Atypical fibroxanthoma with dermal amyloid deposit.

Atypical fibroxanthoma (AFX) has been associated with several secondary changes, such as keloidal areas, myxoid or chondroid changes, osteoclast-like giant cells, sclerosis, fibrosis, pigmentation, hyalinization, or hemorrhagic areas. We report a case of an AFX 4 cm in diameter on the forehead of a 77-year-old male patient. There were dermal amyloid deposits intermingled with the tumor fascicles on the periphery of the lesion. A moderate inflammatory chronic lymphoplasmacytic infiltrate was found in the periphery of the tumor. The amyloid deposits were positive with Congo red staining (but negative after permanganate-treatment). The deposit was also immunostained with antibodies against CKs (AE1/AE3 and CK5/6). It did not stain with anti-amyloid A, or with antibodies against either kappa light or lambda light chains. Therefore the amyloid deposit was keratinic in nature.