Words (etymology)

•	when first learning dermatology, there are many long names, and words that sound the same because they contain a common root, and are often confusing

•	it is useful to see these words (and the entities) next to each other, in order to distinguish them from each other

The system by which we name diseases in dermatology is, unfortunately, anything but a "system". Names arose as disease were described throughout history. The names are confusing to someone learning dermatology for several reasons:

2.	there are many misnomers (where the name of the disease tells you something that is actually misleading)

Diseases are named by the person who first described them. That could be a clinician, a pathologist, or even an immunopathologist, or a geneticist. Each could give the same disease a different name, or classify a group of diseases differently by emphasizing different characteristics (pathologic vs. clinical). A good example of the confusion this causes can be the various ways to classify the vasculitides. Another good example of this confusion is the immunobullous diseases:

•	Cicatricial pemphigoid: defined by clinical presentation (predominantly mucosal) (variable antigens)

•	Linear IgA Disease: defined by DIF – (variable antigens and variable clinical presentations)

Now that medicine has advanced, we should probably name all of these immunobullous diseases by their lowest common denominator (the antigen). But "cicatricial pemphigoid" is a clinical way to group these diseases. It is similar to genetics where several genotypes may all lead to one common phenotype.

5. the final problem in dermatology is that we sometimes give names to "physical signs" (e.g. purpura fulminans, lividoid vasculitis, keratoderma blenorrhagicum) and then treat them as diseases unto themselves:

Cardiologists do not consider a systolic murmur to be a diagnosis; wheezing is not a diagnosis; cyanosis is not diagnosis; pitting edema is not a diagnosis. These are all physical signs. Purpura fulminans is not a diagnosis, it is the cutaneous manifestation of DIC. Lipodermatosclerosis and atrophie blanche are not diagnoses unto themselves, but rather a number of physical signs indicating the diagnosis of venous stasis. That is not to say that other underlying conditions cannot cause the same physical sign. A textbook will say that “atrophie blanche is associated with venous stasis, cryoglobulinemia, antiphospholipid syndrome (i.e. hypercoaguable states), vasculitis and vasculopathies etc…” That is like saying that wheezing is associated with asthma, or bronchiolitis or a foreign body in the airway. Atrophie blanche is a physical sign that can be seen in (caused by) these conditions. The pathogenesis being fibrotic scarring secondary to insult, often an ischemic insult, or ulceration.

Pseudopalade of Brocq is not a diagnosis. It is a physical sign, seen at the end stage of a scarring alopecia that is no longer active. Mid-dermal elastolysis is also not a diagnosis. It is a histologic sign. There is no primary process in which macrophages are selectively ingesting the elastin of the mid dermis. There is a primary insult (sun or physical e.g. stretch from weight lifting) and a secondary phagocytosis.

We also like to give numerous names to the same physical sign. “Keratoderma blenorrhagicum” is how we describe the sole of a foot in Reiter’s disease. But we don’t call the exact same lesion by the same name when it is seen in psoriasis. I have no problem with this, as it does not lead to confusion, but is simply a vestige of the specialty. Things in dermatology are visible to the naked eye and were named years before the pathogenesis was elucidated. That is why we have names such as lupus pernio and lupus vulgaris.

•	Urticaria although "chronic idiopathic urticaria", which now has a test and an autoimmune pathogenesis, can be called a "diagnosis"