Page 116 - The Netter Collection of Medical Illustrations - Integumentary System_ Volume 4 ( PDFDrive )

Plate 4-31 Integumentary System

FIXED DRUG ERUPTION
Lichenoid-appearing
purplish macule or
Fixed drug eruptions are responsible for up to 20% of plaque. Fixed drug
all cutaneous drug eruptions. They can occur anywhere eruptions often occur
on the body and have been reported to occur in reaction at the same location
to a long list of medications. There are a few medicines on future exposure
in particular that have been associated with fixed drug to the causative agent.
eruptions. One of the most frequent causes in the past
was phenolphthalein contained in over-the-counter
laxatives. After the numerous side effects from this
medication were revealed, it was withdrawn from the
market and is now of only historical significance. Fixed
drug eruptions are unique in many ways, both clinically
and histologically. The exact pathogenesis is unknown.
Clinical Findings: Clinically, fixed drug eruptions
appear as oval to round, dusky red to purple macules
with minimal surface change. Some cases have shown The glans penis is one of the most frequently
bullous-type reactions. The fixed drug eruption is involved areas in fixed drug eruptions.
unique in that it recurs in the same location time and
time again as the patient is reexposed to the offending
agent. Sometimes months may pass between exposures,
and yet the reaction recurs in the same location. The
glans penis, the oral mucosa, and the hands are the most
commonly involved areas, although any area of the skin
may be involved. Most cases show one area of reaction,
but some have more than one. It is unusual to have
more than five areas of involvement, but case reports of
widespread involvement have been reported. In these
cases, the differential diagnosis includes erythema
multiforme. Another characteristic feature is the postin-
flammatory hyperpigmentation that occurs after resolu-
tion. This is caused by the vast amount of pigment
incontinence that results from disruption of the dermal-
epidermal junction. This hyperpigmentation can take
months to years to resolve.
The list of medications that can cause fixed drug erup-
tions continues to grow. The most frequently reported
culprits are the sulfa-based antibiotics, nonsteroidal
antiinflammatory medications, and tetracycline-based
antibiotics. Common over-the-counter medications
have also been reported to cause fixed drug eruptions,
including acetaminophen and herbal supplements. For
this reason, a thorough history that includes both pre-
scription and other medications is required.
Histology: Fixed drug eruptions are categorized in Fixed drug eruption (H&E stain) exhibiting a lymphocytic lichenoid
the lichenoid pattern of histological skin disease. These infiltrate with pigmentary incontinence. Some vacuolar alteration
drug reactions show a prominent lichenoid infiltrate may be seen scattered about the epidermal-dermal interface.
with lymphocytes. The infiltrate is associated with very Apoptotic keratinocytes can be variable in number.
noticeable vacuolar change of the basilar layer of the
epidermis and prominent formation of necrotic kerati-
nocytes (Civatte bodies). There is melanin incontinence
within the dermis in all cases, and this can be used to
differentiate fixed drug eruption from other lichenoid within the inflammatory infiltrate. This abnormal agent. Once this is done, the lesions heal within a
reactions. The bullae form within the subepidermal immune response is responsible for the tissue damage. month. Medium to potent topical corticosteroids
space in the bullous variant of fixed drug eruption. Rare The precise interaction and mechanism by which can be used to help relieve pruritus and potentially
variants of fixed drug eruption have been described that certain medications react with the immune system of speed healing. Fixed drug eruptions often leave an area
have included evidence of vasculitis. This form is susceptible individuals to cause fixed drug eruptions has of postinflammatory hyperpigmentation or hypopig-
exceedingly rare. not been elucidated. mentation after the initial reaction has resolved.
Pathogenesis: The etiology is unknown. Research has Treatment: The main point in therapy is making This pigmentary abnormality can last for months
indicated that CD8+ T cells are the primary cell type the correct diagnosis and removing the offending to years.

102 THE NETTER COLLECTION OF MEDICAL ILLUSTRATIONS