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A 73-year-old man suffering from Cowden syndrome with gastrointestinal polyposis was referred for an 18F-FDG PET/CT after a routine gastroscopic biopsy revealed a poorly differentiated adenocarcinoma. The 18F-FDG PET/CT identified 2 foci of FDG-avid gastric adenocarcinoma on the background of extens

A 66-year-old woman with long-standing multiple sclerosis presented with a several month history of diarrhea and weight loss. F-18 FDG PET/CT imaging revealed breast, rectal, and urinary bladder masses which were biopsied to reveal 3 different synchronous primary malignancies. PET/CT is able to detect a variety of synchronous malignancies; however, the situation of detecting 3 different synchronous primaries is extremely rare, and this case highlights the importance of paying close attention to anatomic areas that are difficult to evaluate on PET/CT, even after successfully identifying one or several FDG-avid primary malignancies.

About one-third of patients with Crohn disease develop intraabdominal fistulas, and of these, cholecystocolic fistulas are among the rarest. F-18 FDG PET/CT can detect a vast variety of fistulas, although most are discovered incidentally. We present a very unusual case of a 79-year-old woman referred for an F-18 FDG PET/CT for evaluation of a solitary pulmonary nodule. A colon mass was detected incidentally that appeared to directly invade the gallbladder; however, histologic evaluation after surgery revealed a colon adenocarcinoma, with an adjacent cholecystocolic fistula arising from a transmural fissure ulcer in a nonneoplastic colon segment consistent with clinically silent Crohn disease.

Xerostomia is a significant morbidity of radiation treatment in the management of head and neck cancers. To preserve salivary function, a surgical technique has been developed that involves the transfer of one submandibular gland to the ipsilateral submental space, where it can be shielded during radiation therapy. F-18 FDG PET/CT imaging characteristics of recently or remotely transferred submandibular glands have not been previously described in the literature. We report 2 cases of patients with surgically transferred submandibular glands, which highlight a potential pitfall in the interpretation of PET/CT of the head and neck region in oncologic patients.

Malignant extrarenal rhabdoid tumor (ERRT) is a very rare type of soft-tissue sarcoma with a reported incidence of 0.3% of all soft-tissue sarcomas. Only 7 cases of spinal malignant ERRT have been reported in the literature, and to our knowledge, F-18 FDG PET/CT imaging for staging and evaluation of response to therapy for these tumors has not been previously described. This is a case of an 8-month-old boy with malignant ERRT of the spine, who was staged with F-18 FDG PET/CT, and had his tumor burden assessed with PET/CT after chemotherapy, which altered the subsequent chemotherapy regimen.

A 30-year-old woman was referred for an F-18 fluorodeoxyglucose (FDG) PET/CT to rule out lymphoma, and was found to have an incidental FDG-avid right breast nodule that grew significantly in size and FDG uptake on a subsequent scan, raising suspicion of a growing breast malignancy. Histologic evaluation showed a complex fibroadenoma with adenosis and surrounding ductal hyperplasia. Although variable F-18 FDG uptake in fibroadenomas has been described, a distinction between simple and complex fibroadenomas has not been made in the PET literature, even though complex fibroadenomas have a higher propensity to develop into malignancies. This case shows that a rapidly growing complex fibroadenoma can mimic a breast malignancy on serial F-18 FDG PET/CT scans, showing significant increase in both size and FDG-avidity on follow-up studies.

Angiomatoid fibrous histiocytoma is a very rare tumor that accounts for 0.3% of all soft-tissue tumors, and occurs predominantly in the extremities of adolescents and young adults. It has been classified by the World Health Organization as a tumor of uncertain differentiation with intermediate malignant potential, although recent evidence suggests a myoid or myofibroblastic cell origin. Most examples behave in an indolent manner with a regional recurrence rate of 15% and a rate of metastasis of 1%. We present a 29-year-old woman who was referred for an F-18 FDG PET/CT to evaluate a left shoulder mass. She had multiple local FDG-avid lymph nodes, and initial biopsy was suggestive of epithelioid sarcoma. She was treated with chemotherapy, but a post-therapy PET/CT showed minimal response and radical surgical excision was performed. The histopathology and immunohistochemistry was consistent with angiomatoid fibrous histiocytoma. This case highlights a potential new utility for F-18 FDG PET/CT in the staging and evaluation of response to therapy for this very rare soft-tissue tumor.

A 26-year-old man with a prior history of acute leukemia that was treated with a stem cell transplant (SCT) was referred for an F-18 FDG PET/CT to assess suspicious new gastric mucosal lesions. The lesions were FDG-avid and were histologically proven to be acute lymphoblastic leukemia (ALL). Extramedullary relapse of ALL after SCT is very rare, with only 60 cases reported in the literature, and the role of F-18 FDG PET/CT in monitoring for ALL relapse following SCT has not been previously investigated. This rare case report highlights the use of F-18 FDG PET/CT in staging gastric relapse of ALL following SCT.

A previously healthy 27-year-old woman presented with a thyroid goiter, symptoms of thyrotoxicosis, and mild respiratory obstruction. The serum thyroid stimulating hormone (TSH) was suppressed, serum T4 was elevated, and 24-hour radioiodine uptake was elevated at 59%. Thyroid scintigraphy showed intense uptake in an enlarged gland, with a cold nodule on the right, and a large isolated mass in the mediastinum, with very mild uptake. Total thyroidectomy and excision of the mediastinal mass revealed multiple pathologies: Graves disease in the thyroid gland with an incidental papillary thyroid carcinoma, and a benign sequestered intrathoracic multinodular goiter. Thyroid carcinoma can develop in a gland affected by Graves disease, however, the presence of concomitant sequestered intrathoracic thyroid tissue unaffected by Graves disease is highly unusual and has not been previously described. We present the scintigraphic findings, and several theories that could help explain these findings.

Gastric neuroendocrine carcinomas (NEC) are very rare, aggressive tumors of the stomach that are distinct from the more benign neuroendocrine tumors, sometimes referred to as "gastric carcinoids." We present 3 cases of gastric NEC representing various histological subtypes that were successfully staged and followed with F-FDG PET/CT, impacting therapeutic management in each case.

A 36-year-old woman presented with a 5-month history of a growing left thigh mass, causing difficulty walking. Biopsy revealed a malignant epithelioid hemangioendothelioma (EHE), and the patient was referred for a staging F-18 FDG PET/CT that showed intense FDG uptake in the thigh mass, but no FDG-avid local lymph nodes or distant metastases. A few reports have noted the usefulness of F-18 FDG PET/CT imaging in the staging of EHEs in the lung, liver, and bone marrow. This rare study highlights the usefulness of F-18 FDG PET/CT in the staging of malignant EHE of the soft tissues of the extremities.

We present a case of a woman with ulcerative colitis who was referred for an F-18 FDG PET/CT after a suspicious colonoscopy and biopsy. PET/CT showed multiple elongated foci of intense FDG uptake in the colon, a pattern commonly reported with inflammatory bowel disease; however, the possibility of lymphoma was raised. Reevaluation of the biopsies with immunohistochemistry and molecular studies revealed a peripheral T-cell lymphoma and the patient was treated with a total colectomy. In this case, F-18 FDG PET/CT was very useful in determining the extent of the disease. This case also highlights a potential pitfall whereby the tubular and multifocal appearance of this lymphoma subtype can mimic the appearance of bowel involved by inflammatory bowel disease especially on novel techniques such as PET/CT enterography and PET/CT colonography.

This is a case of a 52-year-old woman who underwent a hyster-ectomy to treat a large uterine perivascular epithelioid cell tumor. She wasfollowed with serial F-18 FDG PET/CT scans due to positive surgicalmargins and vascular invasion on pathology. Initial surveillance PET/CTperformed 6 months post surgery was negative; however, a second surveil-lance PET/CT performed 12 months post surgery showed an intenselyFDG-avid recurrence in the pelvic surgical site. The patient received localradiotherapy, 2 cycles of taxol and carboplatin, and was placed on imatinibmesylate (Gleevec). A final PET/CT performed 6 months after initiation oftherapy showed rapidly disseminating metastatic disease and the patient died1 month later. This rare report highlights a potentially new utility of F-18FDG PET/CT for surveillance of recurrence of a malignant uterine perivas-cular epithelioid cell tumor, as well as for evaluation of response to therapy. Key Words: malignant perivascular epithelioid cell tumor, PEComa,uterus tumors, FDG, PET/CT(

This report of an 82-year-old man who presented with a 3-week history of an enlarging left axillary mass and mild fevers, highlights the usefulness of both gallium-67 and F-18 FDG PET/CT imaging in the staging of histiocytic sarcoma. While PET/CT was superior in determining the extent of the disease, gallium can be used to help stage the disease in centers where PET/CT is not available.