Table 1. Demographics of patients with AST patients.

Patient	Gender	Age	Pathological diagnosis	# of lesions	Tissue*	Location	Somatic mutation(Fractional abundance §)
1 †, ‡	F	11	AST	1	im	calf	ND
2 †,‡	M	34	AST	1	im	shoulder	PI3KCA p.E542K (WTL: 10.25; EC: 50.65; SC: none)
3 †,†	M	16	AST	1	im	calf	PI3KCA p.H1047R (WTL: 18.80; EC: 44.00; SC: none)
4 †, ‡	F	16	AST	1	sc	shin	PI3KCA p.H1047L (WTL: 8.30; EC: 48.95; SC: none)
5†	F	17	AST	1	im	back	ND
6	M	34	AST	1	im	thigh	ND
7	M	17	AST	1	im	thigh	PI3KCA p.E542K (WTL: 7.32)
8	F	31	AST	1	im	thigh	PI3KCA p.H1047R (WTL: 5.07)
9	F	22	AST	1	im	thigh	PI3KCA p.H1047R (WTL: 13.10)
10	F	13	AST	1	im, sc	foot	PI3KCA p.E545K (WTL: 11.65)
11	M	19	AST	1	im	thigh	PI3KCA p.H1047R (WTL: 8.89)
12	M	13	AST	1	im, sc	ankle	PI3KCA p.H1047R (WTL: 12.60)
13	F	23	AST	1	im	calf	PIK3CA p.Y644H ¶
14	F	41	AST	1	sc	shin	ND
15	F	25	AST	1	im	foot	PI3KCA p.E545K (WTL: 8.93)
16	F	16	AST	1	im, sc	ankle	PI3KCA p.H1047R (WTL: 5.98)
17	F	46	AST	1	im, sc	back	PI3KCA p.E542K (WTL: 9.83)
18	F	18	AST	1	im, sc	ankle	PI3KCA p.E545K (WTL: 11.35)
19	F	13	AST	1	im	calf	ND
20	F	24	AST	1	im, sm	thigh	PI3KCA p.E542K (WTL: 5.64)

^*Tissue: im, intramuscular; sc, subcutaneous; sm, synovial membrane.

^†ECs and SCs isolated for cell experiments.

^‡used in RNA-seq experiment.

^§Fractional abundance of the mutation in WTL, whole tissue lysate; EC, endothelial cells; SC, intervascular stromal cells; ND, not detected.

^¶mutation detected by whole-exome sequencing.