Primary tumor size and the mapped sentinel node: Nuclear medicine in the management of early stage breast carcinoma

A treatment option for early stage breast cancer is nodal evaluation by axillary lymph node dissection (ALND). An alternative to ALND is sentinel lymph node (SLN) biopsy employing radionuclide SLN mapping. This study was designed to investigate the relationship between malignancy spread to the SLN and primary tumor size by reviewing the clinical profile of 20 female breast cancer patients who underwent radionuclide SLN mapping procedure, sentinel lymph node and primary tumor biopsy, as well as axillary lymph node dissection. The accuracy of radionuclide mapping in the identifying the sentinel node and determining the status of the axillary lymph nodes was reviewed. Among the mapped sentinel nodes, 15% were positive for metastatic lymphadenopathy and 85% without malignant spread. The malignant sentinel nodes had a mean size of 5.5 ± 0.87 cm and the negative sentinel nodes had a mean size of 2.95 ±2.2 cm. The SLN identified by radionuclide mapping truly represented the status of the rest of the axillary nodes for the presence or absence of metastatic lymphadenopathy. Primary tumor size is a prognostic factor for cancer spread to the sentinel node. However, the combination of primary tumor histology and tumor size may prove to be a stronger prognostic indicator malignancy spread to the sentinel lymph node.

Silent parathyroid adenoma mistakenly interpreted on FDG-PET as thyroid cancer metastasis in a patient with elevated thyroglobulin and negative I-131 whole body scan and removed by radioguided minimally invasive surgery.

Detection of recurrent and metastatic thyroid cancer remains a considerable challenge in patients presenting with rising thyroglobulin levels but with negative I-131 whole body scintigraphy. Such is the case in this patient with follicular thyroid cancer in whom subsequent FDG PET scanning showed a solitary hypermetabolic cervical lesion. With definitive management and multidisciplinary approach in mind, radioguided surgical excision came into play through the use of Tc-99m sestamibi, leading to successful removal of the lesion. Histopathology, however, revealed a parathyroid adenoma. This highlights the importance of considering differential diagnoses in apparent cases of recurrence to avoid potential pitfalls.