Final Diagnosis -- Carcinosarcoma




Several entities were considered in the differential diagnosis, including metaplastic carcinoma, malignant phylloides tumor and malignant adenomyoepithelioma. Metaplastic carcinoma would be unlikely, given the absence of cytokeratin reactivity in the stromal component. However, metaplastic carcinomas are variable in cytokeratin reactivity and require a panel of markers to rule out this neoplasia.

The relatively even distribution of the glandular and stromal component favors the diagnosis of malignant phylloides tumor, but the glandular architecture was not " phylloides-like". The positivity for vimentin in both component suggests but does not prove common histogensis for the glandular and mesenchymal elements.

Absence of myosin reactivity and intact adenomyoepithelioma growth patten where myoepithelial cells encircle glands make a diagnosis of malignant adenomyoepithelioma less likely. Hence, a diagnosis of carcinosarcoma or high grade malignant phylloides tumor with high grade mammary carcinoma was made.

Carcinosarcoma are biphasic malignant tumor where both epithelial and mesenchymal elements orginate from a single totipotent stem cell.


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Contributed by Deepak Mohan, MD and Dilip Gupta, MD, MIAC

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