To study the clinical-diagnostic meaning of accidental breast uptake of 18F-FDG during PET performed for other diseases, mainly cancer, correlating with radiological imaging and histopathology.
We retrospectively selected 43 patients (7 males and 36 females). They were investigated with mammary and axillary clinical examination, mammography (MMX), UltraSound (US) and/or Magnetic Resonance (MRI). Cases suspected for breast malignancy were studied with US-guided macro-biopsy (USMB). Patients were primitively affected by lung cancer (15), NHD (8), melanoma (4), head-neck cancer (2), other diseases (13) as well as ampullary cancer, Burkitt’s lymphoma, CUP Syndrome, esophageal cancer, GIST, T lymphoma, occult tumour, sarcoma, thyroid cancer, tonsil cancer, rectal cancer, vasculitis. A correlation between PET (SUV), radiology (imaging and BI-RADS classification), age, histopathology was done.
Of 43 patients analyzed, 19 performed the deepening of mammary finding using US and MMX, 11 performed only US, 13 did not perform nothing because they did not carry on the follow-up. Of 11 patients who performed US, 6 did not perform the deepening USMB because unnecessary, instead 5 performed USMB. Eight patients of 30 who carried out the study of the radiological findings on mammary gland did not show morphological abnormalities. Histopathology of 22 eligible patients showed: 9 infiltrating ductal carcinomas, 4 lymphomas (including 1 skin), 1 adenoidcystic cancer, 1 carcinomatous mastitis, 6 fibroadenomas and 1 phyllodes tumour. Thirteen patients did not keep on the follow-up because of death (4) or lost in time (9). Out of 22 patients studied, we found 7 with SUVmax >2.5 and 15 with SUVmax <2.5 (average SUV= 2.0233±2:38SD). There was not statistically significance (p=0.361) between SUVmax and histology. The incidence of malignancy was 68.2%. The incidence of benignity was 31.8%. We did not found a significant correlation (p< 0.106) between SUVmax and radiological imaging. We did not see a significant correlation (p<0.356) between patient age and tumour characterization. BI-RADS classification (evaluated by CT images for attenuation correction of PET) did not correlate with final histology. In 8 cases PET finding was not confirmed radiologically for the occurrence of artifacts from breast movement during PET or physiological distribution of 18F-FDG in the mammary gland related to menstrual cycle.
From our experience the identification of an accidental mammary uptake during PET may represent an “alarm bell” (68.2% of malignancy) inducing to deepen PET findings. It seems to have a clinical implication because of the change of patient treatment. The diagnostic anticipation would have a favorable prognostic value and lead to a significant reduction in costs. Our data must be confirmed in a more large casuistic.