Positron emission tomography and Paget disease: hot is not necessarily malignant

INCIDENTAL PAGET'S DISEASE DISGUISED AS BONE METASTASIS IN A PATIENT WITH ENDOMETRIUM CARCINOMA

Paget's disease is a disorder of aging bone which occurs in the setting of accelarated bone remodelling. In the presented case we discuss the difficulties in the diagnosis of Paget's disease in a 77 year old patient with coexisting endometrium carcinoma. The patient was initially diagnosed with metastatic bone disease due to endometrium adenocarcinoma when she was admitted to oncology clinic with pelvic pain. Bone scintigraphy with Tc99 and (18)F fluorodeoxyglucose positron emission tomography/CT revealed an increased uptake on the bone lesions which were reported as metastatic bone involvement. Although the (18)F-FDG uptake was much higher than the levels that would generally be anticipated in a case with Paget's disease, high levels of bone turnover markers indicated further evaluation in the differential diagnosis and the definitive diagnosis of Paget's disease was established with the pathological evaluation of bone biopsy.

Response monitoring to bisphosphonate therapy in monostotic paget disease using (18)F-FDG PET/CT

Paget disease is a benign bone disorder characterized by abnormal bone absorption and mineralization, resulting in bone deformity and fragility. Currently, bisphosphonates form the cornerstone of treatment for Paget disease. We report the case of a 67-year-old man with monostotic Paget disease, where F-FDG PET/CT was used for assessment of response to bisphosphonate therapy.

Paget sarcoma of the pelvic bone with widespread metastatic disease on radiography, CT, MRI, and 18F-FDG PET/CT with pathologic correlation

We report a case of Paget sarcoma of the left superior pubic ramus and disseminated metastatic disease in a 70-year-old man. Paget disease of the left hemipelvis with malignant degeneration in the region of the left superior pubic ramus was initially diagnosed on radiographs. Subsequent CT, MRI, PET/CT imaging, and CT-guided biopsy confirmed the diagnosis and showed extensive left-sided pelvic and abdominal lymphadenopathy with widespread metastatic disease to liver, spleen, and lungs.

[Positron emission tomography-computed tomography in tumors of the locomotor apparatus]

Positron emission tomography/computed tomography (PET/CT) is a hybrid imaging technique that combines the anatomic information from CT with the metabolic information acquired from PET after the administration of specific radiotracers, the most commonly used of which is F18-fluorodeoxyglucose (FDG). In oncology, this technique is based on the increased uptake of FDG by malignant lesions. In the locomotor apparatus, some uptake by bones and soft tissues is physiological or benign and this uptake must be differentiated from uptake by malignancies, whether primary or secondary. The most important limitations are active inflammatory or infectious processes, which are positive on PET images, and malignant lesions that are smaller than 1cm, cystic, necrotic, or low-grade, which are negative on PET images. PET/CT in the locomotor apparatus is especially useful for the detection of metastases from the most common tumors. It is also used for staging and monitoring the response to treatment of some hematological tumors like lymphoma, where it is fundamental to determine whether the bone marrow has been infiltrated, or myeloma. Lastly, although it is not yet an established indication, PET/CT is being increasingly used to study sarcomas, because it can provide additional information that can be useful for the characterization and grading of tumors, for guiding biopsies, for staging and re-staging, and for evaluating the response to neoadjuvant therapy as well as for evaluating new drugs in clinical trials.

Paget disease of the humerus mimicking metastatic disease in a patient with metastatic malignant mesothelioma on whole body F-18 FDG PET/CT

A 71-year-old man with newly diagnosed malignant mesothelioma was referred for an F-18 FDG PET/CT study to evaluate the extent of disease. PET showed mild FDG uptake in the right chest, corresponding to a lobulated, mass-like right pleural effusion versus thickening involving the entire right pleural space, and some mediastinal involvement, on the accompanying CT scan. In addition, marked FDG uptake was seen in the proximal left humerus, suspicious for an osseous metastasis. The corresponding CT scan findings of cortical thickening and a "Swiss cheese" appearance were most consistent with Paget disease. The intense FDG uptake in an osseous lesion on FDG-PET in our case reminds us of the variable nature of FDG uptake in Paget disease, the possibility of false-positive findings on FDG-PET in patients with cancer, and the usefulness of the fusion techniques in the evaluation of skeletal lesions, with the potential for discriminating between benign Paget disease and other pathologic bone findings.

Bilateral Paget disease of the calcaneus diagnosed by conventional bone scintigraphy

An 85-year-old woman who had an invasive ductal carcinoma of the breast and elevated alkaline phosphatases (420 U/L) was referred for Tc-99m MDP bone scintigraphy for initial evaluation of skeletal metastases. Bone symptoms were limited to chronic pain in both knees. A bone scan revealed pagetoid findings in both calcanei. Feet and toes on plain x-rays of the calcaneus were unremarkable. Findings were stable in the 2-year follow up, excluding other potential diagnosis as extensive metastases or stress fractures.

PET/CT imaging of metastatic deposit in vertebral Paget's disease

Metastatic involvement in monostotic Paget's disease is an event of uncommon occurrence. An osseous metastasis, clinically and radiologically difficult to differentiate from sarcomatous degeneration, is often unexpectedly discovered during evaluation for malignant transformation of Paget's disease. The authors present a case of recurrent nonsmall cell lung carcinoma with PET/CT imaging instrumental in the diagnostic biopsy of a metastatic deposit in a pagetoid lumbar vertebra.

Positive Tc-99m-MIBI scan in a patient with confirmed Paget's disease of bone

A 46-year-old man was referred to our department for a Tc-99m MDP bone scan after he was admitted to our hospital with diffuse bone pain and the subsequent finding of multiple mixed type (lytic-blastic) lesions on routine x-rays. The Tc-99m MDP scan was highly suspicious for malignancy and, therefore, a Tc-99m MIBI scan was performed, which also revealed abnormal uptake in all regions with increased osteoblastic activity. Clinical chemistry and further workup revealed a highly elevated serum alkaline phosphatase and increased excretion of hydroxyproline in the urine. The presumed diagnosis of Paget's disease of the bone was further confirmed by biopsy.