Fine-needle aspiration of intramammary lymph nodes: a clinical, radiographic, and cytologic review

Introduction: Recognizing and sampling intramammary lymph nodes (IMLNs) is important in the clinical management of patients with breast carcinomas. We undertook a retrospective study to evaluate the clinical utility of fine-needle aspiration (FNA) in assessing IMLNs. Materials and methods: Our pathology database was searched for all IMLN FNA cytology cases from January 2005 to December 2021. The cytologic findings, radiographic features, and clinical data were reviewed. Results: A total of 149 cases were identified. Eighteen of 149 (12%) patients had synchronous breast tumors, including 13 invasive ductal carcinomas (IDCs), 1 ductal carcinoma in situ (DCIS), and 4 fibroadenomas. Among patients with synchronous IDCs, FNA of IMLNs was positive for metastatic carcinoma in 4 of 13 (30.7%) cases. The 4 patients with positive IMLNs all received mastectomies. Fifteen of 149 (10.7%) patients had a prior history of breast tumors, including 9 IDCs, 4 DCISs, 1 lobular carcinoma in situ (LCIS), and 1 fibroadenoma. Two of 149 (1.3%) patients had a prior history of lymphoma. In the patients with prior history of IDC, DCIS, LCIS, lymphomas and fibroadenomas, IMLN FNAs were all negative for malignancy. Two of 149 cases (1.3%) showed granulomatous lymphadenitis. The remaining 112 cases had negative IMLN FNAs and no significant clinical or pathological findings. Conclusions: Our study showed that IMLNs are commonly associated with synchronous/metachronous breast tumors (33 of 149, 22.1%). The incidence of positive IMLN FNA in patients with synchronous invasive breast carcinoma was 30.7% (4 of 13). FNA of IMLNs in conjunction with clinical presentation and radiologic findings allows triage of patients for appropriate clinical management and avoids additional unnecessary surgical procedures.