Prognostic Level II. See Instructions for Authors for a complete description of levels of evidence.

Legg-Calvé-Perthes disease (LCPD) is a childhood hip disorder of ischemic osteonecrosis of the femoral head. Hip joint synovitis is a common feature of LCPD, but the nature and pathophysiology of the synovitis remain unknown. The purpose of this study was to determine the chronicity of the synovitis and the inflammatory cytokines present in the synovial fluid at an active stage of LCPD. Serial MRI was performed on 28 patients. T2-weighted and gadolinium-enhanced MR images were used to assess synovial effusion and synovial enhancement (hyperemia) over time. A multiple-cytokine assay was used to determine the levels of 27 inflammatory cytokines and related factors present in the synovial fluid from 13 patients. MRI analysis showed fold increases of 5.0 AE 3.3 and 3.1 AE 2.1 in the synovial fluid volume in the affected hip compared to the unaffected hip at the initial and the last follow-up MRI, respectively. The mean duration between the initial and the last MRI was 17.7 AE 8.3 months. The volume of enhanced synovium on the contrast MRI was increased 16.5 AE 8.5 fold and 6.3 AE 5.6 fold in the affected hip compared to the unaffected hip at the initial MRI and the last follow-up MRI, respectively. In the synovial fluid of the affected hips, IL-6 protein levels were significantly increased (LCPD: 509 AE 519 pg/mL, non-LCPD: 19 AE 22 pg/mL; p ¼ 0.0005) on the multi-cytokine assay. Interestingly, IL-1b and TNF-a levels were not elevated. In the active stage of LCPD, chronic hip synovitis and significant elevation of IL-6 are produced in the synovial fluid. Further studies are warranted to investigate the role of IL-6 on the pathophysiology of synovitis in LCPD and how it affects bone healing.

Neoadjuvant therapy in breast cancer can downstage axillary lymph nodes and reduce extent of axillary surgery. As such, accurate determination of nodal status after neoadjuvant therapy and before surgery impacts surgical management. There are scarce data on the diagnostic accuracy of breast magnetic resonance imaging (MRI) for nodal evaluation after neoadjuvant therapy in patients with invasive lobular carcinoma (ILC), a diffusely growing tumor type. We retrospectively analyzed patients with stage 1–3 ILC who underwent pre-operative breast MRI after either neoadjuvant chemotherapy or endocrine therapy at our institution between 2006 and 2019. Two breast radiologists reviewed MRIs and evaluated axillary nodes for suspicious features. All patients underwent either sentinel node biopsy or axillary dissection. We evaluated sensitivity, specificity, negative and positive predictive values, and overall accuracy of the post-treatment breast MRI in predicting pathologic nodal status. Of 79 patients, 58.2% received neoadjuvant chemotherapy and 41.8% neoadjuvant endocrine therapy. The sensitivity and negative predictive value of MRI were significantly higher in the neoadjuvant endocrine therapy cohort than in the neoadjuvant chemotherapy cohort (66.7 vs. 37.9%, p = 0.012 and 70.6 vs. 40%, p = 0.007, respectively), while overall accuracy was similar. Upstaging from clinically node negative to pathologically node positive occurred in 28.0 and 41.7%, respectively. In clinically node positive patients, those with an abnormal post-treatment MRI had a significantly higher proportion of patients with ≥4 positive nodes on pathology compared to those with a normal MRI (61.1 versus 16.7%, p = 0.034). Overall, accuracy of breast MRI for predicting nodal status after neoadjuvant therapy in ILC was low in both chemotherapy and endocrine therapy cohorts. However, post-treatment breast MRI may help identify patients with a high burden of nodal disease (≥4 positive nodes), which could impact pre-operative systemic therapy decisions. Further studies are needed to assess other imaging modalities to evaluate for nodal disease following neoadjuvant therapy and to improve clinical staging in patients with ILC.

e12604 Background: The safety of the sentinel lymph node biopsy procedure (SLNB) in the surgical management of breast cancer relies upon a false negative rate (FNR) being less than 10%. The accuracy of SLNB in invasive lobular carcinoma (ILC), the second most common type of breast cancer, has not been evaluated. Because of high rates of false negative imaging and the diffuse growth pattern in ILC, less accurate pre-operative staging and a potentially unreliable lymphatic drainage pattern may impact the accuracy of SLNB in this tumor type. We therefore sought to characterize the accuracy of SLNB in a cohort of patients with ILC. Methods: We queried an institutional database of 707 patients with ILC and identified 196 patients who underwent SLN mapping with excision of both sentinel and non-sentinel nodes. A false negative was defined as having negative sentinel lymph nodes and a positive non-sentinel node. We calculated the FNR and sensitivity of SLNB and evaluated clinicopathologic variables. Results: Of 196 cases, 183 were clinically node-negative, 9 were clinically node-positive, and 4 had unknown clinical node status. Of the 183 clinically node-negative patients, 69 (37.7%) patients had node-positive disease at surgery. Overall, 7 of 196 cases had false negative SLNB, yielding an FNR of 8.97%. The sensitivity of SLNB was 91%. Patients with a false negative SLNB were significantly older than patients without (mean age 63 versus 54.7 years, p = 0.041). Significantly fewer sentinel and non-sentinel nodes were removed in women aged 50 years or older compared to those under 50 (1.9 vs. 2.5 sentinel nodes, p = 0.0158; 4.7 vs. 7.9 non-sentinel nodes, p = 0.0077). There were no differences in tumor receptor subtype, grade, stage, presence of lymphovascular invasion, or receipt of neoadjuvant therapy in those with a false negative SLNB compared to those without. Conclusions: The high rate of nodal positivity in clinically node negative patients highlights the challenges of clinical nodal assessment in ILC. Despite this, the SLNB procedure had a FNR that fell within the acceptable range, supporting its use in ILC. The relationship between number of sentinel nodes removed and FNR deserves further study, particularly in older women where extent of nodal surgery continues to decline.

Background: The safety of breast conservation therapy (BCT) has not been demonstrated in large ILC tumors, potentially contributing to the higher mastectomy rates seen in ILC. Methods: We queried a prospectively maintained database to identify patients with ILC measuring 4 cm and evaluated difference in recurrence free survival (RFS) between those treated with BCT versus mastectomy using a multivariate model. Results: Of 180 patients, 30 (16.7%) underwent BCT and 150 (83.3%) underwent mastectomy. Patients undergoing mastectomy were younger (56.6 vs. 64.3 years, p ¼ 0.003) and had larger tumors (7.2 vs. 5.4 cm, p < 0.001). While tumor size, nodal stage, receptor subtype, and margin status were significantly associated with RFS, there was no difference in RFS at 5 (p ¼ 0.88) or 10 (p ¼ 0.65) years for individuals undergoing BCT versus mastectomy. Conclusions: For patients with ILC 4 cm, BCT provides similar tumor control as mastectomy, provided that negative margins are achieved. Published by Elsevier Inc.