Pathology of the Head and Neck

150 S. Di Palma · R.H.W. Simpson · A. Skalova · I. Leivo5Fig. 5.38. Cribriform adenocarcinoma of the tongue (CAT). Avaguely nodular growth pattern is composed of solid nests withtubular structuresFig. 5.39. Epithelial myoepithelial carcinoma (EMCa): characteristicbiphasic appearance with an inner layer of ductal cells andouter layer of clear myoepithelial cells. Basal membrane-like materialsurrounds the outer cellsvours PA, but it is sometimes not possible to distinguishthese tumours, particularly on a small biopsy. Papillarystructures form part of the spectrum of growth patternsseen in PLGA [206], but when extensive, there isevidence that these tumours are slightly but significantlymore aggressive [63, 64], although they do not seemto affect long-term survival. Genuine high-grade malignancycan occur rarely, as either a poorly differentiatedPLGA or as a salivary duct carcinoma [191].5.9.4.1 Cribriform Adenocarcinomaof the TongueICD-O:8525/3A newly described tumour [134] found so far only in thetongue, shares some histological features with PLGA,to which it is probably related. Cribriform adenocarcinomaof the tongue (CAT) usually arises in adults witha mean age of 50 years and equal sex incidence in theroot of the tongue. Generally, at the time of diagnosisthere are metastases in the neck lymph nodes, eitherunilaterally or bilaterally, but distant spread has notbeen described.Microscopic examination shows lobules divided byfibrous septa, composed of areas with solid and microcysticgrowth patterns. In the solid areas, tumour nestsoften display a well-developed hyperchromatic outerlayer with a perpendicular arrangement of cells. Thislayer is frequently detached, forming papillae or glomeruloidstructures surrounded by apparent clefts. The microcysticgrowth pattern is composed of lobules of neoplasticcells with a cribriform and/or tubular architecture,the two patterns often intermingling. Typically, thetubules are approximately of the same size and consist ofone cell layer. Cytologically, there is one cell type; characteristically,the nuclei, which often overlap one another,are pale and vesicular with a “ground glass” quality,thus resembling those of papillary thyroid carcinoma(Fig. 5.38).Each nucleus can contain up to three nucleoli of varyingconspicuousness. Immunohistochemically, a strongor patchy reaction is seen with cytokeratins and S-100protein. Actin, calponin and smooth muscle myosinheavy chain react with only a few areas. They are completelynegative for thyroglobulin.Patients treated with surgical excision and subsequentirradiation have a good chance of prolonged survivalwithout recurrence or further metastatic spread[134].5.9.5 Epithelial-MyoepithelialCarcinomaICD-O:8562/3The mean age at diagnosis of epithelial-myoepithelialcarcinoma (EMCa) is 60 years (range 8–103), with asmall majority in females [62]. It occurs predominantlyin the parotid gland, less often in the submandibulargland, occasionally in minor salivary glands and rarelyin the bronchus [234]. The microscopic appearanceis characterised by small ductular lumina lined withtwo layers of cells (Fig. 5.39). The inner comprises cytokeratin-positiveepithelial cells, and it is surroundedby an outer mantle of often clear myoepithelial cells,which express SMA, smooth muscle myosin heavychain and calponin. S-100 protein also stains the outercells strongly, but is less specific and sometimes reactswith the inner layer [114] – CK 14 appears to be un-