-Yi Cheng

Conversion from FDG-negative to -positive during follow-up in a rare case of pulmonary lymphoepithelioma-like carcinoma.

A female patient aged 75 years presented with an incidental pulmonary nodule without FDG uptake when undergoing FDG PET/CT. Without obtaining histologic diagnosis, the follow-up FDG PET/CT 2 years later demonstrated intense FDG avidity within previously FDG-negative tumor. After surgery, the pathologic diagnosis is pulmonary lymphoepithelioma-like carcinoma (LELC). LELCs are unique because of histologic similarities with undifferentiated nasopharyngeal lymphoepithelioma and with a better prognosis as compared with other lung malignancies. However, the expression of FDG uptake in LELC has never been discussed. Herein, we describe a pulmonary LELC manifesting as a slowly growing tumor displaying conversion from FDG-negative to -positive avidity.

Colon Visualization on Bone Scan: A Special and Interesting Case

Several causes of bowel visualization on bone scintigraphy have been discussed. Tc-99m MDP whole-body bone imaging was performed on a 38-year-old woman for clinical staging of breast cancer. The bone scintigraphy demonstrated no skeletal abnormality. However, extensive accumulation of radioactivity in the colon was noted. This resulted from the patient drinking her own urine, because some people believe that it is a way to improve their health. To avoid such misleading conditions, thorough history taking, including administration of traditional remedies, special habits, and the habitat of the patient, are necessary before imaging.

Tumoral calcinosis demonstrated on Tc-99m sestamibi scintigraphy.

A 61-year-old uremic male under hemodialysis underwent Tc-99m sestamibi scintigraphy due to suspicious secondary hyperparathyroidism. The images showed increased uptake in the right forearm, left shoulder, right knee and, to a lesser extent, in the left hip and the right thigh. Subsequent Tc-99m MDP bone scintigraphy and x-ray studies revealed intense extraosseous uptake and calcified masses in areas corresponding to those found in Tc-99m sestamibi scintigraphy, suggesting tumoral calcinoses. We demonstrate the rare case in which Tc-99m sestamibi was taken up by tumoral calcinoses.

The Solitary Scalp Metastasis from Pulmonary Squamous Cell Carcinoma Seen on FDG PET/CT

The solitary skin metastasis from lung cancers is an unusual event, particularly in the scalp. We report a case of 57-year-old male with a history of heavy smoking for nearly 30 years who has experienced hoarseness and easily choking while drinking for about 1 month. Simultaneously developed symptoms of left vocal cord paralysis and a scalp lesion over the right upper vertex were initially noted by an otolaryngologist. A routine chest X-ray demonstrated a nodular density at retrocardiac region of left lower lung that turned out to be a squamous cell carcinoma (SCC) histologically. However, a benign fibrotic change was reported from biopsy of the scalp lesion. An FDG PET/CT was performed for staging of the lung cancer and incidentally found an unusually high uptake of FDG in the scalp lesion. Under tentative diagnosis of malignancy, he received a repeated biopsy of the scalp lesion in reference to the FDG uptake site and confirmed as a metastatic SCC consistent with the primary lung malignancy. The patient survived 9 months after onset of symptoms. We present this rare case here and illustrate clinical usefulness of FDG uptake in allocating sites of biopsy.

Visualization of Ectopic Ureteral FDG Retention in an Incidental Case of Duplex Renal Collecting System

Ureteral duplication anomaly is usually diagnosed by ultrasound, voiding cystourethrography, radioisotope renography and sometimes excretory urogram, but there have been not many cases of F-18 FDG PET-demonstrated ureteral duplex. We describe a 68-year-old female without history of abdominal-pelvic malignancy. Under health examination, F-18 FDG PET showed extraordinarily ureteral FDG activity connecting to the upper pole of kidney. Co-registered CT scan displayed duplex renal collecting system by presenting Y-shaped ureter.

Aggressive Right Atrial Tumor with Extensive FDG-avid Metastases in a Case of Cardiac Angiosarcoma

Primary cardiac tumors are rare and only a quarter of them are malignant with the vast majority being angiosarcomas. Prognosis of cardiac angiosarcoma is very poor, with median survival of less than 1 year. Patients with complete surgical resection of tumor might have longer survival, but it is feasible only in absence of metastasis. However, metastatic cardiac angiosarcoma via hematogenous routes to the lungs, bones and liver are not unusual. Because of rarity of cardiac angiosarcoma, the literature regarding with its metastases demonstrated on FDG PET/CT is only anecdotal. Herein, we described the PETICT features of multiple extracardiac FDG-avid metastases in a case of cardiac tumor, misdiagnosed as hemangioma after initial resection but finally revised as angiosarcoma when metastasis became evident within several weeks post-operation. Also because of disseminated metastases and expected poor survival, the patient opted not further treated. Our experience with this case suggests that the regular use of FDG PET/CT may provide not only additional but essential information to facilitate a correct diagnosis of cardiac tumor and can avoid medical malpractice.

Unusual Tc-99m methylene diphosphonate uptake by clinically suspected adrenal metastases from hepatocellular carcinoma.

In a 64-year-old female patient with hepatocellular carcinoma and increasing serum alpha-fetoprotein level, a newly developed mass lesion over the right adrenal region was detected by computed tomography, whereas the same lesion also demonstrated prominent fluorodeoxyglucose uptake on the following fluorodeoxyglucose positron emission tomography/computed tomography. Then, adrenal metastasis was clinically diagnosed. Interesting, a cap-like Tc99m methylene diphosphonate uptake over the right suprarenal region of right kidney was noted on the whole body bone scan, which was not shown on the prior study in 1 year ago. In this case, bone-seeking agents unusually accumulated within the supra-renal lesion are highly associated with adrenal metastasis, which is rarely reported before, and the possible etiologies are being discussed.

FDG PET/CT Demonstrates Malignant Fibrous Histiocytoma in a Patient with Nasopharyngeal Carcinoma after Radiation Therapy

A 25-year-old young male is a victim of undifferentiated nasopharyngeal carcinoma (NPC) s/p an 8,200 cGy external radiation therapy about 5 years ago, who was referred to our positron emission tomography (PET) center for evaluating a protruding mass in his nasal cavity. 18F-fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET/CT) imaging incidentally demonstrated a hypermetabolic lesion in the right nasal cavity and right maxillary sinus, which was suggestive of tumor recurrence. However, the surgical pathology report showed a picture of moderately differentiated sarcoma characterized by bizarre tumor giant cells, abnormal mitotic figure and intermixed with inflammatory cells. The immunohistochemical stains of the tumor cells showed positive for vimentin, which was compatible with malignant fibrous histiocytoma (MHF). Since radiation therapy is a well-known risk factor of MFH, which remind us that MFH should be ruled out in a NPC patient post radiotherapy and PET/CT scan is a valuable modality in detecting a second cancer, such as MFH. Furthermore, MFH usually happen to aged subgroup at limbs and retroperitoneum, our report presented rare case of a young male with MFH involving maxillary sinus and nasal cavity.