I see many here comment and seem to think skin biopsies are a final diagnosis-this isn’t the case. For cancer or infection yes they are looking for something truly distinctive that is yes/no. For inflammation of the skin, including eczema, lichen simplex, psoriasis etc no it is absolutely not definitive. Infact there’s entire research papers noting how difficult it is to distinguish them. What’s happening is skin inflammation and that looks nearly identical in all conditions. There are no truly distinct features only things that mildly lean one way or another. For instance; spongiosis is uncommon of psoriasis but not unheard of. Neutrophils in the stratum corneum is common in pso but present in a significant portion of eczema as well. The more chronic eczema gets the more a granular layer reduces and is destroyed. (Which is common in psoriaais) the list goes on.

That’s why if you actually read the report it only even uses words like compatible, not consistent with, it typically also lists all possibilities.

I was initially misdiagnosed with psoriasis even with a biopsy. Then got eczema diagnosis. Biopsy is a useful tool but they aren’t the definitive answer many here seem to imply.