Invasive carcinoma of no special type (NST) also known as invasive ductal carcinoma or ductal NOS and previously known as invasive ductal carcinoma, not otherwise specified (NOS) is a group of breast cancers that do not have the "specific differentiating features". Those that have these features belong to other types.In this group are: pleomorphic carcinoma, carcinoma with osteoclast-like stromal giant cells, carcinoma with choriocarcinomatous features, and carcinoma with melanotic features. [Source: Wikipedia 
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