Necrotizing sialometaplasia versus invasive carcinoma of the head and neck: the use of myoepithelial markers and keratin subtypes as an adjunct to diagnosis.
OBJECTIVE
To investigate the use of immunohistochemistry in distinguishing necrotizing sialometaplasia (NSM) from squamous cell (SCC) and mucoepidermoid carcinoma (MEC) by (i) the identification of myoepithelial cells and (ii) cytokeratin (CK) expression.


RESULTS
Thirteen cases with the histological changes of NSM, eight SCCs and eight MECs were examined with the following immunohistochemical markers: calponin, S100, smooth muscle actin (SMA), p63, CK7, CK5, CK6 and CAM5.2. The distribution and intensity of staining were recorded. Residual myoepithelial cells (best demonstrated by calponin and SMA) were identified at the periphery of the epithelial islands in all cases of NSM (although not in all islands), in contrast to MEC and SCC. S100 showed a similar pattern, although staining fewer cells. Moderate rather than extensive expression of CK7 may help to distinguish NSM from MEC.


CONCLUSIONS
Identification of myoepithelial cells and CK7 expression may help to distinguish NSM from its mimics.
Rizkalla
H
H
Department of Histopathology, St James's Hospital, Dublin, Ireland.
Toner
M
M
D000199:Actins / Q000378:metabolism; D015415:Biomarkers / Q000378:metabolism; D014408:Biomarkers, Tumor / Q000378:metabolism; D002135:Calcium-Binding Proteins / Q000378:metabolism; D018277:Carcinoma, Mucoepidermoid / Q000175:diagnosis / Q000378:metabolism / Q000473:pathology; D002294:Carcinoma, Squamous Cell / Q000175:diagnosis / Q000378:metabolism / Q000473:pathology; D003937:Diagnosis, Differential; D006258:Head and Neck Neoplasms / Q000175:diagnosis* / Q000378:metabolism* / Q000473:pathology; D006801:Humans; D007150:Immunohistochemistry; D007633:Keratins / Q000378:metabolism; D053531:Keratins, Type II / Q000145:classification / Q000378:metabolism*; D008565:Membrane Proteins / Q000378:metabolism; D008840:Microfilament Proteins / Q000378:metabolism; D009418:S100 Proteins / Q000378:metabolism; D012797:Sialometaplasia, Necrotizing / Q000175:diagnosis* / Q000378:metabolism* / Q000473:pathology; D000096985:Calponins
D000199:Actins; D015415:Biomarkers; D014408:Biomarkers, Tumor; D002135:Calcium-Binding Proteins; D007633:Keratins; D053531:Keratins, Type II; D008565:Membrane Proteins; D008840:Microfilament Proteins; D009418:S100 Proteins; D000096985:Calponins; C400901:CAM 5.2 antigen; C081876:CKAP4 protein, human