Background: Clear cell sarcoma (CCS), epithelioid sarcoma, and synovial
sarcoma are rare tumors historically identified as high risk for lymph
node metastasis. Nodal metastasis in adults with these subtypes has been
described. This study investigates incident nodal metastasis and
associated survival in children with these subtypes. Procedure: Using
the National Cancer Database (2004-2015), we created a retrospective
cohort of 1303 patients (aged ≤25 years) who underwent local control
therapy for CCS, epithelioid sarcoma, and synovial sarcoma. Kaplan-Meier
curves estimated overall survival (OS) by subtype. Stratifying on
subtype, Cox regressions assessed OS by lymph node sampling status and
nodal metastasis. Results: There were 103 (7.9%) patients with CCS, 221
(17.0%) with epithelioid sarcoma, and 979 (75.1%) with synovial
sarcoma. Lymph node sampling was more frequent in patients with CCS
(56.3%) and epithelioid sarcoma (52.5%) versus synovial sarcoma
(20.5%, p<0.001). Synovial sarcoma metastasized to lymph
nodes less frequently than CCS or epithelioid sarcoma (2.2% vs. 14.6%
and 15.0%, p<0.001). Across all subtypes, lymph node
metastasis was associated with inferior OS (HR 2.10, CI 1.44-3.07,
p<0.001). Lymph node sampling was associated with improved OS
in CCS (HR 0.35, CI 0.15-0.78, p=0.010), inferior OS in synovial sarcoma
(HR 1.60, CI 1.13- 2.25, p=0.007), and no statistical association with
OS in epithelioid sarcoma. Conclusions: Lymph node metastasis is rare in
children with synovial sarcoma. Lymph node sampling procedures were not
consistently performed for patients with CCS or epithelioid sarcoma, but
improved OS supports routine lymph node sampling in children with CCS.
Biphasic synovial sarcoma with a striking morphological divergence from the main mass to lymph node metastasis
