Trichoscopy is a diagnostic tool for hair and scalp diseases. It was recently shown that it also allows the identification of features associated with disorders that typically do not affect the scalp. The aim of this article was to analyse and outline the usefulness of trichoscopy in suspecting such diseases. Connective tissue diseases were the most investigated systemic disorders in regard to trichoscopy. The most common features of systemic lupus erythematosus, systemic sclerosis and dermatomyositis are thick arborizing and tortuous vessels. Avascular areas are present in systemic sclerosis. Spermatozoa-like vessels may be observed in cutaneous T-cell lymphomas, while salmon-coloured areas with arborizing and linear vessels may be seen in patients with cutaneous B-cell lymphomas. In patients with advanced multiple myeloma, follicular spicules may be observed. Trichoscopic features of angiosarcomas include pink areas, red, polymorphic areas and dark red to purple areas. Polymorphous vessels and whitish areas on a pink background are the predominating trichoscopic features of metastases of malignant tumours to the scalp. Cutaneous sarcoidosis is characterized by orange-coloured areas and telangiectasias. Systemic amyloidosis may manifest with salmon-coloured perifollicular halos, while the most common trichoscopic features of syphilitic alopecia are as follows: decreased number of hairs per follicular unit, vellus hairs, background erythema, focal atrichia and yellow dots. In conclusion, dermatologists may suspect some systemic diseases on the basis of trichoscopic findings.
© 2023 European Academy of Dermatology and Venereology.