Branchial Cleft Cyst Carcinoma Remains Grossly Over Diagnosed: A Large Database Analysis

Introduction: Branchial cleft cyst carcinomas (BCCC) are rare lateral neck malignancies thought to originate from branchial cleft remnants. Diagnosing primary BCCC should be approached with skepticism; cystic nodal metastasis must be excluded. Due to its rarity, we performed a comprehensive database study to better characterize the ongoing diagnosis of BCCC. Methods: Single-arm retrospective cohort study using the TriNetX Research database. Patients ≥ 18 years of age with a diagnosis of BCCC identified by ICD-10 C10.4 between 2008 and 2018 were included, allowing for up to 5 years of follow-up. Demographics, past medical history, oncologic history, diagnostic rate, treatment pathways, and 5-year outcomes including diagnosis with primary HNC and Kaplan–Meier survival curves were analyzed within TriNetX. Results: In 10 years, 1070 patients diagnosed with BCCC were included. The mean age was 59.6 ± 9.7; the majority were male (n = 810, 75.6%) and white (n = 765, 71.4%). Incidence of BCCC increased from 2008 to 2015 and subsequently dropped precipitously. Almost all patients, 94.4% (n = 1011), had prior or subsequent diagnosis of another HNC within 5 years. Five-year survival probability for BCCC was 56.0%. Conclusions: We describe the largest cohort of BCCC patients to date. Most patients were diagnosed with another HNC within 5 years, suggesting a likely misdiagnosis of BCCC. A poor 5-year survival rate may be secondary to a delay in appropriate treatment following an erroneous diagnosis, underscoring the need to approach a diagnosis of BCCC with caution. We consider the use of the BCCC code to be detrimental and recommend its discontinuation. Level of Evidence: 4.