Anales de la RANM

94 A N A L E S R A N M R E V I S T A F U N D A D A E N 1 8 7 9 CONTRIBUTION OF 18F-FDG PET/CT IN OCCULT BREAST CARCINOMA Valhondo-Rama, et al. An RANM. 2021;138(01): 92 - 95 PATIENT 2: In December 2018, high CEA value was detected during the follow-up of a 73-year-old woman with previous sigma and endometrial adenocarcinoma surgically treated. Body-CT spotted a pathological adenopathy in right axilla whose biopsy suggested tumour from female genital tract, without ruling out pancreas or gastrointestinal origin. In January 2019, colonoscopy and oral panedoscopy were normal. WB 18 F-FDG PET/CT (February 2019) showed multiple right axillary lymphadenopathies and incidental FDG uptake in a hypodense nodule in the left thyroid lobe (Figure 3) . US guided FNAC of the thyroid nodule was compatible with Bethesda 4 follicular neoplasm, pending surgery until treatment of OBC is completed. Biopsy of the largest axillar y adenopathy repor ted metastasis of Luminal A breast adenocarcinoma. With the diagnosis of right OBC, ipsilateral axillar y lymphadenectomy was carried out (8 of 13 nodes positive). She began adjuvant Letrozole and adjuvant RT (50Gy on right breast, axilla and supraclavicular region). Chemotherapy was dismissed because of multiple comorbidities. CEA value remains high (13.7 ng/mL on December 2020, normal range 0.1-5.0) but last WB 18 F-FDG PET/CT ( Januar y 2021) confirms disease stabilization. Breast tissue persists without lesions. Increased FDG uptake was obser ved in the thyroid nodule. Surger y has been rejected for the moment by the patient because of COVID-19 pandemic situation. She continues maintenance therapy with Letrozole. This study involving human beings is in accord- ance with the ethical standards of institu- tional and national research committees and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards. The two patients signed a generic consent for 18 F-FDG PET/CT. Occult breast carcinoma (OBC) was classified by the American Joint Committee on Cancer (AJCC) as cT0, cN1-2, M0, Stage II–III. However, its prognosis seems better than stage II palpable breast carcinoma. After axillary lymph node metastases, the time of appearance of primary breast cancer varies from 0.5 to 5 years. Early identification of the primary site and its appropriate staging and management result in better prognosis. (1,6,7) MRI has achieved a sensitivity of 89% with 74% of specificity (1,3–5). When combining MM, US and MRI the sensitivity goes up to 99.4%.(8) Blood tumour markers have also a role,(3) as showed in our patients. WB 18 F-FDG PET/CT has lower spatial resolution than MRI (sensitivity 63%, specificity 91%)(1,3,10) However, several authors confirm its efficacy to explore in only one examination several lymph node stations and distant metastasis and to rule out other primary sites.(1–4,9) In our patients, stage IV was early diagnosed in Patient 1 thanks to pathological metabolic activity in a non-enlarged subcarinal lymph node. In Patient 2, the PET/CT study did not change the diagnosis and staging of OBC but another primary neoplasm was early detected. WB 18 F-FDG PET/CT seems especially useful when dense breasts, multicentric disease and/or breast prostheses. Regarding the therapeutic approach, the traditional choice was like primary breast cancer with nodal metastases: systemic chemotherapy, mastectomy, and axillary lymph nodes dissection. However, the impact of mastectomy on survival is not clear and histopathological examination of the mastectomy specimen do not reveal the primary tumour in one third of patients.(1,6-8) Current National Comprehensive Cancer Network (NCCN) Guidelines® recommend modified radical mastectomy, with the option of breast preservation plus radiation for N1 patients. Johnson et al(7) proved that breast preservation plus RT is reasonable regardless of nodal stage, with similar or even better overall survival comparing to mastectomy. Some studies also suggest that only Figure 3. Patient 2. WB18F-FDG PET/CT, axial planes, (A) CT, (B) PET/CT, (C) PET. Focal FDG uptake in an incidental thyroid nodule (blue arrows) sized 1.2cm, SUVmax 9.3. DISCUSSION