DermHelpCentral

Mimics of Cellulitis

Distinguishing true cellulitis from its many imitators is challenging but critical if we are to avoid unnecessary use of antibiotics and delays in treatment. Common imitators of cellulitis are stasis dermatitis, lipodermatosclerosis, contact dermatitis, lymphedema, eosinophilic cellulitis, and papular urticaria. Specific criteria do not exist for the diagnosis of cellulitis, but the alert physician can find clues in the history and physical examination that point toward cellulitis.

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Ocult Facial Contact Dermatitis

Dr, Howard Maibach had very useful comments regarding VGRD presentation of 44 yo woman with facial erythema.

See: Download Consultation with Howard Maibach regarding this woman with a red face

Poison Ivy Overview

Jane Brody had a great overview of "poison ivy dermatitis" in the June 17, 2014 NY Times. There are two factual errors, but overall this is an extremely useful overview.

Brody states: "Myths and misconceptions abound about these three plants and the reactions they can cause. Knowing the facts can help to spare you and your family considerable distress."  Her fine piece will enable you to avoid some of these. See: "Steering Clear of Poison Ivy"

The errors:

1) Brody states: "Even people repeatedly exposed who appear to be immune may react to high concentrations of the toxin."   Immunity is a state of sensitization or reactivity.  The correct term is tolerant, or "exhibit immune tolerance."  The immune system has a mechanism of turning off "immune reactivity."  Therefore, the sentence should read, "Even people repeatedly exposed who appear to be tolerant may become sensitized."

2. When she states "Nor do you become immune to urushiol through repeated exposures to small amounts. Quite the opposite. There is no way to desensitize a person to urushiol as there is with pollen and peanut allergies.  Eating mangoes or cashews will not work." This is not true!  In a natural "experiment' with millions of persons, it has been shown that individuals who are reared in areas where mangos grow are most often "tolerant" to the poison ivy resin and related urushiols.  It appears that early exposure (especially via the oral route) induces specific immune tolerance.  This is difficult, and often impossible, to induce once immunity has been established.

References:
1. The Baleful Weed by Wayne Winterrowd.  The author describes how he was desensitized, as a young child, to poison ivy.
2. Exploring the mango-poison ivy connection: the riddle of discriminative plant dermatitis.  Hershko K, Weinberg I, Ingber A. Contact Dermatitis. 2005 Jan;52(1):3-5.
Abstract: Our observations suggest that individuals with known history of poison ivy/oak allergy, or those residing in area where these plants are common, may develop allergic contact dermatitis from mango on first exposure. We hypothesize that previous oral exposure to urushiol in the local Israeli population might establish immune tolerance to these plants.

 

Use Tests for Skin Allergy

This is a good article on testing to see if one is truly sensitive to a given agent applied to the skln.  There are two tests: the Repeated Open Application Test (ROAT) and the Provocative Use Test (PUT).  Here's the article: Download J_002

Generally, the skin in  front of the elbow is a good place to use for the ROAT.  Apply a small  amount of the cream/ointment/spray -- etc. a couple of times a day for a few days -- if no reaction within 4 - 5 days -- one is probably not sensitive to the agent.

Here's the abstract of the pdf above.

As one step in defining the clinical relevance of exposure to an allergen identified with patch
testing, use tests (provocative use test (PUT), and repeated open application test (ROAT)) have
been used. In 1/2 of the cases of seemingly reliable patch tests, use tests are negative, suggesting
that the patient’s biologic threshold of response had not been reached with open application dosing.
Dramatic differences exist in regional skin reactivity and percutaneous penetration. Negative
results of use tests on normal skin may become positive on diseased skin. To refine this assay
further, more controlled observations and analysis of reaction differences between normal and
damaged skin, and among regional anatomic sites might be performed. In addition, we require a
standardized measurement for the results. Use testing has significant potential in refinement of the
evidence-based diagnosis of clinical relevance. However, for general validation, we should fill the
deficiencies described above.

Topical Steroid Potency Chart

 Topical steroid preparations are grouped according to relative anti-inflammatory activity, but activity may vary considerably depending upon the vehicle (cream, ointment, solution, foam, etc.), the site of application (face, skin folds and genitalia), disease, the individual patient and whether or not an occlusive dressing is used.  In addition,there are a number of these charts and they are not entirely consistent.  The National Psoriasis Foundation's Potency Chart is well-prepared and a good general guide.

Topical steroids should be used under your doctor's direction, since overuse can cause thinning of the skin, rosacea, acne, stretch marks if used on the wrong part of the body and for too long.  .

Plants That Cause Rashes

Dermnet, a database from New Zealand, is the brainchild of New Zealand dermatologist, Amanda Oakley.  It has a great section on plants that cause skin rashes.  You can find most of the key players there.

Cow Parsnip Dermatitis (aka Hogweed)

This is a very common weed which grows along the roads and fields in New England. 

DermNet has a good section:

"Botanical name:     Heracleum spondylium

Family:     It belongs to the Apiaceae family (or Umbelliferae), which has over 2500 species in 275 genera. These include common herbs such as giant hogweed, anise, carrot, celery, coriander, dill, fennel, parsley, and parsnip, as well as the highly toxic hemlocks.

Origin:     Native to the British Isles.

Description:     The Apiaceae family are characterised by alternate leaves, which widen at the base into a sheath that clasps the stem. The stems are often furrowed with the flowers usually compound, almost always concentrated in flat-topped umbels. The flowers have 5 petals, usually uneven, and 5 stamens. Seeds and fruit form below where the petals and stamen originate Some parts of the plant usually have a strong aroma, due primarily to various oils produced by the plant.

(Photos taken in Williamastown, MA)

 

Uses:     Cow parsnip, often grows in moist meadows, and along the borders of fields, and near ditches. Traditionally the young leaf stalks and stems were eaten like stewed celery. The leaves may be dried, burned and the ashes used as a salt substitute. Native Americans of the northern US ate the peeled stalks raw or cooked. The blossoms were steeped in oil and rubbed on the body to keep off flies and mosquitoes.

Allergens:     Furocoumarins (psoralens) including bergapten, isobergapten, sphondin, isopimpinellin and pimpinellin.

Allergy:   The umbilliferae contain furano-coumarins which, when exposed to sunlight, cause significant photo-toxic reactions (photosensitivity). One of the more common skin reactions to Cow parsnip/hogweed, is the ‘weed wackers’ or ‘string trimmers’ dermatitis. When string trimmers are used to clear long grass, components of weeds are usually mulched and scattered in all directions, often coating the legs and arms of the operator. The sap of the plants then gets on the skin, and, when exposed to sunlight, gives rise to a very characteristic rash which may persist for many months."

Reference:  Oakley AM, Ive FA, Harrison MA. String trimmer's dermatitis. J Soc Occup Med. 1986 Winter;36(4):143-4.

Breast Eczemas

Toronto dermatologist, Benjamin Barankin and M. Shirley Gross wrote an important article on nipple and areolar dermatitis in breast feeding women in 2004.  This is of great import.

Abstract.  Eczema of the nipple and areola can occasionally develop in the breastfeeding patient and is associated with sore, burning, and painful areolae and nipples. Management includes elimination of any precipitating allergens and irritant and the judicious use of appropriate topical corticosteroid preparations. Patients must also be offered effective pain control and support. The proper diagnosis and management of eczema of the nipple and areola in breastfeeding patients will prevent premature and iatrogenic weaning.

This is an important area for pregnant and breast feeding women.  Often, eczema is the underlying cause, compounded by secondary infection and/or contact dermatitis. It may be that the immune dysregulation of pregnancy contributes to this subset of eczema.  DJE

The pdf is here for those who need more information see:  Download Nipple and Areolar Eczema i

Dermatologic Disaster: Poison Oak Show

From the September 27, 2007 NY Times

"Let leaf-peepers in New England ooh and aah over maples and mulled cider: here, [in Columbia, Califronis] fearless citizens risk dermatological disaster to harvest comely sprays of Toxicodendron diversilobum for what may be the country’s strangest autumn ritual: the Annual Poison Oak Show."
Full text at Permalink

The Champions of Poison Oak