Head and neck amyloidosis: clinicopathological features and immunohistochemical analysis of 14 cases.

BACKGROUND: Amyloidosis is associated with or caused by amyloid deposition. These fibrillar proteins may be deposited extracellularly causing tissue damage or impairment.
OBJECTIVES: The aim of the study was to retrospectively review pathology archives in two oral diagnostic centers for cases fulfilling criteria of amyloidosis and to differentiate AA and AL types of amyloidosis.
METHODS: The clinicopathological features, alkaline Congo red staining, with and without pretreatment with potassium permanganate, and immunohistochemical (IHC) staining with anti-AA, anti-kappa (κ), and anti-lambda (λ) light chain antibodies were carried out and analyzed.
RESULTS: The search identified 14 cases. Ten patients were women and four were men, with a mean age of 58 years. Eleven patients had systemic involvement by amyloidosis (associated either with multiple myeloma or plasma cell dyscrasia/monoclonal gammopathies), while three presented the localized type, one of them associated with plasmacytoma. All cases showed positivity for κ or λ light chains (AL-amyloid) and presented resistance to the potassium permanganate pretreatment.
CONCLUSIONS: Our results show that the head and neck region is preferentially affected by systemic AL-amyloidosis, usually associated with plasma cell dyscrasia. Interestingly, two cases affected by inflammatory rheumatic diseases presented AL-amyloid deposition. Moreover, even after pretreatment with potassium permanganate, which was helpful in highlighting the presence of AL-amyloid, in agreement with the IHC findings, clinical classifications should be carefully made in systemic amyloidosis.