SMARCB1/INI-1 deficient sinonasal carcinoma: An emerging entity

Abstract

SMARCB-1 deficient sinonasal carcinoma are a group of highly aggressive carcinoma of the sinonasal tract described as an emerging and rare among the group of poorly differentiated/undifferentiated subset of sinonasal carcinoma. They shows a diverse range of morphological feature which comes as a challenge to the reporting pathologist, however with the knowledge and awareness of this emerging entity and prompt use of immunohistochemistry marker for INI-1, an early diagnosis can be made, which is very crucial for subtyping undifferentiated carcinoma and further improve the management strategy and even help in defining targeted therapy. In this report, we describe an additional case of SMARCB1 (INI1)-deficient sinonasal carcinoma in 35-year-old man presenting with a large painless, progressively enlarging nasal mass with epistaxis, proptosis and diplopia. Computed tomography displayed a large mass occupying the entire nasal cavity with destruction of orbital floor and maxillary sinus. An incisional biopsy was performed. A complete loss of nuclear SMARCB1 (INI-1) expression in tumor cells was seen and the diagnosis of SMARCB1 (INI1)-deficient sinonasal carcinoma was finally established, due to aggressive behaviour of the disease patient died within five days of final diagnosis. The aggressive nature and poor prognosis of the entity, targeted therapies are required in this era of precision medicine which further necessitates the awareness, early diagnosis and reporting of this rare entity.