Invasive micropapillary carcinoma (IMC) is generally an aggressive morphologic variant that has been described in the bladder, lung, breast, salivary gland, gastrointestinal tract, and ovary.
Given the morphologic similarities between IMCs arising from different organ systems and the high propensity of this histologic subtype for lymphatic metastasis, it may be necessary to use immunohistochemical (IHC) markers to determine the primary site of an IMC.
References
Immunohistochemical Panel to Identify the Primary Site of Invasive Micropapillary Carcinoma. Lotan TL, Ye H, Melamed J, Wu XR, Shih IM, Epstein JI. Am J Surg Pathol. 2009 Feb 20. PMID: 19238079