Distant Cutaneous Metastasis of Chordoma: A Systematic Review and Individual-Participant-Data Meta-Analysis of 52 Cases, with an Illustrative Poorly Differentiated Index Case.

Chordoma is a rare notochordal malignancy of the axial skeleton, and distant cutaneous metastasis is among its rarest manifestations-an under-recognised mimic of benign and malignant skin tumours that often presents with an incomplete clinical history.

methodsWe performed a systematic review and one-stage individual-participant-data (IPD) meta-analysis of all reported cases of distant cutaneous chordoma metastasis, following PRISMA 2020, and complemented it with an illustrative index case of cutaneous poorly differentiated chordoma in a young adult. Missing case-level data were handled by available-case analysis without imputation, with denominators reported throughout. Pooled prevalences were estimated by logistic-normal random-effects models (heterogeneity by I

resultsForty reports (52 cases) were included; individual data were analysable in 43. Median age was 59 years (range, 2 months-88), male-to-female ratio 2.3:1, sacrococcygeal primary 74% (31/42) and median latency 4.0 years (synchronous to 15). Physaliphorous cells, myxoid stroma and vacuolated cytoplasm dominated, yet brachyury and SMARCB1/INI1 were documented in only 6/52 and 1/52 cases. Pooled prevalences were 74% (95% CI 59-85) for a sacrococcygeal primary, 70% (55-82) for male sex and 77% (62-87) for physaliphorous morphology, with no between-report heterogeneity (I

conclusionsDistant cutaneous chordoma metastasis is a late event that usually signals disseminated disease and a limited life expectancy, commonly months to a few years. Its recognition rests on integrating morphology with nuclear brachyury and, in epithelioid or young presentations, SMARCB1/INI1. We provide a differential-diagnostic framework and algorithm, distinguishing cohort-supported findings from expert interpretation.