Localized amyloidosis of the vulva with and without vulvar intraepithelial neoplasia: report of a series.

Localized primary cutaneous amyloidosis is uncommon in Europe and North America and is infrequently reported in the English literature. The constituents of such deposits have not been previously examined; this series characterizes amyloid deposits in localized vulvar amyloidosis and their association with vulvar intraepithelial neoplasia. All biopsies and excisions of vulva over 18 months were reviewed. Cases with suspected amyloidosis were retrieved after institutional review board approval. Twenty cases mimicking amyloidosis were selected as controls. All study and control cases were stained with Congo red. Four Congo red-positive study cases were studied by liquid chromatography-tandem mass spectrometry. Of 27 Congo red-positive study cases, 25 were then examined by immunohistochemical stains with antibodies to cytokeratin 5 (CK5) and cytokeratin 14 (CK14). Of 149 cases reviewed, 26 localized and 1 systemic vulvar amyloidosis were identified. Liquid chromatography-tandem mass spectrometry analysis of the deposits revealed unique peptide profile consistent with CK5 and CK14. Immunohistochemical staining with antibodies to CK5 and CK14 also detected these components in the deposits. The vulvar deposit of systemic amyloidosis consisted of amyloid light chain (λ)-type amyloid deposit. All control cases were negative for Congo red. Keratin-associated amyloid materials (CK5 and CK14) were found to be unique in localized vulvar amyloidosis. Leakage of keratins from the basal layer of the epithelium into the superficial dermis may have been the possible source of the deposits. It appears to be associated with both high-grade and low-grade vulvar intraepithelial neoplasias and, rarely, lichen sclerosus, seborrheic keratosis, and benign vulvar skin.