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S Brownstein, B Mathew, S Robertson, D Coupal, R Prokopetz, DR Jordan; Immunohistochemical Profile and Histochemical Analysis of Mucoepidermoid Carcinoma of the Conjunctiva . Invest. Ophthalmol. Vis. Sci. 2002;43(13):1088.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: Mucoepidermoid carcinoma of the conjunctiva (MCC) is a variant form of conjunctival squamous cell carcinoma (SCC) which has an extraordinary propensity to invade the eye and orbit. The definitive diagnosis of MCC relies on cytologic features and histochemical evidence of mucin production. We evaluate the immunohistochemical and histochemical profile of MCC to determine which markers and/or stains best differentiate between MCC and conjunctival SCC. Methods: Multiple specimens of MCC (ten from three patients) and conjunctival SCC (nine from nine patients) were stained with the following: periodic acid-Schiff (PAS), PAS with diastase, alcian blue, colloidal iron, Movat's pentachrome, mucicarmine, BRST-1, BRST-2 (GCDFP-15), cytokeratins ae1/ae3, cytokeratins 7 and 20, high and low molecular weight keratin, carcinoembryonic antigen (CEA), epithelial membrane antigen (EMA), Ki-67 antigen (MIB-1), mucin 1, S-100, tenascin, and vimentin. Results: There was positive staining of MCC with the histochemical stains: periodic acid-Schiff (PAS), alcian blue, colloidal iron, and mucicarmine. The most informative immunohistochemical stains were CEA and mucin 1. There was positive staining of MCC with CEA in 8 of 9 cases (89%) and in all the cases with mucin 1 (100%). The staining pattern with mucin 1 in MCC was diffusely intense and cytoplasmic within the mucinous portions of the tumor. Mucicaramine did not stain in any of the specimens of conjunctival SCC, while two specimens of SCC were positive for CEA (22%). Mucin 1 was positive in 7 of 8 cases (88%) of SCC, with a less intense staining pattern than that seen with MCC which was predominantly membranous (plasmalemmal) and involved the intercellular bridges in SCC. Conclusion: Our study demonstrated that although mucicaramine is the most specific stain, mucin 1 and CEA are more sensitive markers for MCC. CEA also has a moderately high specificity, whereas the usefulness of mucin 1 relies on noting the different staining pattern of mucin 1 with SCC and MCC. Therefore, with squamous conjunctival lesions that do not stain with mucicaramine but still have a high suspicion of being a MCC, positive staining for CEA or the presence of an intense diffuse cytoplasmic staining pattern for mucin 1, even in focal portions of the neoplasm, could help differentiate these lesions from conjunctival SCC.
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