NUT midline carcinoma in the state sector of the Free State province, South Africa
Roets, Antoinette Elisabeth
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Background: NUT midline carcinoma (NMC) is a recently described, rare tumour that can easily be mistaken for a number of other tumours if a NUT immunohistochemical stain is not performed. The tumour is caused by a translocation involving the NUT gene and most cases involve BRD4 - NUT t(15;19) which results in loss of differentiation and uninhibited proliferation. The loss of differentiation is responsible for the monomorphic, primitive morphology of the tumour. The reporting Pathologist should have a high index of suspicion as the tumour shows positively for numerous immunohistochemical markers that vary from case to case. Positivity for CD34, which is unusual in carcinomas, together with positivity for cytokeratins, is a strong diagnostic clue that should prompt testing for the tumour. Previously thought to occur only in midline structures and young patients, recent research has proven the occurrence in a wider age distribution and outside the midline. This tumour is exceptionally aggressive, with only isolated survivors and early identification and aggressive treatment is needed. No research on NMC has been done in South Africa and there is only one case report from the rest of Africa. The incidence of this tumour in South Africa is therefore unknown. Aim: The aim of this study was to determine the number of cases of NMC seen over a twelve year period by the Department of Anatomical Pathology, University of the Free State and National Health Laboratory Service and to describe the demographic features of any patients identified. Methods: A retrospective study was performed. All undifferentiated malignant tumours and tumours with evidence of squamous differentiation from the head, neck and thorax seen between 1 January 2005 and 31 December 2016 were included. A NUT immunohistochemical stain was performed on all cases. The stain was regarded as positive if there was speckled nuclear staining in more than 50% of the tumour cells. Results: Four hundred and ninety eight cases were included in the study of which 424 (85.1%) were male and 74 (14.9%) were female. The mean age was 58.6 years. Only one positive case was identified. The patient was a 30-year-old female with a lung mass and lymph node metastases. Conclusion: This study confirms the rarity of this entity. Additional research is needed in other provinces of South Africa, including the private sector to provide a comprehensive patient profile of NMC in South Africa.