Diagnostic Utility of TLE1 (Transducer-Like Enhancer of Split 1) in Distinguishing Synovial Sarcoma from Mimicking Tumors

Figures & data

Table 1 Frequency of Different Tumors Stained with TLE1 Antibody (n = 177)

Histological Diagnosis	Frequency (%)
Synovial sarcoma
● Monophasic	42 (47.2%)
● Biphasic	6 (6.7%)
● Poorly differentiated	41 (46.7%)
Non-synovial sarcoma tumors
● Ewing sarcoma	20 (30.7%)
● Leiomyosarcoma	13 (14.8%)
● Undifferentiated sarcoma	10 (11.4%)
● Fibrosarcomatous dermatofibrosarcoma protuberans	8 (9.1%)
● Malignant peripheral nerve sheath tumor	7 (8%)
● Embryonal rhabdomyosarcoma	4 (4.5%)
● Sarcomatoid carcinoma	4 (4.5%)
● Malignant solitary fibrous tumor	3 (3.4%)
● Epithelioid sarcoma	2 (2.3%)
● Malignant melanoma	1 (1.1%)
● Wilms tumor	1 (1.1%)
● Histiocytic sarcoma	1 (1.1%)
● Merkel cell carcinoma	1 (1.1%)
● Malignant phyllodes tumor	1 (1.1%)
● Inflammatory myofibroblastic tumor	1 (1.1%)
● Infantile rhabdomyofibrosarcoma	1 (1.1%)
● Fibromatosis	1 (1.1%)
● Cellular schwannoma	1 (1.1%)

Table 2 Comparison of Frequency of Overall TLE1 IHC Expression in Synovial Sarcoma and Non-Synovial Sarcoma Cases (n = 177)

Histological Groups	TLE1 Expression		p-value
	Positive	Negative
Synovial sarcoma	89 (100%)	0	<0.001
Non-synovial sarcoma	17 (19.3%)	71 (80.7%)

Table 3 Comparison of Frequency of Intensity of TLE1 IHC Expression in Synovial Sarcoma and Non-Synovial Sarcoma Cases (n = 177)

Histological Groups	TLE1 Expression				p-value
	Negative	Weak Positive	Moderate Positive	Strong Positive
Synovial sarcoma	0	2 (2.2%)	1 (1.1%)	86 (96.7%)	<0.001
Non-synovial sarcoma	71 (80.7%)	11 (12.5%)	2 (2.2%)	4 (4.5%)

Figure 1 TLE1 IHC staining in synovial sarcoma and Ewing sarcoma. (A) Poorly differentiated synovial sarcoma, H&E, 20x. (B) Strong positive nuclear TLE1 IHC expression in tumor cells, 20x. (C) Ewing sarcoma, H&E, 20x. (D) Negative TLE1 IHC expression in cells of Ewing sarcoma tumor cells, 20x.

Table 4 Summary of Intensity-Wise TLE1 Expression in Non-Synovial Sarcoma Entities Showing Positive TLE1 Expression

Histological Diagnosis	No. of Cases Stained	TLE1 Expression
		Negative	Weak Positive	Moderate Positive	Strong Positive
Ewing sarcoma	27	22	3	1	1
Leiomyosarcoma	13	11	2	–	–
Embryonal rhabdomyosarcoma	4	2	1	1	–
Epithelioid sarcoma	2	–	2	–	–
Undifferentiated sarcoma	10	8	1	–	1
Malignant melanoma	1	–	–	–	1
Sarcomatoid carcinoma	4	3	1	–	–
Malignant peripheral nerve sheath tumor	7	6	1	–	–
Cellular schwannoma	1	–	–	–	1

Figure 2 TLE1 IHC staining in cellular schwannoma and leiomyosarcoma. (A) Cellular schwannoma, H&E, 20x. (B) Strong nuclear TLE1 expression in tumor cells of cellular schwannoma, 20x. (C) Leiomyosarcoma, H&E, 20x. (D) Moderate nuclear TLE1 expression in tumor cells of leiomyosarcoma, 20x.

Figure 3 TLE1 staining in malignant melanoma. (A) Malignant melanoma, H&E, 20x. (B) Strong nuclear expression of TLE1 IHC stain in melanoma cells, 20x.