Pathology of the Head and Neck

222 N. Gale · A. Cardesa · N. Zidar7Poorly differentiated NEC arises most often in thesupraglottis, but it also occurs in other parts of the larynx.It affects men more frequently than women, mostlybetween 50 and 70 years of age; most patients are heavysmokers. The most common presenting symptoms arehoarseness and dysphagia, frequently associated withpainless enlarged cervical lymph nodes due to metastases.It may be associated with a paraneoplastic syndrome[108, 244].Grossly, PD-NECs are submucosal nodular or polypoidmasses, frequently ulcerated and cannot be distinguishedfrom other laryngeal carcinomas.Microscopically, laryngeal PD-NECs are identicalto their pulmonary counterparts [243]. They are composedof closely packed small cells with hyperchromaticround, oval or spindle nuclei and very scant cytoplasm.Necroses, mitoses, as well as vascular and perineural invasionare frequently present. PD-NEC can also be composedof slightly larger cells with more cytoplasm. Themucosa is often ulcerated, but there is no carcinoma insitu or significant atypia.Immunohistochemically, the tumour cells variablyexpress cytokeratins and neuroendocrine markers, suchas synaptophysin, neuron-specific enolase, chromogranin,S-100 protein and CD56.By electron microscopy, sparse neurosecretory granulesare occasionally found, but they may be absent.In the differential diagnosis, the possibility of a metastasisfrom the lung must be excluded. PD-NEC mustalso not be confused with the basaloid squamous carcinoma,malignant lymphoma, and malignant melanoma.Basaloid squamous carcinoma is composed oflarger cells, contains areas of squamous differentiation,tends to stain for high molecular-weight cytokeratins,and is frequently associated with atypia of theoverlying squamous epithelium. Malignant lymphomascharacteristically express leukocyte common antigenand B- or T-cell markers, which are absent in PD-NEC. Malignant melanoma occasionally consists ofsmall undifferentiated cells, thus resembling PD-NEC,but, in contrast to PD-NEC, it typically expresses S-100protein, melan A and/or HMB45.The clinical course is aggressive, characterised byearly metastases to the regional lymph nodes and distantsites, especially to the lungs, bones and liver. In contrastto lung PD-NEC, laryngeal PD-NEC does not frequentlymetastasise to the brain.Radiation with chemotherapy is the treatment ofchoice. Surgical therapy is not indicated because mostpatients have disseminated disease at presentation. Theprognosis is poor, and the 2- and 5-year survival ratesare 16 and 5% respectively [114, 135].7.7.4 AdenocarcinomaIn spite of rather prominent salivary gland tissue in thesupraglottic and subglottic larynx, laryngeal adenocarcinomais rare, accounting for 1% of all laryngealneoplasms [3, 25, 347]. The majority of laryngeal adenocarcinomasare of the salivary gland type. The mostcommon types are adenoid cystic carcinoma and mucoepidermoidcarcinoma. Rare examples of other types ofadenocarcinoma have been also described in the larynx,such as acinic cell carcinoma [306], clear cell carcinoma[262], malignant myoepithelioma [168], epithelial-myoepithelialcarcinoma [240], salivary duct carcinoma[109], etc.The aetiology is unknown, although exposure to asbestosor lead, alcohol abuse, viral infections, ionisingradiation and genetic risk factors have been implicatedas possible aetiologic factors [221].7.7.4.1 Adenoid Cystic CarcinomaICD-O:8200/3In contrast to other laryngeal carcinomas, adenoidcystic carcinoma (ACC) occurs at a younger age, withno gender predominance, and is more common in thesubglottis [348]. Symptoms are similar to those of othertumours in the same localisation. In addition, pain isfrequently present, probably because of the tendency ofACC towards perineural invasion.Macroscopically, the tumour usually grows as a submucosalmass, covered by normal mucosa.The microscopic features of laryngeal ACC are thesame as in other locations.Laryngeal ACC is characterised by a slowly progressivecourse, with a high incidence of local recurrence,long survival and a low cure rate. ACC has a tendencytowards haematogenic spread, mostly to the lungsand less frequently to the bones, liver and other organs[86, 348]. It does not usually metastasise to the regionallymph nodes.The treatment of choice is complete surgical excision.The 5-year survival rate is 30% [221, 347].7.7.4.2 Mucoepidermoid CarcinomaICD-O:8430/3Mucoepidermoid carcinoma (MEC) occurs at all ages,even in childhood, but it usually presents in the 6th and7th decades, predominantly in males. The majority occursin the supraglottis, but it has also been described inthe glottis and subglottis, as well as in the hypopharynx[221, 335]. The clinical picture correlates with the localisationand size of the tumour.