ADENOMATOUS LESIONS OF THE TEMPORAL BONE IMMUNOHISTOCHEMICAL ANALYSISAND THEORIES OF HISTOGENESIS

Adenomatous lesions of the temporal bone represent a diverse group of neoplasms. At least three histopathologic patterns have been described : glandular; ribbon-like, or ''festooning;'' and aggressive papillary. Combinations of glandular and ribbon-like histologies in the same les ion are not uncommon. The glandular and ribbon-like histologies have b een associated with carcinoid tumors, and the aggressive papillary rum or has been considered a separate entity. Recently, the endolymphatic sac has been proposed as the site of origin of the aggressive papillar y lesions. Previous reports have described neuroendocrine properties w ith characteristics embracing the th ree histologic types. The authors postulate that the neural crest is the site of origin of this un usua l group of neoplasms. Immunohistochemical analysis on the pathologic s pecimens of patients with adenomatous lesions of the temporal bone was performed to test this hypothesis. From 1975 to 1992 seven patients w ere treated at the Cleveland Clinic Foundation with a diagnosis of mid dle ear adenoma. A panel of special stains for neuroectodermal markers , including synaptophysin, chromogranin, neuron specific enolase, calc itonin, and serotonin was used on the paraffin-embedded formalin-fixed specimens. Three lesions were also evaluated by electron microscopy, all demonstrating dense core, intracytoplasmic granules. Three ribbon- like tumors were positive for synaptophysin and chromogranin, and two of these were positive for serotonin. One glandular tumor was positive for synaptophysin, and an aggressive papillary tumor was positive for synaptophysin and neuron specific enolase. An additional papillary tu mor was referred following a third recurrence without accompanying imm unohistochemical data. Cholesteatoma-like material was identified with a few glandular cells interspersed, all negative by immunohistochemic al evaluation. The seventh specimen, initially diagnosed as papillary adenoma on light microscopy, was not studied by the aforementioned sta ins, and was later identified as a papilloma of sinonasal origin. The neural crest gives rise to pluripotential stem cells with widespread a natomic distribution, including the temporal bone. Because immunomarke rs used in this study are specific for neuroectodermal differentiation , results suggest that temporal bone adenomas have neuroendocrine char acteristics and could be derived from the specialized neuroectoderm of the neural crest.