Adenosquamous variant of metaplastic carcinoma of breast - an unusual histological variant

Metaplastic carcinoma of breast refers to a heterogeneous group of neoplasms characterized by intimate admixture of adenocarcinoma with dominant areas of spindle cell, squamous cell and/ or mesenchymal differentiation. They constitute the rarest histological variant of invasive ductal carcinoma. These carcinomas have aggressive clinical behaviour and show suboptimal response to standard treatment. A 49-year-old female presented with lump in the left breast for one year. She was diagnosed as infiltrating ductal carcinoma breast with triple negative hormone status by trucut biopsy. She completed four cycles of neoadjuvant chemotherapy. Postchemotherapy, axillary nodes decreased in size but the size of the primary tumour remained the same. Hence, she underwent modified radical mastectomy and the specimen sent for histopathological examination. Grossly, there was a solitary cyst measuring 4x3cm. Histologically, cyst enclosing malignant cells which resemble mature squamous epithelial cells. Also, seen are malignant cells in glandular pattern.