48 year old woman with circular rash on the back of her hands
48 year old woman with circular rash on the back of her hands for 6 months. The
areas were moderately pruritic. She was diagnosed as having ?ringworm?. She has
treated the lesions with a prescription topical antifungal cream twice daily
for 3 weeks with minimal to no improvement. On examination there was very minimal
scale, and a potassium hydroxide (KOH) microscopic examination of scraped skin
(once again scale was difficult to obtain) failed to detect fungus (spores or
hyphae). The patient had no other medical conditions, including diabetes.
What is your diagnosis?
Granuloma annulare is an idiopathic condition
where histocytes congregate in the dermis. This can cause an annular lesion but
the key to diagnosis is that the epidermis is not involved. There is no scale.
Take a look at the side by side comparison of true ringworm (tinea corporis)
and granuloma annulare pictured below. Most commonly one sees annular lesions
that are bumpy without scale. I also see this commonly near the ankles where
the lesions tend to be flatter, but they are annular lesions with central clearing
and are purple to lilac in color. There are several variants (papular, nodular,
patch, and classic annular) as demonstrated in the photographs below. Again,
please also note the scale present on the picture of the ringworm (tinea corporis)
and the striking ?lack of scale? seen in the classic annular type, shown side
by side for comparison. In the past there was a thought that patients were at
higher risk for developing diabetes, but this connection is no longer favored.
The treatment of granuloma annulare is not necessary
unless symptomatic. If the lesions are pruritic, I will often use a mild topical
steroid cream such as Westcort cream twice daily. In cases of troubling pruritus,
I will do mild steroid injections (kenalog 2.5-5.0 gm/cc) into multiple sites,
as I did in this case (please not the successful before and after photographs
above). If the diagnosis is unclear, certainly a diagnosis will provide the answer.
An interesting observation seen with granuloma annulare sometimes is jokingly
referred to as a 'therapeutic biopsy'. That is, oftentimes you can perform a
diagnostic skin biopsy on a portion of the lesion and the entire lesion disappears
over several days after the biopsy. Steroid injections can work well in cases
of symptomatic or cosmetic concern . There are other, less common variants of
granuloma annulare mentioned above and another generalized papular variant, too.
Once again, patients should be given reassurance that the condition is benign
and treatment is indicated if the lesions are of a symptomatic or cosmetic concern.
Tinea corporis (a.k.a. 'ringworm', note the PRESENCE of scale)
Classic Granuloma Annulare (note the ABSENCE of scale)
Granuloma Annulare nodular variant b
Granuloma Annulare lilac color patch variant
Granuloma Annulare nodular variant
Granuloma Annulare papular variant
Widespread papular variant
Charles E. Crutchfield III, MD
Clinical Adjunct Associate Professor of Dermatology
University of Minnesota Medical School
Medical Director, Crutchfield Dermatology