Diagnosis and Comments:
The electron microscopy established a diagnosis of pleomorphic
adenoma. The redundant basal lamina and excessive production
of glycosaminoglycans and elastic fibers by the neoplastic myoepithelial
(nonluminal) cells is charactersitic. The commonest groups of
neoplasms occurring in the parapharyngeal space are of salivary
gland and neural origin (Fig. 7). Of these, the majority are pleomorphic
adenomas in the former group and schwannomas in the latter. Based
on the ultrastructural findings, the proposed radical surgery
to resect what was originally thought to be a malignant tumor
was canceled and the patient discharged to be followed by her
family physician.
Three months later, the mass had increased somewhat in size. Using a more conventional, less destructive approach, a total parotidectomy and resection of the tumor mass (Fig. 8) in the parapharyngeal space was performed. Histologically, areas of typical pleomorphic adenoma were present (Fig. 9) along with more cellular regions (Fig. 10) of the type that made up the original biopsy specimen. When the latter growth pattern predominates, the tumor is referred to as a cellular pleomorphic adenoma. The cellularity coupled with the biphasic nature of the neoplasm led to the reasonable suggestion of biphasic synovial sarcoma, a tumor that can occur in the pharyngeal region.
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| Figure 7. Principal diagnostic considerations in tumors of the paraphyaryngeal space. | Figure 8. Gross photograph of the resected tumor. Note the rather glassy appearance of some areas of the cut surface reflecting the myxoid and chondromyxoid regions of a pleomorphic adenoma. |
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| Figure 9. Typical biphasic growth pattern of a pleomorphic adenoma with many glandular lumens surrounded by "stroma". The latter has nonluminal cells loosely organized within myxoid material or variably separated by fibrous (collagenous) tissue. | Figure 10. Another area of this tumor with less extracellular "stromal" materials, creating a cellular region within which are a number of glandular lumens. |
