Herpes Zoster mimicking recurrence of lymphoma on PET/CT

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.

Musculoskeletal Pitfalls on Fluorodeoxyglucose F 18 PET-Computed Tomography: Pictorial Review

A wide range of musculoskeletal processes can demonstrate increased uptake on PET-computed tomography (CT) with fluorodeoxyglucose (FDG) F 18, including reactive, benign neoplastic, inflammatory, traumatic, posttreatment, and arthritic conditions that may mimic malignancy. In addition, physiologic causes of increased FDG uptake such as asymmetric muscle use and presence of brown fat can lead to increased FDG uptake and potential false-positive results. This article presents various case examples of non-malignant musculoskeletal hypermetabolism on 18F-FDG PET-CT and describes useful tools to avoid the potential pitfall of misinterpreting these as malignancy.

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.

Blastic Plasmacytoid Dendritic Cell Neoplasm Evaluated by FDG PET/CT

Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is a rare and aggressive hematological malignancy. A 34-year-old man with a biopsy-proven BPDCN underwent FDG PET/CT for staging. FDG PET/CT revealed multiple mild FDG-avid cutaneous lesions on the chest and back, involvement of left inguinal lymph node, and a markedly increased FDG-avid subcutaneous mass in the left lower leg.

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.

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.

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

This is a 66-year-old female patient being treated for diffuse large B-cell lymphoma. She reported to her physician in late January 2012 with a left flank pruritic painful rash. She was diagnosed with herpes zoster and treated with antiviral medication. Her chemotherapy regimen was delayed due to the zoster infection. In March 2012, the patient underwent a PET/CT as a lymphoma surveillance scan prior to reinstituting the chemotherapy treatment. As an incidental finding, the PET showed increased metabolic activity in a dermatomal distribution along the left flank, which corresponded to the patient's zoster infection.

Active Shingles Infection as Detected on (18)F-FDG PET/CT

We present the case of a 56-year-old male with a history of recurrent follicular lymphoma undergoing chemotherapy with multiple (18)F-FDG PET-CT studies at an outside facility. He developed a painful erythematous, pruritic rash in the left back requiring a visit to the emergency room. He was diagnosed and treated for Varicella zoster infection. He then presented to our imaging center 2 months later for a follow up (18)F-FDG PET/CT study. Imaging demonstrated a cutaneous band of increased metabolic activity in the upper back following a dermatomal distribution. This was confirmed to be in the same area as the treated Varicella zoster eruption. A subsequent follow up (18)F-FDG PET-CT scan 4 months later to confirm tumor resolution demonstrated the abnormal band of uptake in the back had resolved. This case illustrates the significance of being aware of this entity and to distinguish it from metastasis, especially in patients with a known history of malignancy.

A rare case of pemphigus vegetans mimicking malignancy on F-18 FDG PET/CT

A 42-year-old man with a history of chronic smoking and alcoholism was suspected to harbor a malignancy involving the perioral region and the scalp. He underwent an F-18 FDG PET/CT scan which revealed abnormal F-18 FDG accumulation in the oral mucosa and lips, extending to the nose, scalp, and bilateral cervical lymph nodes. Further work-up ultimately revealed the lesions to be secondary to pemphigus vegetans. Pemphigus vegetans is a rare variant of pemphigus vulgaris, an autoimmune bullous cutaneous disorder and involves mainly the flexural regions of the body. Unlike pemphigus vulgaris, lesions of pemphigus vegetans present as heaped up, eroded, and ulcerative plaques in the intertriginous regions of the body. Occasional lesions may be present on scalp and elsewhere in the Hallopeau variant of the disease. The use of F-18 FDG PET in the field of oncology is rapidly evolving; however, it is not tumor specific. The integration of CT into PET has increased the specificity of this modality. Nevertheless, there are many physiologic and benign conditions that may result in high accumulation of FDG, and may mimic malignancy. Familiarity with F-18 FDG-avid nonmalignant lesions may extend the use of F-18 FDG PET imaging beyond the field of oncology. To the best of our knowledge, this is the first description of PET/CT findings in pemphigus vegetans.

Acute Varicella Infection Mimics Recurrent Hodgkin's Disease on F-18 FDG PET/CT

We report a case where acute varicella infection, chickenpox, mimics the findings of recurrent Hodgkin disease on F-18 FDG PET/CT. A 28-year-old man with a history of Hodgkin disease in remission had fatigue, pyrexia, and a raised ESR. His F-18 FDG PET/CT, performed to exclude lymphoma recurrence, demonstrated FDG-avid lymphadenopathy and increased FDG uptake in his spleen. A day later he developed the generalized rash of acute varicella infection. This was managed with valacyclovir. Repeat F-18 FDG PET/CT done 1 month later showed no evidence of FDG-avid disease. In this patient the stimulation of an immune response by the acute viral infection mimics recurrent lymphoma.