Small rice grains under the scrotum can be determined by dermatoscopy, clinical symptoms and so on whether it is eczema or fungal infection. 1. Dandruff microscopy: you can take the local skin dandruff for microscopic examination, if you find fungal spores, mycelium, etc. can be determined to be a fungal infection; if there is no spores, mycelium, etc., consider that it belongs to eczema. 2. Clinical symptoms: acute eczema will cause skin erythema, small papules, severe blisters, and there is a tendency to erosion and oozing; chronic eczema will cause dark red skin, skin thickening, the surface of the rough mossy changes. Eczema lesions are often symmetrically distributed, and the lesions are polymorphic. Symptoms of fungal infection may appear as red papules, small blisters, followed by red patches and clear boundaries, with the edges constantly expanding outward to form a ring-shaped erythema surrounded by small papules. Small rice grains under the scrotum, it is recommended to promptly go to the hospital for further examination, under the guidance of the doctor to determine whether it is eczema or fungal infection.