NUT carcinoma of the sinonasal tract infiltrating the orbit in a man with birdshot chorioretinitis

A 48-year-old man with a history of birdshot chorioretinitis presented with blurry vision, retro-bulbar pain and sinusitis. Though visual acuity was unaffected, he had left optic disc oedema and mild restriction of left eye abduction. His symptoms progressed quickly, with diplopia in primary gaze, epistaxis from his left nostril, and a left relative afferent pupillary defect (RAPD). On computed tomography, there was a mass in the nasal cavity that extended through the left cribriform plate and lamina papyracea and posteriorly into the optic canal. Pathological examination of biopsy specimens revealed sheets of undifferentiated cells with extensive areas of necrosis and islands of squamous differentiation. The tumour cells expressed monokeratin, p63, CD34, and p16. Molecular testing indicated rearrangement of the NUTM1 (15q14) locus and fusion of the NUTM1 and BRD4 (19p13.12) loci, confirming the diagnosis of NUT carcinoma of the sinonasal tract. This is the first reported case of NUT carcinoma in a patient with birdshot chorioretinitis. The onset of chorioretinitis may have been the earliest sign of the effects of the BRD4-NUTM1 fusion protein, resulting in expression of HLA-A29. There is evidence that bromodomain and extra terminal (BET) family proteins play a role in inflammatory marker expression.