An unknown primary tumor (UPT) is defined as a biopsy-proven malignancy whose anatomic origin remains unidentified after diagnostic evaluation. The estimated incidence of unknown primary tumors is 2 %-7 % of all malignancies. In 15-25 % of cases, the primary site cannot be identified even on postmortem examination. The management of these patients remains a clinical challenge. The aim of this study was to determine the role of 18FDG-PET CT in evaluation of primary tumor and its influence on therapeutic management. Fifty patients with histologically-proven metastases of UPT were included. For all patients, the conventional diagnostic work-up was unsuccessful in localizing the primary site. Whole-body PET/CT images were obtained approximately 60 min after intravenous injection of 350-425 MBq of (18) F-FDG. PET/(CT) depicted histologically verified primary tumors in 21of 46 patients (P>.05), achieving detection rates of approx. 61 % in patients presenting with cervical lymph node metastases from unknown primary tumors, and 40 % in those with extra cervical disease presentation. A positive predictive value of 72 % to 92 % was seen for all patients, depending on category of clinical presentation. In this study, PET/CT detection of additional metastases in 14.2 % (3 cases out of 21 true positives) influenced change in management plan. Considering recent studies and the results of this study, whole body FDG-PET/CT has to be considered a useful tool in evaluating metastases from an UPT, allowing an identification of primary tumors in 42 %, and modifying the stage of the disease and oncological treatment in about 50 % of cases. These results suggest the use of PET/CT with FDG in an early phase of the diagnostic evaluation to optimize the management of these patients.

Sentinel lymph node (SLN) biopsy has become the standard of care in axillary staging of breast cancer patients who are clinically node negative as it reduces the morbidity of axillary nodal dissection. SLN biopsy using blue dye and radioisotopes have high identification rates but its limitations include anaphylaxis, disposal of radioactive waste, and potential second surgery in up to 35% of patients who show nodal metastases on SLN biopsy. Contrast-enhanced ultrasound (CEUS) has the potential for SLNs to be identified without the aforementioned risks. CEUS involves the administration of intravenous contrast agents containing microbubbles of perfluorocarbon or nitrogen gas. The bubbles greatly affect ultrasound backscatter and increase vascular contrast in a similar manner to intravenous contrast agents used in CT and MRI. It is safe and easily performed with no requirement for ionizing radiation and no risk of nephrotoxicity. Microbubbles are taken up by lymph nodes when injected directly into tissues, including sub-areolar injection in the breast cancer patient. This method may prove valuable in patients with ductal carcinoma in situ, where operative SLN biopsy remains controversial, and in women undergoing prophylactic mastectomies for high risk. This technique may also have a role after neoadjuvant chemotherapy where frequently there is fibrosis in the treated SLNs.

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Ameloblastoma is a common benign, locally aggressive odontogenic neoplasm that usually occurs in the vicinity of the mandibular molars or ramus. Uncontrolled, ameloblastoma may cause significant morbidity and occasionally death. The majority of ameloblastomas are multicystic, which are more difficult to eradicate than the unicystic and peripheral varieties. Although surgery is the mainstay of treatment, the extent of resection is controversial. The challenge in managing ameloblastoma is in achieving complete excision such that chances of recurrence is minimal and reconstruction of the defect when the tumour is large.