Extramedullary plasmacytoma of the parotid gland. Report of a case with extensive amyloid deposition masking the cytologic and histopathologic picture.

BACKGROUND

Extramedullary plasmacytomas are uncommon. Although approximately 90% occur in the head and neck region, parotid gland localization is extremely rare.

CASE: This report describes fine needle aspiration and histopathologic findings in an extramedullary plasmacytoma arising in the left parotid gland of a 62-year-old man. Aspiration smears showed multiple amorphous clumps of material admixed with ductal epithelial cells, multinucleated giant cells and inflammatory cells rich in plasma cells, suggestive of pleomorphic adenoma. In surgical material, excessive amyloid deposition was observed. Six months later the tumor recurred, and in the second surgical specimen clusters of atypical plasma cells among amyloid deposits was noted. Clinical and laboratory examination excluded multiple myeloma. After local recurrence, radiotherapy was applied. Ten months later the patient was well and without systemic involvement.

CONCLUSION

Two points are important. First, in the salivary gland region, because of the focal metachromasia of amyloid with Giemsa stain, amyloid can be confused with the chondromyxoid matrix of pleomorphic adenoma. Second, although localized forms of amyloid tumor exist, one should keep in mind that amyloid may be so abundant that it may mask an underlying plasma cell neoplasm, as in our case.