Patchy hair loss including bacterial demodex, or ringworm infection, or hormonal diseases such as hypothyroidism and Cushing's disease. These diseases should be ruled out by appropriate testing. Skin biopsy of affected areas shows dysplastic (abnormally shaped) hair follicles which are filled with keratin.
Cushing's disease results from excessive production of cortisol, a hormone normally produced by the adrenal glands. This excessive cortisol production can result from abnormalities in the pituitary gland that cause excessive hormone secretion by the adrenal glands, by tumors within the adrenal glands themselves, or by a combination of these factors.
This disease can look identical to infectious diseases (bacterial, fungal), reactions to foreign material (example: foxtail), or some types of cancer.
Mast cell tumors are a malignant tumor that originate in the dermal layer of the skin. These tumors can arise from any area of the body, and may have a variety of appearances.
Affected skin is reddened, scaly, and may lose hair. With continued sun exposure thickened skin, red bumps, plaques, and nodules develop which may become ulcerated and crusty.
Lesions occur most commonly on the trunk, the legs, the digits (toe), the scrotum, the lips, the anus, and the nose. The lesions are typically ulcerated or cauliflower-like in appearance, bleed easily and are typically solitary.