Invisible dermatoses: clues and pitfalls to diagnosis

The phrase “invisible dermatoses” has been used in two different contexts: 1) Invisible dermatoses to the clinician, i.e., skin diseases with no significant clinical features, 2) invisible dermatoses to the pathologist, i.e., clinical evident skin diseases that show subtle or hidden histological features resembling normal skin. The list of such diseases, originally comprising only few entities, has been gradually expanded over decades and now is a large one. This paper will focus on entities that fall into this category of subtle or “invisible” dermatoses histopathologically and offers to the dermatopathologist a strategy for their diagnosis, based mainly on proper awareness, recognition of subtle features, liberal use of special stains, immunofluorescence and immunohistochemistry and proper clinicopathologic correlation. The presentation of a series of “invisible dermatoses” will hopefully familiarize the reader with the diagnostic problems and pitfalls associated with and unique to the interpretation of biopsies from this category of dermatoses.