The common causes of brown patches with hard scabs include ichthyosis, psoriasis, seborrheic keratosis, and so on.
1. Ichthyosis: this disease is mainly caused by heredity, systemic diseases, drugs and other factors, manifested as dry, flaky skin, like fish scales, often aggravated in winter, reduced in summer, keratinous plaques appeared on the surface of the skin, some rare types of ichthyosis can appear redness of the skin, vesiculation, blisters, etc., blisters rupture can be hard scabs on the brown plaques and other symptoms.
2. Psoriasis: the cause of this disease is not completely clear, may be related to immune factors, genetic factors, etc., manifested as repeated episodes of scaly erythema, papules, plaques, skin roughness, dryness, accompanied by itching, if the patient scratches the lesions bleed, there may be scabs on the brownish-red plaques and other symptoms.
3. Seborrheic keratosis: the etiology and mechanism of this disease is not clear, may be related to skin aging, heredity, sun exposure, air pollution, infection and other factors, manifested as light brown patches of skin, elevated flat papules or plaques, late lesions with oily thick scabs, scaly scabs and other symptoms.
It is recommended that patients according to their own situation, to the regular hospital dermatology consultation, clear causes, reasonable treatment.