The Red Leg
Basic Dermatology Curriculum
Last updated June 16, 2011
1
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.
2
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
3
Case One
Mr. Roy Clarke
4
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
5
Case One: Exam
Vital signs: T 100.4, HR 90, BP 120/70,
RR 14, O2 sat 97% on RA
Skin: erythematous plaque with illdefined 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
6
Case One, Question 1
 What is the most likely diagnosis?
a.
b.
c.
d.
e.
Bacterial folliculitis
Cellulitis
Necrotizing fasciitis
Stasis dermatitis
Tinea corporis
7
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. Cellulitis
c. 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.)
.8
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 glands
9
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 pain
10
Example of Erysipelas
Large, shiny erythematous
plaque with sharply
demarcated borders located
on the posterior leg
11
Back to Case One
Mr. Clarke was diagnosed with cellulitis.
12
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
13
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)
14
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
15
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
16
Case Two
Mr. Anthony Bice
17
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
18
Case Two: Exam
 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 reexamination 60 minutes later, the redness had spread
19
Case Two, Question 1
 Which of the following do you recommend
for initial management?
a.
b.
c.
d.
e.
Call an urgent surgery consult
Give IV fluids and antibiotics
Image with stat MRI
Obtain a deep skin biopsy
All of the above
20
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 organisms
22
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
23
Case Three
Ms. Janet Frasier
24
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
25
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
26
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
27
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.)
28
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)
29
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
30
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
31
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
32
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
33
Case Four
Mrs. Belinda Strong
34
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
35
Case Four, Question 1
How would you
describe these skin
findings?
36
Case Four, Question 1
Large erythematous
plaques with fine
fissuring and scale
as well as
interspersed brown
macular
hyperpigmentation
37
Case Four, Question 2
 What is the most likely diagnosis?
a.
b.
c.
d.
Atopic dermatitis
Bilateral cellulitis
Stasis dermatitis
Tinea corporis
38
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 dermatitis
d. 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)
40
More Examples of Stasis
Dermatitis
41
More Examples of Stasis
Dermatitis
42
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
43
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
44
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
* Establish pedal pulses prior to using compression wraps. See the Stasis
Dermatitis and Leg Ulcers module for more information.
45
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-thecounter topical ointment.
 She now reports mild pain and worsening pruritus.
46
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
47
Case Four, Question 4
 What is the most likely diagnosis?
a.
b.
c.
d.
Cellulitis
Contact dermatitis
Necrotizing fasciitis
Vasculitis
48
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.
50
Case Four, Question 5
 Which of the following recommendations
would you provide Mrs. Strong?
a. Compression therapy
b. Leg elevation
c. Local wound care with semi-permeable
primary dressing
d. Stop topical antibiotics
e. Topical corticosteroids to dermatitis
f. All of the above
51
Case Four, Question 5
Answer: f
 Which of the following recommendations would
you provide Mrs. Strong?
a. Compression therapy
b. Leg elevation
c. Local wound care with semi-permeable primary
dressing
d. Stop topical antibiotics
e. Topical corticosteroids to dermatitis
f. All of the above
52
Case Five
Ms. April Kapp
53
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
54
Case Five, Question 1
 Which of the following history items likely
contributes to her condition?
a.
b.
c.
d.
Bathing daily with soap
Her age - elderly
Using the heater during the winter
All of the above
55
Case Five, Question 1
Answer: d
 Which of the following history items likely
contributes to her condition?
a.
b.
c.
d.
Bathing daily with soap
Her age - elderly
Using the heater during the winter
All of the above
56
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 altitudes
57
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, pruritic
58
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
59
Common Causes of the Red Leg





Infection
Vasculitis
Stasis dermatitis
Contact dermatitis
Asteatotic dermatitis
60
What’s the Diagnosis?
A
B
61
Contact Dermatitis
A
Bilateral red plaques
surrounding central
erosions/ulcers involving
the dorsal feet and
anterior shins
62
Asteatotic Dermatitis
B
Erythematous plaque
on the skin with a “dried
river bed” appearance
63
What’s the Diagnosis?
C
D
64
Stasis Dermatitis
C
Bilateral lower extremity
edema with violaceous,
symmetrical plaques,
scaling and
lichenification
65
Leukocytoclastic Vasculitis
D
Petechiae and
erythematous papules
densely scattered over
the posterior legs.
Non-blanching (not
shown)
66
What’s the Diagnosis?
E
F
67
Necrotizing Fasciitis
E
Erythematous plaque
on the anterior thigh
with dusky, necrotic
areas and a few
overlying flaccid bullae
68
Cellulitis
Erythematous,
edematous,
confluent plaque on
the leg with a central
bulla and
lymphangitic
streaking
F
69
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
70
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.
71
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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