Shipra Agarwal1, Aanchal Kakkar1, Nishikant A Damle2, Chitresh Kumar3, Jayati Sarangi1, Kishan Subudhi2, Deepali Jain1, Mehar C Sharma4. 1. Department of Pathology, All India Institute of Medical Sciences, New Delhi - 110029, India. 2. Department of Nuclear Medicine, All India Institute of Medical Sciences, New Delhi - 110029, India. 3. Department of Surgical Oncology, National Cancer Institute, All India Institute of Medical Sciences, Jhajjar, India. 4. Department of Pathology, All India Institute of Medical Sciences, New Delhi - 110029, India. Electronic address: sharmamehar@yahoo.co.in.
Abstract
BACKGROUND: Biallelic loss of SMARCB1/INI1 is associated with highly aggressive malignancies, namely renal and extra-renal malignant rhabdoid tumors, and atypical teratoid/ rhabdoid tumor. Increasing availability of molecular testing and immunohistochemical stains acting as surrogate tools to genetic analysis has led to an increasing recognition of SMARCB1 loss in a variety of neoplasms. Interestingly, many of these lack the typical rhabdoid features ascribed to this group of tumors, making their identification difficult. CASE PRESENTATION: We describe the cytological, histological, immunohistochemical and molecular features of the first case of primary SMARCB1 (INI1)-deficient carcinoma of the thyroid gland in literature. The tumor was unique in various aspects; apart from never having been documented at this location, it showed extensive glandular differentiation, mimicking metastatic adenocarcinoma. CONCLUSION: Awareness of this novel entity is essential to avoid misdiagnosis, and for appropriate management, especially in an era of increased feasibility of targeted therapy.
BACKGROUND: Biallelic loss of SMARCB1/INI1 is associated with highly aggressive malignancies, namely renal and extra-renal malignant rhabdoid tumors, and atypical teratoid/ rhabdoid tumor. Increasing availability of molecular testing and immunohistochemical stains acting as surrogate tools to genetic analysis has led to an increasing recognition of SMARCB1 loss in a variety of neoplasms. Interestingly, many of these lack the typical rhabdoid features ascribed to this group of tumors, making their identification difficult. CASE PRESENTATION: We describe the cytological, histological, immunohistochemical and molecular features of the first case of primary SMARCB1 (INI1)-deficient carcinoma of the thyroid gland in literature. The tumor was unique in various aspects; apart from never having been documented at this location, it showed extensive glandular differentiation, mimicking metastatic adenocarcinoma. CONCLUSION: Awareness of this novel entity is essential to avoid misdiagnosis, and for appropriate management, especially in an era of increased feasibility of targeted therapy.