Management of Incidental Breast Lesions Detected at Nuclear Medicine Examinations

Diagnostic Characteristics and Clinical Relevance of Incidental Hypermetabolic Breast Lesions Detected on 18F-FDG PET-CT: A Retrospective Evaluation

RATIONALE AND OBJECTIVES

The study aimed to evaluate demographic and radiological characteristics of breast incidentalomas found on 18-fluorodeoxyglucose Positron Emission Tomography-Computed Tomography (18F-FDG PET-CT) performed for extramammary indications.

MATERIALS AND METHODS

A total of 12633 18F-FDG PET-CT scans performed between January 1, 2018 and January 1, 2024, were retrospectively reviewed. Breast incidentalomas that had undergone breast imaging, tissue diagnosis, or at least 2-year radiological follow-up were included. Demographic data and lesion size were recorded. Maximum and average standardized uptake values (SUVmax-SUVavg) and SUV corrected for lean body mass (SUL) were calculated using region of interest (ROI).

RESULTS

The inclusion criteria were met in 101 lesions (81 benign and 20 malignant). The most common benign lesion was fibroadenoma (n = 21), followed by stable lesions during follow-up (n = 18) and benign breast parenchyma (n = 11). The most common malignant lesion was invasive ductal carcinoma (n = 11). The diagnostic characteristics of SUVmax≥ 3, SULmax≥ 2, SUVavg≥ 0.735, SULavg≥ 0.48, and BI-RADS≥ 4 were 75%, 70%, 75%, 70% and 100% for sensitivity, 69%, 69%, 62%, 62% and 67% for specificity, and 69.3%, 68.3%, 62.4%, 61.4% and 73.3% for accuracy, respectively. The highest negative predictive values (NPV) were obtained with BI-RADS and SUVmax (100% and 92%, respectively). No significant difference in malignancy rate was observed for the lesion size and age of the patients (p > 0.05).

CONCLUSION

There is a risk of detecting malignancy in incidental lesions showing 18F-FDG uptake. Radiological workup must be done, but SUVmax, with a high NPV value, can be used in conjunction with BI-RADS assessment for appropriate patient selection and effective management of resources.

The Investigation of Somatostatin Receptors as a Potential Target in Breast Phyllodes Tumours

BACKGROUND

Somatostatin receptors (SSTRs) are expressed in most neuroendocrine neoplasms, particularly in gastroenteropancreatic neuroendocrine tumours, and have been utilised as diagnostic markers and therapeutic targets. The radioiodinated somatostatin analogue 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid- Tyr3-octreotate (DOTATATE) has been employed for SSTR targeting for either diagnostic or therapeutic purposes depending on the labelling with 68Gallium or 177Lutetium, respectively. SSTR expression is reported in a subset of breast adenocarcinoma and breast neuroendocrine carcinomas; however, minimal knowledge exists regarding their expression in fibroepithelial (biphasic) breast lesions such as fibroadenoma and phyllodes tumours. Aggressive ends of the spectrum, i.e., "cystosarcoma phyllodes", may present a management challenge with recurrences and metastases, and SSTRs could be a promising therapeutic target for these types of tumours.

METHODS

Gene and protein expressions of SSTRs in primary human fibroepithelial lesions of the breast are investigated using RT-PCR and immunoblotting. Localisation of the SSTR-positive cells was determined with immunohistochemistry and immunofluorescence.

RESULTS AND CONCLUSIONS

Both fibroadenoma and phyllodes tumours express SSTRs. Immunohistochemical analyses suggested that this expression is in the stromal, not epithelial, component by demonstrating that SSTR stained in the areas overlapping with α-smooth muscle actin-positive myoepithelial cells around blood vessels and capillary structures. This study is the first in the literature to demonstrate SSTR positivity in mammary fibroepithelial neoplasms. Once validated, these findings may also have significant implications for managing the treatment of these tumours.

Detection of benign granular cell tumor of the breast via 18F-PSMA-PET/CT in a patient with very high-risk prostate cancer: A case report

Incidental extra-prostatic prostate-specific membrane antigen (PSMA) uptake on initial staging positron emission tomography/computed tomography (PET/CT) scans poses diagnostic challenges, as it can be associated with various benign and malignant lesions. We present the case of a 68-year-old man with very high-risk prostate cancer who was incidentally discovered to have a benign granular cell tumor in the breast initially detected on PSMA-PET/CT. Imaging studies and biopsy were pivotal in the diagnosis, as the tumor's appearance was concerning for breast carcinoma. Recognizing extra-prostatic PSMA uptake in the breast, particularly in patients with prostate cancer, is crucial for guiding appropriate management, accurately interpreting subsequent imaging findings, and assessing radiologic-pathologic correlation.

Diffuse Intense 18 F-PSMA-1007 Uptake of the Breasts in a Woman With TFE3-Rearranged Renal Cell Carcinoma

ABSTRACT

A 23-year-old woman presenting with gross hematuria was found to have a left renal mass suspicious for renal cell carcinoma on abdominal contrast-enhanced CT. An 18 F-PSMA-1007 PET/CT scan was performed for evaluating the renal mass. 18 F-PSMA-1007 PET/CT showed focal activity of the renal mass, which was a transcription factor E3-rearranged renal cell carcinoma proved after nephrectomy. Surprisingly, diffuse heterogeneous intense activity of the bilateral breasts and moderate activity of the right accessory breast was observed. There was no morphological abnormality of the bilateral breasts and right accessory breast on CT images, indicating physiological PSMA uptake.

Non-conventional and Investigational PET Radiotracers for Breast Cancer: A Systematic Review

Breast cancer is one of the most common malignancies in women, with high morbidity and mortality rates. In breast cancer, the use of novel radiopharmaceuticals in nuclear medicine can improve the accuracy of diagnosis and staging, refine surveillance strategies and accuracy in choosing personalized treatment approaches, including radioligand therapy. Nuclear medicine thus shows great promise for improving the quality of life of breast cancer patients by allowing non-invasive assessment of the diverse and complex biological processes underlying the development of breast cancer and its evolution under therapy. This review aims to describe molecular probes currently in clinical use as well as those under investigation holding great promise for personalized medicine and precision oncology in breast cancer.

An Unusual Presentation of Breast Implant Rupture

ABSTRACT

A 99mTc-methylene diphosphate (MDP) bone scintigraphy scan was performed to follow up metastatic breast cancer. A circular region of radiotracer uptake in the location of the patient's left breast implant was seen. Review of the same-day chest CT and the prior CT showed that the patient's breast implant had ruptured in the interim. The 99mTc-MDP uptake in the capsule of the breast implant was attributed to rupture, likely secondary to inflammation. This is an example of an unusual presentation of breast implant rupture discovered on a 99mTc-MDP bone scintigraphy scan.