๐ ็ธฝ็ฎ้ ๏ฝ ๐ ่ฑๆๅๆ๏ผๆฌ็ฏ๏ผ ๏ฝ ๐ ๅฎๆด็ฟป่ญฏ ๏ฝ โญ ็ฒพ่ฏ็ญ่จ
SECONDARY CUTANEOUS AMYLOIDOSIS
Secondary cutaneous amyloidosis refers to amyloid deposits that are inapparent clinically but can be detected histopathologically within skin lesions, most commonly in seborrheic keratoses and basal cell carcinomas and occasionally in dermatofibromas, intradermal melanocytic nevi, pilomatricomas, trichoepitheliomas, sweat gland tumors, Bowen disease, and porokeratosis. In these settings, the amyloid deposits represent a histologic epiphenomenon without obvious clinical implications. Secondary cutaneous amyloidosis has also been reported following PUVA therapy.
Hypotrichosis simplex of the scalp 1/hypotrichosis 2 (HYPT2) is an uncommon autosomal dominant disorder and is perhaps best regarded as a particular form of secondary cutaneous amyloidosis. Patients have normal hair at birth, but progressively lose most scalp hair by the third decade. Eyebrows, beard and axillary hair, nails, and teeth develop normally. Pathogenic variants in the gene that encodes corneodesmosin, a glycoprotein expressed in the epidermis and inner root sheath, lead to truncated corneodesmosin proteins. The latter accumulate as amorphous amyloid deposits around hair follicles and in the papillary dermis.