions seemingly involving dermatomes of lower abdominal wall, which was confirmed as secondary cutaneous diffuse large B-cell lymphoma via skin biopsy.

Assessing Cutaneous Psoriasis Activity Using FDG-PET: Nonattenuation Corrected Versus Attenuation Corrected PET Images

Psoriasis is a chronic inflammatory skin condition characterized by well-circumscribed erythematous plaques with thick silvery scale. Infiltration of inflammatory cells such as lymphocytes, neutrophils, and macrophages and epidermal cell proliferation within psoriatic lesions may result in selective FDG accumulation. We present a 55-year-old patient with a 30-year history of psoriasis. Nonattenuation corrected PET/CT images demonstrated significant cutaneous FDG uptake corresponding to clinically apparent psoriatic lesions. However, in attenuation corrected (AC) FDG-PET images, the signal was substantially diminished and minimally detectable. Nonattenuation corrected FDG-PET images may be useful and preferable to AC images in assessing skin inflammation in psoriasis.

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.

Active herpes zoster infection with cutaneous manifestation and adenopathy on FDG PET/CT

We report a patient with history of Hodgkin lymphoma. Six months after treatment, 2-deoxy-2-[18F]fluoro-d-glucose positron emission tomography and/or computed tomography ([18F] FDG PET/CT) scan showed abnormal uptake in right axillary lymph nodes concerning for recurrence. In addition, PET/CT showed a new hypermetabolic skin lesion overlying the right scapula. Clinical evaluation was consistent with shingles, and the patient was treated with valacyclovir. Subsequent PET/CT scan was normal with no evidence of lymphoma. Although there have been reported cases of abnormal FDG in nodes or in skin due to herpes zoster, our case is unique in the literature in that the PET/CT demonstrates abnormalities involving both the skin and associated lymph nodes. The possibility of false positive uptake, not because of recurrent malignancy, must always be considered when abnormal FDG uptake is noted in the follow-up of oncology patients. Careful review of the scan and correlation with clinical findings can avoid false positive interpretation and facilitate patient management.

Extensive invasive extramammary Paget disease evaluated by F-18 FDG PET/CT: a case report

Extramammary Paget disease (EMPD) is a rare cutaneous, intraepithelial adenocarcinoma. Because of its rarity, little is known about the value of fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) in evaluating this disease. Our case report aims to increase current knowledge of FDG PET/CT in EMPD as a noninvasive imaging tool for assessing the extension of the disease and detecting distant metastases.We reported a 64-year-old Chinese man who presented with a slowly progressive, ill-margined erythematous lesion with a crusted, eroded, and scaly surface involving multiple sites of penis, scrotum, left pelvic wall, hip, groin, and thigh for >4 years, which became extensive in the past 1 year. He was referred for an FDG PET/CT examination to further evaluate the lesions. A following skin biopsy was performed to obtain a definitive histological diagnosis.FDG PET/CT imaging revealed mild FDG uptake at the extensive cutaneous lesion with subcutaneous invasion, involvement of lymph nodes, and multiple intense FDG-avid of skeletal metastases. According to the appearance of FDG PET/CT, a provisional diagnosis of advanced cutaneous malignancy was made. Histopathology findings indicated characteristic of EMPD. The patient was treated with radiation therapy and died from complications 2 months after the last dose of radiotherapy.Our case highlighted that a whole-body FDG PET/CT should be incorporated into the diagnostic algorithm of EMPD to give a comprehensive assessment of this disease.