When a Rash is Not a Rash
day thousands of people go to their practitioner's offices, walk-in clinics and
emergency rooms complaining of a "rash". Some of them itch, some of them don't.
Some have been present for a few days, some for many years. Some come and go
sporadically without warning, some present acutely, some appear like clockwork
at specific times of the year or after exposure to specific irritants.
of these conditions are either related to exposure to an allergy or irritant or
are in the atopic dermatitis spectrum. Most practitioners can recognize and
distinguish the urticarias and things such as scabies relatively easily and
treat them appropriately. For the majority of patients, many exanthems will
resolve without treatment; for those that don't, a topical steroidal cream or
ointment will resolve or improve them.
Sometimes though, something that appears to be a rash is
only a cutaneous manifestation of something that has the potential to be
significantly more ominous. One such example of this is mycosis fungoides or
cutaneous T-cell lymphoma. This form of lymphoma can look exactly like an
atopic dermatitis and have the same symptomology (redness, pruritis, sporadic
and transient). The difference is that
this condition, if it advances, can be lethal.
So, how can you tell the difference if they all look the
same? In a word, BIOPSY! If an elderly person presents to your clinic with
complaints of a long standing rash, treated for multiple years with minimal
success with topical steroids and the erythema seems to be confined to
photo-protected areas of the body, or those covered with clothing, take a
It is unlikely that
atopic dermatitis will acutely begin in the fifth or sixth decades of life with
no previous history. It also usually presents on the antecubital and posterior
knees. Mycosis fungoides usually presents in the fifth or sixth decades of life
and ultraviolet light suppresses rash. Therefore, the exposed areas of skin are
spared and as mentioned earlier, the trunk or covered regions of the skin are
the most common sites of presentation.
If you take a biopsy and it is consistent with mycosis
fungoides, don't panic. Refer them to hematology/oncology for evaluation and
management. The majority of cases do not progress to the more dangerous stages
and can be controlled with topical steroids and ultraviolet treatments. I would
advise anyone who sees a person with rashes on the body that appear in the sun
covered regions to keep this disease in mind and familiarize themselves with