Pathology of the Head and Neck

Larynx and Hypopharynx Chapter 7 217Cytoplasmic granula are PAS-positive and resistant todigestion. Marked desmoplasia is often present in olderlesions, thereby masking the presence of granularcells. In about 50–60% of cases, the covering epitheliumshows pseudoepitheliomatous hyperplasia of the overlyingsquamous epithelium [190]. This curious histologicalfeature mimicking infiltrative growth of islands ofsquamous epithelium may lead to the lesion being mistakenfor a squamous cell carcinoma. However, the coexistenceof GCT and true squamous cell laryngeal carcinomahas also been reported [206].Immunohistochemical positivity for S-100 protein,vimentin, CD-68 and neuron-specific enolase, and negativityfor keratin is in accordance with the proposedtheory [49, 198, 232]. It is also confirmed by electronmicroscopic examination; the cytoplasmic granula werefound to be lysosomal structures that contain infoldingsof cell membranes similar to those in Schwann cells[245].Differential diagnosis should include benign lesionssuch as rhabdomyoma, paraganglioma or histiocyticproliferations. In contrast to GCT, rhabdomyoma doesnot show infiltrative growth, its cells are larger withwell-defined cellular borders and evidence of cross-striation.Paraganglioma typically shows an organoid pattern(i.e., Zellballen) and positivity for neuroendocrinemarkers. Proliferation of histiocytes is usually related toinflammatory reaction. Sheets of histiocytes are characteristicallyintermingled with inflammatory cells notcommonly found in GCT. Covering pseudoepitheliomatoushyperplasia of the GCT may lead to incorrect diagnosisof squamous cell carcinoma. An identificationof the underlying granular cells may resolve this sometimesdifficult diagnostic problem.Complete surgical excision, with an attempt to preservethe normal structures, is the treatment of choice[371].but the tumours may also be asymptomatic. Computerisedtomography is a method of choice for radiologicalevaluation [324].Histologically, chondromas show a characteristicwell-defined lobular pattern with benign looking andevenly distributed chondrocytes that lack nuclear pleomorphismand mitotic activity. The cellularity is judgedto be low, when a given high power (×40) field is unlikelyto contain more than 40 nuclei of chondrocytes[83, 209].Pathologic diagnosis of laryngeal chondroma, especiallyfrom a small biopsy specimen, should be reportedwith due reservation. A misleading chondroma-likearea may present in a well-differentiated caseof a chondrosarcoma [26]. It has become apparent thatmany of the so-called chondromas from the past thatrecurred locally were actually misdiagnosed as lowgradechondrosarcomas [83]. It is obvious that the distinctionbetween chondroma and low-grade chondrosarcomaremains a very difficult task. Increased cellularity,nuclear pleomorphism and hyperchromasia, andthe appearance of clusters of malignant-looking chondrocytesin a single lacuna, are the most conspicuoushistological features of chondrosarcoma. A thoroughexamination of the entire specimen is suggested, tryingto avoid an incorrect diagnosis of a given tumour.Chondromas should also be distinguished from laryngealchondrometaplasia, which appears as small nodulesof the fibroelastic cartilage in the submucosal tissueof the glottic region [112].Local conservative excision is preferred for treatmentof laryngeal chondromas. Each recurrence of thelesion should be considered a low-grade chondrosarcoma[358].7.7 Malignant Neoplasms7.6.6 ChondromaICD-O:9220/0Chondromas of the larynx are exceedingly uncommon,well-circumscribed, small (less than 2 cm) cartilaginoustumours that most commonly originate from the posteriorlamina of the cricoid (70–78%) and thyroid cartilage(15–20%) [26, 57, 83, 209, 324, 358], and exceptionallyfrom the epiglottis [166, 209]. They are morecommon in men than in women, the peak incidence rateis in the fifth decade [57]. The development of chondromasin the older population is probably related to thealteration of the ossification process, which starts in thecricoid and thyroid cartilages in the third decade, andincreases with advanced years [358]. Hoarseness, dyspnoea,dysphagia are the usual complaints of patients,7.7.1 Potentially Malignant(Precancerous) LesionsPotentially malignant (precancerous) lesions are histologicallydefined as alterations of the squamous epitheliumfrom which invasive SCC develops more often thanfrom other epithelial lesions [127, 177, 215]. Differentgrades of epithelial lesions that appear during the multistepprocess of carcinogenesis can easily be identifiedhistologically. They are cumulatively called squamousintraepithelial lesions of the larynx (SILs) and representa wide spectrum of histomorphologic changes, rangingfrom benign, reactive lesions, to potentially malignant(risky epithelium) and intraepithelial carcinoma. SILsare discussed in detail in Chap. 1.