Page 120 - The Netter Collection of Medical Illustrations - Integumentary System_ Volume 4 ( PDFDrive )

Plate 4-35 Integumentary System

GRANULOMA ANNULARE

Granuloma annulare is a commonly encountered rash.
The etiology of this rash is unknown. There are various Annulare dermal pink plaque.
clinical presentations, including localized, generalized, Typically asymptomatic and
subcutaneous, actinic, and perforating forms. The gen- undergoes spontaneous resolution
eralized version has been seen in association with dia-
betes. Most cases spontaneously resolve. Multiple
treatment strategies exist.
Clinical Findings: Granuloma annulare is a rash that
occurs commonly in children but can be seen in any
age group. There is no race predilection, but it is twice
as common in females as in males. The localized form
of granuloma annulare typically starts insidiously as a
small, flesh-colored to slightly yellow papule that
expands centrifugally. Once the lesion gets to a certain
size, its characteristic appearance becomes evident.
Fully formed, the area appears as an annular plaque
with minimal to no surface change. The plaque appears
to have a raised rim around the edge, and the central Generalized
portion of the lesion is almost normal in appearance. granuloma
The peripheral rim is slightly yellow in color. The annulare
lesions can be entirely flesh colored. Patients experi- in a child
ence minimal symptoms. Slight itching may be present.
It is not uncommon to have multiple areas of involve-
ment. The dorsal aspects of the feet and hands are
common locations for this rash. Some patients relate
that their rash is improved during the summer months.
The lesions can range from small papules a few milli-
meters in diameter to larger plaques a few centimeters
in diameter. If only small papules exist, a biopsy is
required for diagnosis. The clinical appearance of the
larger plaques is so characteristic that the diagnosis can
be made clinically.
The generalized version of granuloma annulare con-
sists of numerous widespread papules and small plaques.
In most cases, there are no annulare-appearing plaques;
the diagnosis is considered clinically, but a biopsy is Localized granuloma annulare
required to confirm the diagnosis. This form occurs
almost exclusively in adults and may be seen in associa-
tion with diabetes. Patients with a diagnosis of gener-
alized granuloma annulare should be screened for
diabetes. The other variants of granuloma annulare are
uncommonly encountered. They include the subcuta-
neous form, the perforating variant, and the actinic
variant. The actinic variant may be considered a unique
entity, termed annular elastolytic giant cell granuloma.
Subcutaneous granuloma annulare manifests as deep-
seated nodules within the dermis. A diagnosis is made
via biopsy. This variant appears to be more common in
children. The perforating variant is the rarest form and
is the only variant to exhibit surface change. The areas
of involvement develop small erosions. This is reported
to occur most commonly on the dorsal surface of
the hands.
Pathogenesis: The etiology is unknown. It has been
theorized to represent an abnormal immune response Low power. Granulomatous inflammation through- High power. Necrobiotic collagen within the gran-
to a foreign antigen such as a virus or bacteria. This has out the specimen with necrobiotic collagen bundles ulomatous region
not been proven, and many other theories of pathogen-
esis exist. Ultimately, the collagen within the lesions is
disrupted, and the resulting inflammatory response
causes the clinical findings. oriented across the entire biopsy specimen in a layered response. Intralesional corticosteroids can be used in
Histology: The histological findings in biopsy speci- fashion. Histological variants of granuloma annulare some cases, but the risk of atrophy from the steroid
mens of granuloma annulare are very specific. There exist, including interstitial granuloma annulare. injection must be considered. Generalized forms are
are areas of necrobiotic collagen with a surrounding Treatment: Localized forms of granuloma annulare not amenable to topical therapy. Phototherapy has been
granulomatous infiltrate. The collagen is being des- that are asymptomatic and not causing any distress to used successfully. Psoralen + ultraviolet A light (PUVA)
troyed centrally. A varying amount of mucin is present. the patient can be left alone. Most cases resolve spon- therapy has had more success than ultraviolet B (UVB)
The main histological differential diagnosis is between taneously over time with no residual scarring and no light therapy, most likely because UVA light penetrates
granuloma annulare and necrobiosis lipoidica. The clinically noticeable abnormality. Topical corticoste- deeper into the dermis than UVB. Phototherapy with
inflammation in necrobiosis lipoidica is typically roids may be used to try to decrease the inflammatory UVA 1 appears promising.

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