Localised cutaneous Amyloidosis Revealed by Immunohistochemistry: an Interesting Diagnostic Tool

A 85-year-old woman had a lightly pruritic firm plaque on the forearm for 28 years. She had no major medical trouble and she didn’t receive any medical treatment before visiting dermatology’s department. Biopsy specimen from the lesion revealed an amorphous a cellular eosinophilic deposits (black star) in the papillary dermis (Figure 1 A and B). The overlying epidermis was of normal thickness without hyperkeratosis (Figure 1 A and B). The deposits were negative for Congo red staining (Figure 1C), without typical green birefrengence on polarizing microscopy (Figure 1D). On immunohistochemistry, they stained diffusely positive with pan cytokeratin AE1/AE3