Table 2:

Histologic, Immunophenotypic and Molecular Features

Case	Tumor component	Nuclear Grade	Mitotic rate (per 10 HPF)	Immunophenotype						Mutated cancer driver genes	Fraction of genome altered (%)	Proportion of somatic variants shared/truncal (%)
				Pax8	WT1	ER	PR	p16	p53
1	SBT (ovary)	1	2	+	+	+	+/−	Het	WT	KRAS	0.62	26
	HGSC (ovary)	3	13	+	+	+	+/−	Het	Abn. (cyto)	KRAS, TP53	100†	25
2	SBT (ovary)	1	2	+	+	+/−	+/−	Het	WT	KRAS	14	33
	IGSC (rec)	2	14	+	+	+/−	-	Diff	WT	KRAS	30	26
3	LGSC (ovary)	2	3	+	+	+	+/−	Het	WT	KRAS	100†	18
	LGSC (lymph node)	2	0	+	+	+	+/−	Het	WT	KRAS	37	32
	HG. Ca. (rec)*	3	17	+	-	-	-	Het	WT	KRAS	100†	28
4	SBT (ovary)	1	3	+	+	+/−	+	Het	WT‡	BRAF, TP53	5.9	38
	HGSC (ovary)	3	12	+	+	+/−	+/−	Diff	Abn. (Diff.)	BRAF, TP53	28	21
	HGSC (lymph node)	3	14	+	+	+/−	+/−	Diff	Abn. (Diff.)	BRAF, TP53	22	29
5	miSBT (ovary)	1	2	+	+	+	+/−	Null	WT	NF1, NF2, ATRX	8.9	33
	IGSC (diaphragm)	2	13	+	+	+	+/−	Null	WT	NF2, ATRX	14	18
	HGSC (rec)	3	22	+	+	-	-	Null	WT	NF2, ATRX, TP53	21	9.4
6	miSBT (ovary)	1	0	+	+	+	+	Het	WT	None	0.10	43
	LGSC (ovary)	1	0	+	+	+	+	Het	WT	None	25	58
	IGSC (rec)	2	23	+	+	+	-	Het	WT	None	32	39
	LGSC (rec)	1	3	+	+	+	-	Null	WT	CDKN2A (del)	27	29
7	LGSC (ovary)	1	0	+	+/−	+	+/−	Het	WT	KRAS, USP9X	82	50
	Undiff. Ca. (rec)	3	3	-	-	-	-	Het	WT	KRAS, USP9X	97†	41

Abbreviations: Abn – abnormal expression pattern, (cyto - cytoplasmic; Diff – diffuse); Het – heterogeneous expression; HGSC – high-grade serous carcinoma; IGSC – indeterminate grade serous carcinoma; HG. Ca. – high-grade (Mullerian) carcinoma; LGSC – low-grade serous carcinoma; miSBT – micropapillary serous borderline tumor; Null – null expression pattern; rec – recurrence; SBT – serous borderline tumor; Undiff. Ca. – undifferentiated (sarcomatoid) carcinoma; WT – wildtype expression pattern. +, Positive staining (patchy-to-diffuse, moderate to strong intensity); +/–, Focal staining (weak; up to moderate intensity in occasional cells); –, Negative staining.

^*Additional immunohistochemical stains for GATA3 and TTF1 are negative, ruling out mesonephric differentiation.

^‡Scattered foci with diffuse p53 overexpression present.

^†Whole genome duplication present.