Morphological Patterns and Immunohistochemical Characteristics of Metaplastic Carcinoma Breast: A Six Year Analysis in a Tertiary Care Hospital

Abstract

Introduction: Carcinoma breast is a leading cause of morbidity and mortality in females. Metaplastic Carcinoma Breast (MCB) accounts for less than 1% of invasive breast carcinomas. This variant has an aggressive behaviour and hence poor prognosis. Since metaplastic carcinomas are rare and most patients succumb within a short span of time, detailed studies are required in this area. Moreover, being a heterogeneous group, sub classification and prediction of biologic behaviour of metaplastic carcinomas is challenging. World Health Organization (WHO) classification and recent studies show the importance of identifying the subtypes of MCB based on histopathology. Aim: To analyse the histopathological patterns and expression of Immunohistochemical (IHC) markers in MCB. Materials and Methods: All cases of MCB diagnosed in Pathology Department of our Institute during the period of six years from January 2011 to December 2016 were analysed. Age distribution, histopathological and IHC patterns were studied using the registers, histopathology slides and IHC slides in the department. The data collected were analysed using SPSS software 16.0. Results: A total of 36 cases of MCB accounting for 2.6% of breast carcinomas (n=36, total number of invasive breast carcinomas=1405) were received in our Institution, which is a tertiary care centre. Age distribution ranged between 34 to 72 years. All except one were female patients. Predominant histopathological pattern was malignant spindle cells accounting for 53% cases. Seventeen percent showed predominant squamous areas. Other types were heterologous differentiation (chondroid/osseous) in 11%, mixed pattern (squamous areas+invasive ca NST(No Special Type) in 11%, choriocarcinomatous component in 3%, fibromatosis like in 3% and low grade adenosquamous type in 3%. Lymph node metastasis was present in 41.4% (n=12) and 69.2% of cases showed triple negative pattern in immunohistochemistry. Conclusion: Majority of metaplastic carcinomas was solid grey white growths with infiltrative margins but cystic degeneration (in 24.1% cases) was associated with squamous areas. Presence of epithelial elements confers an increased chance of nodal spread and sarcomatous elements confers increased risk of extra nodal dissemination, hence this should be highlighted in the report stressing the need for a more aggressive follow up of those with sarcomatous component. The results of this study were comparable with other similar studies.

Keywords

• carcinosarcoma
• histopathology
• triple negative