the red leg basic dermatology curriculum last updated june 16, 2011 1

The Red Leg

Basic Dermatology Curriculum

Last updated June 16, 20111

Module Instructions

The following module contains a number of blue, underlined terms which are hyperlinked to the dermatology glossary, an illustrated guide to clinical dermatology and dermatopathology.

We encourage the learner to read all the hyperlinked information.

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Goals and Objectives

The purpose of this module is to help medical students develop a clinical approach to the evaluation and initial management of patients presenting with an erythematous leg.

By completing this module, the learner will be able to:• Recognize common and life-threatening causes of an

erythematous leg

• List the various risk factors for the conditions presented in this module

• Describe the initial treatment plans for each condition presented in this module

• Determine when to refer patients presenting with a red leg to a dermatologist or other specialty

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Case One

Mr. Roy Clarke

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Case One: History

HPI: Mr. Clarke is a 55-year-old man who presents with 5 days of worsening right lower extremity pain and a red rash. He reports recent fevers and chills since he returned from a camping trip last week.

PMH: arthritis Medications: occasional NSAIDs, multivitamin Allergies: no known drug allergies Family history: father with history of melanoma Social history: lives in the city with his wife, two grown

children Health-related behaviors: no alcohol, tobacco or drug use ROS: able to bear weight, no itching

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Vital signs: T 100.4, HR 90, BP 120/70, RR 14, O2 sat 97% on RA

Skin: erythematous plaque with ill-defined borders over the right medial malleolus. Lesion is tender to palpation. With lymphatic streaking (not shown).

Tender, slightly enlarged right inguinal lymph nodes (not shown)

Laboratory data: Wbc 12,000 (75% neutrophils, 10% bands), Hct 44, Plts 335

Case One: Exam

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Case One, Question 1

What is the most likely diagnosis?a. Bacterial folliculitis

b. Cellulitis

c. Necrotizing fasciitis

d. Stasis dermatitis

e. Tinea corporis

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Case One, Question 1

Answer: b What is the most likely diagnosis?

a. Bacterial folliculitis (Would expect pustules and papules centered on hair follicles. Without systemic signs of infection.)

b. Cellulitisc. Necrotizing fasciitis (Would expect rapidly expanding rash, usually

appears as a dusky, edematous, red plaque. In this setting, it is always appropriate to ask the question, “Could this be necrotizing fasciitis?”)

d. Stasis dermatitis (Although found in similar location, stasis dermatitis often presents with pruritus and scale, which may erode or crust. Without fever or elevated wbc.)

e. Tinea corporis (Would expect annular plaque with elevated border and central clearing. Painless, without fever or elevated wbc.)

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Diagnosis: Cellulitis

Cellulitis is a very common infection occurring in up to 3% of people per year

Results from an infection of the dermis that often begins with a portal of entry such as a wound or fungal infection (e.g., tinea pedis)

Group A beta-hemolytic streptococci and Staphyloccocus aureus are the most common causal pathogens

Presents as a spreading erythematous, non-fluctuant tender plaque

More commonly found on the lower leg Streaks of lymphangitis may spread from the area to the

neighboring lymph glands9

Erysipelas

Erysipelas is a superficial cellulitis with marked dermal lymphatic involvement (causing the skin to be edematous or raised)

Main pathogen is group A streptococcus Usually affects the lower extremities and the face Presents with pain, superficial erythema, and plaque-like

edema with a sharply defined margin to normal tissue Plaques may develop overlying blisters (bullae) May be associated with a high white count (>20,000/mcL) May be preceded by chills, fever, headache, vomiting, and

joint pain10

Example of Erysipelas

Large, shiny erythematous plaque with sharply demarcated borders located on the posterior leg

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Back to Case One

Mr. Clarke was diagnosed with cellulitis.

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Case One, Question 2

What is the next best step in management?a. Apply topical antibiotics

b. Apply topical steroids, compression wraps, and encourage leg elevation

c. Begin antibiotics immediately with coverage for gram positive bacteria

d. Order an imaging study

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Case One, Question 2

Answer: c What is the next best step in management?

a. Apply topical antibiotics (not effective)

b. Apply topical steroids, compression wraps, and encourage leg elevation (this is the treatment for stasis dermatitis, not cellulitis)

c. Begin antibiotics immediately with coverage for gram positive bacteria

d. Order an imaging study (radiographic examination is not necessary for routine evaluation of patients with cellulitis)

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Cellulitis: Treatment

It is important to recognize and treat cellulitis early as untreated cellulitis may lead to sepsis and death

May use the following guidelines for empiric antibiotic therapy:• For outpatients with nonpurulent cellulitis: empirically treat for

β-hemolytic streptococci (group A streptococcus)• Some clinicians choose an agent that is also effective against S.

aureus• For outpatients with purulent cellulitis (purulent drainage or

exudate in the absence of a drainable abscess): empirically treat for community-associated MRSA

• For unusual exposures: cover for additional bacterial species likely to be involved

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Cellulitis: Treatment (cont.)

Monitor patients closely and revise therapy if there is a poor response to initial treatment

Elevation of the involved area Treat tinea pedis if present For hospitalized patients: empiric therapy for

MRSA should be considered Cultures from abscesses and other purulent skin

and soft tissue infections (SSTIs) are recommended in patients treated with antibiotic therapy

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Case Two

Mr. Anthony Bice

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Case Two: History

HPI: Mr. Bice is a 66-year-old man who was admitted for an inguinal hernia repair. His surgery went well and he was recovering without complication until he was found to have an expanding red rash on his left thigh. The dermatology service was consulted for evaluation of the rash.

PMH: hypertension, diabetes mellitus type 2 Medications: lisinopril, insulin, oxycodone Allergies: none Family history: noncontributory Social history: retired, lives with his wife Health-related behaviors: reports no alcohol, tobacco, or drug use ROS: febrile, fatigue, rash is painful

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Case Two: Exam

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Vital signs: T 101.1, HR 110, BP 90/50, RR 18, O2 sat 98% General: ill-appearing gentleman lying in bed Skin: ill-defined, anesthetic, large erythematous plaque with

central patches of dusky blue discoloration; upon re-examination 60 minutes later, the redness had spread

Case Two, Question 1

Which of the following do you recommend for initial management?

a. Call an urgent surgery consult

b. Give IV fluids and antibiotics

c. Image with stat MRI

d. Obtain a deep skin biopsy

e. All of the above

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Case Two, Question 1

Answer: e Which of the following do you recommend for initial

management?a. Call an urgent surgery consult (The suspected diagnosis is a

surgical emergency.)

b. Give IV fluids and antibiotics (Patients quickly become hemodynamically unstable.)

c. Image with stat MRI (To assess degree of soft tissue involvement. Appropriate, but do not delay surgical intervention.)

d. Obtain a deep skin biopsy (Helps confirm diagnosis.)

e. All of the above 21

Diagnosis: Necrotizing Fasciitis

Necrotizing fasciitis is a life-threatening infection of the fascia just above the muscle

Progresses rapidly over the course of hours and may follow surgery or trauma, or have no preceding visible lesion

Expanding dusky, edematous, red plaque with blue discoloration • May turn purple and blister• Anesthesia of the skin of the affected area is a

characteristic finding Caused by group A streptococcus, Staphylococcus aureus,

or a variety of other organisms22

Necrotizing Fasciitis: Treatment

Considered a medical/surgical emergency with up to a 20% fatality rate

If suspect necrotizing fasciitis, consult surgery immediately

Treatment includes widespread debridement and broad-spectrum systemic antibiotics

Poor prognostic factors include: delay in diagnosis, age > 50, diabetes, atherosclerosis, infection involving the trunk

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Case Three

Ms. Janet Frasier

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Case Three: History

HPI: Ms. Frasier is a 43-year-old woman with a recent diagnosis of gout who presents to her primary care provider with a diffuse rash on her lower extremities. The rash began 4 days after starting indomethacin for an acute gout attack.

PMH: gout, no hospitalizations or surgeries Medications: indomethacin, zolpidem Allergies: none Social history: lives by herself in an apartment Health-related behaviors: history of significant alcohol use,

last drink 3 years ago. No tobacco or drug use. ROS: no current fevers, sweats or chills

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Case Three: Skin Exam

Normal vital signs General: appears well in

NAD Skin exam: palpable

hemorrhagic papules coalescing into plaques, bilateral and symmetric on lower extremities

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Case Three, Question 1

Which of the following is the most likely cause of Ms. Frasier’s skin findings?

a. DIC secondary to sepsis

b. Leukocytoclastic vasculitis secondary to NSAID

c. Septic emboli with hemorrhage from undiagnosed bacterial endocarditis

d. Urticarial vasculitis

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Case Three, Question 1

Answer: b Which of the following is the most likely cause of Ms.

Frasier’s skin findings?a. DIC secondary to sepsis (Ms. Frasier’s history and exam are

less concerning for sepsis. Skin lesions of DIC tend to occur on acral and distal sites, with a retiform (netlike) purpura.)

b. Leukocytoclastic vasculitis secondary to NSAID

c. Septic emboli with hemorrhage from undiagnosed bacterial endocarditis (Ms. Frasier has no known risk factors for endocarditis and lesions tend to occur on the distal extremities.)

d. Urticarial vasculitis (Presents with a different morphology, which is urticarial.)

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Palpable Purpura

Palpable purpura results from inflammation of small cutaneous vessels, i.e. vasculitis

Vessel inflammation results in vessel wall damage and in extravasation of erythrocytes seen as purpura on the skin

Vasculitis may occur as a primary process or may be secondary to another underlying disease

Palpable purpura is the hallmark lesion of leukocytoclastic vasculitis (small vessel vasculitis)

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Vasculitides According to Size of the Blood Vessels

Small vessel vasculitis (leukocytoclastic vasculitis)• Henoch-Schönlein purpura• Other:

• Idiopathic• Malignancy-related• Rheumatologic• Infection• Medication

• Urticarial vasculitis

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Vasculitides According to Size of the Blood Vessels

Predominantly Mixed (Small + Medium)• ANCA associated vasculitides

• Churg-Strauss syndrome• Microscopic polyangiitis• Wegener granulomatosis

• Essential cryoglobulinemic vasculitis Predominantly medium sized vessels

• Polyarteritis nodosa Predominantly large vessels

• Giant cell arteritis• Takayasu arteritis

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Clinical Evaluation of Vasculitis

The following laboratory tests may be used to evaluate patient with suspected vasculitis:

• CBC with platelets • ESR (systemic vasculitides tend to have sedimentation rates > 50)• ANA (a positive antinuclear antibody test suggests the presence of an

underlying connective tissue disorder)• ANCA (helps diagnose Wegener granulomatosis, microscopic

polyarteritis, drug-induced vasculitis, and Churg-Strauss) • Complement (low serum complement levels may be present in mixed

cryoglobulinemia, urticarial vasculitis and lupus)• Urinalysis (helps detect renal involvement)

Also consider ordering cryoglobulins, an HIV test, HBV and HCV serology, occult stool samples, an ASO titer and streptococcal throat culture

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Diagnosis: Leukocytoclastic Vasculitis (LCV)

The primary care provider also suspects LCV secondary to medication hypersensitivity, but to make sure she has not missed any other causes of vasculitis she orders laboratory tests and refers the patient to a dermatologist

Ms. Frasier was recommended to stop the indomethacin

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Case Four

Mrs. Belinda Strong

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Case Four: History

HPI: Mrs. Strong is a 60-year-old woman who presents with a “rash” on her leg that has been present for 2 months. She reports no pain, but does experience mild pruritus.

PMH: diabetes (last hemoglobin A1c was 6.7), hypertension, obesity. No history of atopic dermatitis.

Medications: lisinopril, metoprolol, glyburide Allergies: none Family history: mother with diabetes and hypertension Social history: lives with her husband in the city, four grown

children, two grandchildren Health-related behaviors: no tobacco, alcohol or drug use ROS: no leg pain when walking or at rest

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Case Four, Question 1

How would you describe these skin findings?

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Case Four, Question 1

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Large erythematous plaques with fine fissuring and scale as well as interspersed brown macular hyperpigmentation

Case Four, Question 2

What is the most likely diagnosis?a. Atopic dermatitis

b. Bilateral cellulitis

c. Stasis dermatitis

d. Tinea corporis

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Case Four, Question 2

Answer: c What is the most likely diagnosis?

a. Atopic dermatitis (adults with AD have a history of childhood AD and a different distribution of skin involvement)

b. Bilateral cellulitis (cellulitis occurs more acutely, presents with fever and pain, more erythema, well-demarcated and without pruritus or scale)

c. Stasis dermatitisd. Tinea corporis (would expect sharply marginated,

erythematous annular patches with central clearing)39

Diagnosis: Stasis Dermatitis

Stasis dermatitis typically presents with erythema, scale, pruritus, erosions, exudate, and crust• Usually located in the lower third of

the legs, superior to the medial malleolus

• Can occur bilaterally or unilaterally• Lichenification may develop• Edema is often present, as well as

varicose veins and hemosiderin deposits (pinpoint yellow-brown macules and papules)

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More Examples of Stasis Dermatitis

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More Examples of Stasis Dermatitis

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Case Four, Question 3

Which of the following treatments do you recommend for Mrs. Strong ?

a. Leg elevation, compression therapy

b. Leg elevation, topical antibiotics

c. Leg elevation, topical corticosteroids, compression therapy

d. Topical corticosteroids

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Case Four, Question 3

Answer: c Which of the following treatments do you

recommend for Mrs. Strong?a. Leg elevation, compression therapy

b. Leg elevation, topical antibiotics

c. Leg elevation, topical corticosteroids, compression therapy

d. Topical corticosteroids

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Stasis Dermatitis: Treatment

Important to treat both the dermatitis and the underlying venous insufficiency

• Application of super-high and high potency steroids to area of dermatitis under a wrap

• Elevation (to reduce edema)

• Compression therapy with leg wraps*

• Change wraps weekly, or more often if the lesion is very weepy

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* Establish pedal pulses prior to using compression wraps. See the Stasis Dermatitis and Leg Ulcers module for more information.

Case Four (cont.)

Mrs. Strong returns for a follow-up visit 6 months later. She was able to adhere to the regimen of topical corticosteroids, leg elevation and compression therapy for the first few weeks, but then became preoccupied with a new grandbaby and stopped the treatment altogether.

A few months later she noticed a weeping wound on the same leg. She has been applying an over-the-counter topical ointment.

She now reports mild pain and worsening pruritus.

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Case Four: Exam

Vital signs: normal

Skin: erythematous plaque located on the medial left leg with a shallow ulcer with a fibrinous base and some serous exudate

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Case Four, Question 4

What is the most likely diagnosis?a. Cellulitis

b. Contact dermatitis

c. Necrotizing fasciitis

d. Vasculitis

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Case Four, Question 4

Answer: b What is the most likely diagnosis?

a. Cellulitis (history of topical ointment and pruritus are more consistent with contact dermatitis, also patient is afebrile)

b. Contact dermatitis

c. Necrotizing fasciitis (would expect fever and other systemic signs and symptoms)

d. Vasculitis (would expect palpable purpura) 49

Contact Dermatitis

Mrs. Strong has a contact dermatitis secondary to an over-the-counter antibiotic ointment.

Patients with leg ulcers have a high incidence of allergic contact dermatitis due to frequent and prolonged use of topical products as well as a disrupted skin barrier in the areas of use.

Leg ulcers may become persistent or recurrent due to ongoing dermatitis and exposure to contact allergens.

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Case Four, Question 5

Which of the following recommendations would you provide Mrs. Strong?

a. Compression therapyb. Leg elevation c. Local wound care with semi-permeable

primary dressing d. Stop topical antibiotics e. Topical corticosteroids to dermatitisf. All of the above

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Case Four, Question 5

Answer: f Which of the following recommendations would

you provide Mrs. Strong?a. Compression therapyb. Leg elevation c. Local wound care with semi-permeable primary

dressing d. Stop topical antibiotics e. Topical corticosteroids to dermatitisf. All of the above

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Case Five

Ms. April Kapp

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Case Five: History and Exam

Ms. Kapp is a 72-year-old woman who presents to her primary care provider with a “very itchy rash” on her lower extremities.

Skin Exam: well-marginated plaque with cracking of the skin resembling a dried lake bed

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Case Five, Question 1

Which of the following history items likely contributes to her condition?

a. Bathing daily with soap

b. Her age - elderly

c. Using the heater during the winter

d. All of the above

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Case Five, Question 1

Answer: d Which of the following history items likely

contributes to her condition?a. Bathing daily with soap

b. Her age - elderly

c. Using the heater during the winter

d. All of the above

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Diagnosis: Asteatotic Dermatitis

Also called Xerotic Eczema Common pruritic dermatitis caused by the

loss of the epidermal water barrier More common in the elderly Worsened by frequent hot showers,

deodorant soaps Worse in the winter (low humidity of heated

houses) and in higher altitudes57

Asteatotic Dermatitis

Affects lower legs, flanks, arms Spares armpits, groin, face Early signs:

• flaking of the skin, pruritic Evolved:

• cracking of the skin looking like the bed of a dry lake

• itchy and stings Can become severe:

• weepy dermatitis, pruritic58

Asteatotic Dermatitis: Evaluation and Treatment

Diagnostic Pearl • Pruritus is relieved by prolonged submersion in bath (20-30

minutes). Pruritus then resumes 5-30 minutes after getting out of the water.

Treatment• Moisturize with emollient ointments

• Soap to the axillae, groin, scalp only

• Medium potency topical steroid ointment to the areas of erythema and pruritus

• Severe cases: soak in tub 20 minutes, apply medium potency topical ointment, covered with occlusive dressing overnight

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Common Causes of the Red Leg

Infection Vasculitis Stasis dermatitis Contact dermatitis Asteatotic dermatitis

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What’s the Diagnosis?

A B

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Contact Dermatitis

A

Bilateral red plaques surrounding central erosions/ulcers involving the dorsal feet and anterior shins

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Asteatotic Dermatitis

B

Erythematous plaque on the skin with a “dried river bed” appearance

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What’s the Diagnosis?

D

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C

Stasis Dermatitis

C

Bilateral lower extremity edema with violaceous, symmetrical plaques, scaling and lichenification

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Leukocytoclastic Vasculitis

D

Petechiae and erythematous papules densely scattered over the posterior legs.

Non-blanching (not shown)

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What’s the Diagnosis?

E

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F

Necrotizing Fasciitis

E

Erythematous plaque on the anterior thigh with dusky, necrotic areas and a few overlying flaccid bullae

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Cellulitis

Erythematous, edematous, confluent plaque on the leg with a central bulla and lymphangitic streaking

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F

Take Home Points

It is important to recognize and treat cellulitis early Necrotizing fasciitis is a medical and surgical emergency

with up to a 20% fatality rate Leukocytoclastic vasculitis presents as palpable purpura

and is secondary to a variety of causes including medications

The treatment of stasis dermatitis includes elevation, compression, topical steroids, and the avoidance of topical antibiotics

Asteatotic dermatitis is a pruritic dermatitis that occurs more commonly in the elderly

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Acknowledgements

This module was developed by the American Academy of Dermatology Medical Student Core Curriculum Workgroup from 2008-2012.

Primary authors: Sarah D. Cipriano, MD, MPH; Eric Meinhardt, MD; Timothy G. Berger, MD, FAAD; Lindy Fox, MD, FAAD.

Peer reviewers: Daniela Kroshinsky, MD, FAAD; Cory A. Dunnick, MD, FAAD; Jenny Swearingen, MD.

Revisions and editing: Sarah D. Cipriano, MD, MPH; Jillian W. Wong. Last revised June 2011.

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References

Berger T, Hong J, Saeed S, Colaco S, Tsang M, Kasper R. The Web-Based Illustrated Clinical Dermatology Glossary. MedEdPORTAL; 2007. Available from: www.mededportal.org/publication/462.

James WD, Berger TG, Elston DM, “Chapter 14. Bacterial Infections”. Andrews’ Diseases of the Skin Clinical Dermatology. 11th ed. Philadelphia, Pa: Saunders Elsevier; 2011: Fig 14-19 Necrotizing fasciitis, page 256.

Saap L, et al. Contact Sensitivity in Patients With Leg Ulcerations. Arch Dermatol. 2004;140:1241-1246.

Saavedra Arturo, Weinberg Arnold N, Swartz Morton N, Johnson Richard A, "Chapter 179. Soft-Tissue Infections: Erysipelas, Cellulitis, Gangrenous Cellulitis, and Myonecrosis" (Chapter). Wolff K, Goldsmith LA, Katz SI, Gilchrest B, Paller AS, Leffell DJ: Fitzpatrick's Dermatology in General Medicine, 7e: http://www.accessmedicine.com/content.aspx?aID=2994981.

Wolff K, Johnson RA, "Section 2. Eczema/Dermatitis" (Chapter). Wolff K, Johnson RA: Fitzpatrick's Color Atlas & Synopsis of Clinical Dermatology, 6e: http://www.accessmedicine.com/content.aspx?aID=5190332.

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