Rash on a grand scale
Extensive red scaly rashes on the trunk can be many things, but the three commonest diagnoses are psoriasis, eczema and tinea corporis. By simply prescribing a topical steroid cream they will all improve, including the tinea, because the steroid suppresses the body’s immune reaction to the fungus.
However, the fungus just keeps spreading across the stratum corneum and flares again when the steroid cream is withdrawn. Repetition of this cycle leads to an extensive tinea corporis all across the abdomen, as shown in this patient.