TTF-1

TTF-1

A protein encoded by NKX2-1 on chromosome 14q13. TTF-1 is the term  preferred by pathologists for this protein; it is also widely used in immunohistochemistry for identifying thyroid or lung as sites of origin for tumours of unknown primary sites.
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Squamous, adenocarcinoma and small cell carcinoma of lung are common malignancies affecting lung and for that basic IHC panel markers like P63, TTF-1, Napsin A, CK 7, CK 20 and EGFR should be performed.
An immunocytochemical (ICC) panel including thyroid transcription factor 1 (TTF-1) and thyroglobulin (thyroid markers) combined with CD10, RCC antigen, and carbonic anhydrase IX (CAIX) (RCC markers) has been suggested to help in such cases.
Immunohistochemical staining were carried out on the cell block and core biopsy sections using antibodies to thyroid transcriptor factor-1 (TTF-1), Napsin-A, Thyroglobulin, CD10, PAX 8, AMACR, CA19-9 and CD57 (Automated Ventana Bench Mark machine, the EnVisionTm System).
The samples were stained with hematoxylin and eosin and the diagnosis was confirmed by immunochemistry using TTF-1, CK7 and napsin A panel of antibodies for adenocarcinoma confirmation and p63 and CK5/6 antibodies to exclude squamous cell carcinoma.
Immunostaining of the tumor was performed with TTF-1, CK7, and CK20, all of which were positive (Figure 3).
Simultaneously, several studies have shown that thyroid transcription factor-1 (TTF-1), also known as Nkx2.1, contributed substantially to the regulation of SP-A expression in ATII cells [12-14].
Histopathological examination using hematoxylin-eosin stain revealed adenocarcinoma (Figure 5); thyroid transcription factor-1 (TTF-1) was positive (Figure 6).
The poorly differentiated papillary thyroid carcinoma component was positive for TTF-1, thyroglobulin, and PAX8 while the squamous cell carcinoma was positive for p63, PAX8 (focally), and TTF-1 (very focally positive) and negative for thyroglobulin (Figures 2(a) and 2(b)).
In immunochemical study, the round cells were positive for thyroid transcription factor-1 (TTF-1) and epithelial membrane antigen (EMA) and negative for cytokeratin (Figures 2(d), 2(e), and 2(f)).
A SRS (sensitivity 80% to 90%) should be performed to exclude other tumour locations.[sup.10] The literature mainly focuses on the gastrointestinal tract as the primary site for a metastatic NET to the testes.[sup.2] In this case, the SRS was negative and the primary site could have been missed if a CT scan of the thorax and additional histological investigations, like a TTF-1, would not have been performed.
(17) Another study reported 74.6 % sensitivity using antibodies TTF-1 and p63.
The tumor was focally positive for CD68 (Table 2) and negative for CD45, CD1a, PAX5, CD34, CD117, CD15, CD23, CD4, HMB45, CK20, CK7, synaptophysin, chromogranin, CDX-2, PSA, PSAP, and TTF-1 (Table 3).