Pathology of the Head and Neck

278 M. A Luna · K. Pineda-Daboin9Metastatic spindle cell neoplasms most likely representsarcomatoid carcinomas, melanomas and sarcomas,especially rhabdomyosarcomas. Pankeratin, MART-1, HMB-45, S-100 protein, desmin, smooth muscle actinand myogenin are some immunostains that help todistinguish these neoplasms [29]. Primary spindle celllesions arising in lymph nodes, such as Kaposi’s sarcoma,presumed tumours of the reticulum cell lineage andbenign intranodal myofibroblastomas, must be distinguishedfrom metastatic spindle neoplasms [2, 56].Undifferentiated malignant neoplasms in cervicallymph nodes need to be investigated with immunohistochemicalstudies. CK-positive malignancies with themorphology of the nasopharyngeal type of carcinomas(NPC) are usually located in the posterior neck, whereasmetastasis from undifferentiated sinonasal carcinomas(SNUC) are present in the upper and mid-cervical regions.If the metastases are located in the lower neck, thelung is the most likely source. If the carcinomas in additionexhibited neuroendocrine differentiation, Merkelcell carcinoma or small cell neuroendocrine carcinoma,from either the lung or the larynx, is the best diagnosis.Merkel cell carcinomas are CK 20-positive [19] and pulmonarysmall cell carcinomas are CK 20-negative andTTF-1 positive in 83–100% of cases [83]. Benign nevuscells have been found in the capsules of submandibularlymph nodes. This rare finding should not lead to an erroneousdiagnosis of malignancy [54].Paccioni et al. evaluated 25 cases of occult metastasisto cervical lymph nodes for the presence of Epstein-Barr virus (EBV) by in situ hybridisation following fineneedleaspiration biopsies of the neck mass and correlatedthe findings with the histologic types of the surgicalspecimens (after locating the primary site of origin).These authors reported that EBV was expressed in 7 metastases,ultimately proving their origin from the nasopharynx,while the remaining 18 cases (not of Waldeyer’sring origin) were negative for EBV [84]. The authorsindicated that detection of EBV in cervical metastasesmay assist in the localisation of the occult primary toWaldeyer’s ring. SNUC do not express EBV [84].The pattern of CK expression is significantly differentin SNUC and NPC, which could be of diagnosticaid. Franchi et al. demonstrated that SNUC expressCK 8 in 100% of cases and CK 19 and CK 7 in 50%, andare negative for CK 5/6, while NPC express CK 5/6 andCK 13 in 90% of cases and are negative for CK 7 [40].Metastases from melanoma, rhabdomyosarcoma,and rarely from olfactory neuroblastoma should beconsidered with the CK-negative undifferentiated neoplasmsand proper immunohistochemical markers investigated(Fig. 9.15). In CK-negative tumours, the possibilityof malignant lymphoma should be consideredand CD 20, CD 3 and antibodies for leukocyte commonantigen should be measured [29].Fig. 9.15. Metastatic spindle cell melanoma in a cervical lymphnode9.6.7 Treatment and ResultsFactors that affect survival in patients with metastasisfrom an unknown primary tumour are clinical stageof the neck, extranodal extension of metastasis and thepresence of recurrent or residual disease after treatment.Surgery combined with irradiation has resultedin better local control of the disease than either therapyalone [53]. The 5-year survival results in series ofpatients with SCC metastatic to the neck from an unknownprimary origin range from 0 to 54% [45, 64, 72,75]. In the last series from the University of Texas M.D.Anderson Cancer Center, the 5-year actuarial survivalrate was 55% [123].9.7 Neck Dissection9.7.1 Classificationof Neck DissectionsThe American Academy of Otolaryngology-Head andNeck Surgery and the American Society of Head andNeck Surgery classified neck dissection into four categories:radical, modified radical, extended and selective[99].Neck dissection is classified primarily by the cervicallymph node groups that are removed, and secondarilyon the anatomic structures that may be preserved, suchas the spinal accessory nerve, the sternocleidomastoidmuscle, and the internal jugular vein [71, 99].The cervical lymph node groups are referred to usingthe level system as described by the Sloan-Kettering MemorialHospital Group (Fig. 9.1). Definition of the anatomicboundaries of the different lymph node groupsis beyond the scope of this chapter and can be found inother sources [99, 110].