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Table 3 Malignancies with Positive or equivocal (n=12) Internal (in-house) Pan-TRK IHC expression and NTRK NGS results

From: Validation and interpretation of Pan-TRK immunohistochemistry: a practical approach and challenges with interpretation

Tumor location

Tumor diagnosis

NTRK NGS

Pan-TRK IHC

Reference lab

Pan-TRK IHC

In-house

Parotid gland

Secretory carcinoma

ETV6-NTRK3

Positive

Positive (nuclear, 2+, 5%)

Parotid gland

Secretory carcinoma

ETV6-NTRK3

Positive

Positive (cytoplasmic, 1+, 20%)

Parotid gland

Secretory carcinoma

ETV6-NTRK3

Positive

Positive (cytoplasmic 1+, 100%; rare, focal nuclear staining, 2+, peripherally)

Parotid gland

Secretory carcinoma

ETV6-NTRK3

Positive

Positive (cytoplasmic, peripherally, 1+, 5%)

Parotid gland

Secretory carcinoma

ETV6-NTRK3

Positive

Positive (nuclear, peripherally, 2+, 15%)

Submaxillary gland

Secretory carcinoma

ETV6-NTRK3

Positive

Positive (cytoplasmic 1+, 100%; scattered nuclear, 2+)

Lung

Metastatic MEC

ETV6-NTRK3

Positive

Positive (cytoplasmic and nuclear staining, 1-2+, 100%)

Breast

Secretory carcinoma

ETV6-NTRK3

Positive

Positive (nuclear and cytoplasmic, 2-3+, 70%)

Soft tissue-popliteal area

MPNST

TPM4-NTRK3

Positive

Positive (cytoplasmic, 3+, 80%)

Soft palate

Polymorphous adenocarcinoma

No fusion detected

Positive

Positive (cytoplasmic, 2+, 90%)

Pleural fluid

Metastatic carcinoma, unknown origin

N/A

Positive, Focal

Equivocal (punctate, 1%)

Ovary

HGSC

NTRK1 truncation- intron 2

Positive, Focal

Equivocal  (punctate, 5%)

  1. Abbreviations: MPNST malignant peripheral nerve sheath tumor, HGSC high-grade serous carcinoma, MEC mucoepidermoid carcinoma, N/A not tested