LGI1 and histiocytic sarcoma: Anti-LGI1-IgG1/2/3 antibodies were significantly more frequent in patients who later developed HS (p = 0.002, Fisher’s exact text, two-tailed); the sensitivity of the anti-LGI1-IgG1/2/3-subclass status predicting HS was 0.67 (95% confidence interval [CI] 0.30–0.93), the specificity 1.00 (95% CI 0.72–1.00), the positive predictive value 1.00 (95% CI 0.54–1.00), and the negative predictive value 0.79 (95% CI 0.49–0.95).