Results: Six out of twelve syndromic HS patients carried a heterozygous variant c.−208 A ≥ C (rs41264459), located on the promoter region of the AIM2 gene, with a minor allele frequency of 0.25, which is much higher than that reported in 1000 G and GnomAD (0.075 and 0.094, respectively). This evidence concerns the gene AIM2 and histiocytic sarcoma.