Nuclear protein of the testis midline carcinoma in the oral cavity: retrospective review of those initially diagnosed as poorly differentiated squamous cell carcinoma using an anti-C52B1 antibody

Oral and oropharyngeal NUT carcinoma: a multicentre screening study of poorly differentiated oral cancer

BACKGROUND AND AIMS

Nuclear protein testis (NUT) carcinoma (NC) is a rare and highly aggressive tumour characterised by chromosomal rearrangement of the nuclear protein testis family member 1 (NUTM1) gene, also known as the NUT gene. NC occurs mainly in the head and neck, mediastinum and lung. In general, primary NC in the oral cavity is extremely rare and reported sporadically.

METHODS

A total of 111 formalin-fixed and paraffin-embedded specimens of poorly differentiated oral and oropharyngeal tumours were collected from 10 hospitals. NUT protein IHC staining was performed on these samples, and fluorescence in-situ hybridisation (FISH) and RNA sequencing detection were further carried out for NUT IHC-positive cases.

RESULTS

The expression of NUT protein in tumour cells was detected in five cases (five of 111, 4.5%). The tumours in these cases were located in the oral floor, lip, base of the tongue, gingiva and hard palate. FISH detection results showed BRD4::NUT rearrangement in three patients and a non-BRD4::NUT rearrangement pattern in two patients. RNA sequencing results confirmed BRD4::NUT rearrangement in two cases.

CONCLUSIONS

To our knowledge, this is the first and largest retrospective study of oral NC, and we found that NC is easily misdiagnosed as poorly differentiated oral squamous cell carcinoma (SCC) or poorly differentiated carcinoma. The morphology and immunophenotype of four NC cases were similar to SCC, and abrupt keratinisation was observed in three cases. Therefore, it is necessary to detect NUT protein for NC screening in oral malignant tumours with these morphologies, especially for young patients who are more likely to be misdiagnosed with other types of cancer.

Large cell neuroendocrine carcinoma on the floor of the mouth: a rare entity in an unusual location

Neuroendocrine carcinomas (NEC) are a group of malignant neoplasms usually located in the lungs or gastrointestinal tract. Fewer cases are located in the head and neck, and in these rare presentations, the lingual tonsil, larynx, and major salivary glands are the most frequently affected sites. NECs exhibit similar characteristics regardless of where they arise. However, because these neoplasms are rare, a clear understanding of their aetiopathogenesis has yet to be described, and options for treatment have varied and are not unified. A rare NEC of the floor of the mouth is reported here; it appears that this location has not been reported previously. The diagnosis was established through histopathological analysis, and the patient underwent systemic treatment. He had a partial response to treatment in the first 3 months, but died 6 months after the initial diagnosis. This highly uncommon tumour can pose a significant diagnostic challenge for clinicians and pathologists alike and can result in diagnostic delay.

Advances in the pathogenesis and treatment of nut carcinoma: a narrative review

NUT carcinoma (NC) is a rare, highly invasive and fatal tumor and often misdiagnosed. It typically arises from the mediastinum and midline organs and has complicated pathogenesis and poor outcome. Genetically, its pathogenesis is related to a chromosomal rearrangement involving the NUTM1 gene. In most cases, the main oncoprotein is BRD4-NUT with a translocation between NUTM1 and BRD4 genes, but in a few cases, the oncoprotein is BRD3-NUT, or NSD3-NUT. Studies have shown that the histone hyperacetylation and BRD4 hyperphosphorylation may lead to the activation of cancer circuits. Abnormal production of microRNA, inactivation of tumor suppressor genes and abnormal activation of several signaling pathways are proposed as potential mechanisms underlying the pathogenesis of NC. Currently, there is no consensus on its standard treatment for NC. Extent of surgical resection with negative margins, initial radiotherapy and part of chemotherapy regimens may significantly associated with the improvement of progression-free survival (PFS) rate and overall survival (OS) rate. Some bromodomain and extraterminal inhibitors (BETis) have shown encouraging results in the clinical trials on NC, but delayed drug resistance is still an important issue that needs to be resolved. Histone deacetylase inhibitors are also found to possess the potential in the treatment of NC. Herein, we summarize recent advances in the pathogenesis and treatment of NC.

Prevalence of NUT carcinoma in head and neck: Analysis of 362 cases with literature review

BACKGROUND

Nuclear protein in testis (NUT) carcinoma is a poorly differentiated carcinoma defined by the presence of NUT gene rearrangement. In the head and neck, the true prevalence of NUT carcinoma is unknown.

METHODS

We retrospectively investigated NUT expression with clinicopathologic features in 362 patients of poorly differentiated or undifferentiated carcinomas in the head and neck, and reviewed the literature reports.

RESULTS

Four (4/362, 1.1%) cases showed strong nuclear expression for NUT-specific monoclonal antibody, and all these tumors were in the sinonasal tract (4/40, 10%). The clinical outcome and histology were diverse unlike previously described. Although previous studies reported different frequency results according to study subjects, frequencies in sinonasal tract are relatively constant (10/80, 12.5%).

CONCLUSIONS

This is the largest study on the prevalence of NUT carcinoma in head and neck areas. It is important to include in the differential diagnosis of poorly differentiated carcinoma, particularly in the sinonasal tract.