A 43-year-old woman was referred to our hospital with history of left
breast multifocal ductal carcinoma in situ for which she underwent bilateral
mastectomy and reconstruction in 2006. Her family history was significant for
breast cancer: Her sister was diagnosed at age 38, maternal aunt at age 36 and
maternal cousin at age 25. All died from metastatic disease. She was positive
for BRCA2 mutation, at which time she opted for left mastectomy and
prophylactic right mastectomy. She now presents with palpable mass in the left
axilla and underwent an FNA of the mass, which showed moderate cellularity
composed of polymorphous population of lymphocytes, predominately small
lymphocytes, with no evidence of malignant cells. She later underwent an
ultrasound of the left axilla that showed a 2.7 cm × 2.2 cm × 0.9
cm lobulated mass representing lymph node with an echogenic fatty hilum.
A core biopsy of the left axillary lymph node showed adenocarcinoma with
ER 90% positive, PR 50% positive, HER2-neu2 positive by immunohistochemistry
and negative by fluorescent in situ hybridization and E-cadherin positive. A
staging PET/CT showed a hypermetabolic 16 mm × 7 mm left axillary lymph
node with maximal SUV of 2.7 and superiorly, there was a smaller lymph node
measuring up to 8 mm × 5 mm with maximal SUV up to 1.1. There were no suspicious
lesions in the breast or contralateral axilla, or systemically.
She will undergo axillary lymph node dissection, systemic chemotherapy
and possible radiation.
FDG-PET imaging has 88% sensitivity and 80% specificity for primary
breast lesion, 61% sensitivity and 80% specificity for axillary metastases, and
93% sensitivity and 79% specificity for metastatic disease. Sensitivity and
specificity is further improved with simultaneous CT acquisition and image
fusion of PET and CT images.
During the past few years, with improvement of spatial resolution of
PET, we have been able to achieve a system resolution of 5 mm to 6 mm under
optimal clinical conditions. However, PET is still limited by small size of the
lesion and in general the sensitivity to detect malignant lesions decreases
with lesions <1 cm in breast tissue and axillary metastasis. Sentinel node
sampling is shown to be approximately 20% more sensitive in detection of
regional lymph node metastases from breast carcinoma.
However, it is important to note that in the appropriate clinical
setting, the presence of metabolic activity in the subcentimeter lymph nodes
should be considered suspicious for metastatic disease, unless proven
|Figure 1: Axial PET/CT image demonstrates hypermetabolic
activity corresponding to the biopsy-proven recurrent breast carcinoma in the
left axilla. Upper left image is axial CT scan, upper right image is
corresponding PET image, lower left image is fusion image containing PET images
displayed on a color scale and CT images displayed on a gray scale. Lower right
image is maximum intensity project (MIP) image of whole body PET
|Figure 2: Axial PET/CT image slightly craniad to Figure I
demonstrates hypermetabolic activity associated with subcentimeter left
axillary lymph node. Display convention is the same as Figure 1.
Courtesy of M Ghesani
In this patient, for example, it is very likely that the smaller
subcentimeter lymph node with associated metabolic activity is involved with
metastatic disease even though it does not meet the standard CT criteria for
metastatic disease. We will soon have histopathology correlation once the
patient undergoes axillary lymph node dissection.
There is ongoing research with newer techniques to improve detection and
render better staging of breast malignancy such as newer high-resolution,
high-sensitivity positron emission mammography (PEM) with either a combining
dedicated CT or dynamic contrast-enhanced MRI.
The above case illustrates the importance and significance of FDG uptake
in the subcentimeter lymph nodes for positive disease while the absence of FDG
uptake does not rule out disease due to resolution limitation of PET/CT.
For more information:
- Frangioni JV. J Clin Oncol. 2008;26:4012-4021
- Rosen EL. Radiographics. 2007;27:S215-S229.
- Weber WA. J Clin Oncol. 2006;24:3282-3292.
- Vamsee Torri, MD, is a Fellow in Hematology/Oncology at St.
Lukes-Roosevelt Hospital Center.
- Sharon Rosenbaum Smith, MD, is Attending Breast Surgeon at St.
Lukes-Roosevelt Hospital Center.
- Munir Ghesani, MD, is Associate Clinical Professor of Radiology at
Columbia University College of Physicians and Surgeons and Attending
Radiologist at St.Lukes-Roosevelt Medical Center.