1. Medical Student Core Curriculum in Dermatology
Erythema Nodosum
Medical Student Core Curriculum
in Dermatology
Last updated March 23, 2011

2. Modules Instructions
The following module contains a number of blue, underlined terms which are hyperlinked to the dermatology glossary, an illustrated interactive guide to clinical dermatology and dermatopathology.
We encourage the learner to read all the hyperlinked information.

3. 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 erythema nodosum.
By completing this module, the learner will be able to:
Identify and describe the morphology of erythema nodosum
Name conditions associated with erythema nodosum
Recommend an initial treatment plan for a patient with erythema nodosum
Discuss when to refer to a patient with erythema nodosum to a dermatologist

4. Case One
Mrs. Cheryl Mosely

5. Case One: History
HPI: Mrs. Mosely is a 35-year-old woman who presents to her primary care physician with tender red “bumps” on her anterior shins. The lesions appeared over the course of a few days and have started to resolve with faint bruises remaining. She also reports a recent history of a sore throat and fever two weeks ago, which improved after a course of antibiotics.
PMH: no major illness or hospitalizations
Medications: none aside from recent antibiotic course
Allergies: none
Family history: noncontributory
Social history: lives with husband and 12-year-old child who also had a sore throat
Health-related behaviors: no tobacco, alcohol, or drug use
ROS: no cough or rhinorrhea

6. Case One: Exam Vital signs: normal Gen: well-appearing HEENT: normal
Skin: multiple scattered shiny, red nodules on the anterior shins bilaterally

7. Case One, Question 1 What is the appropriate next step?
Anti-Streptolysin O titer
Biopsy the lesion
Drain the nodules
Topical steroid ointment

8. Case One, Question 1 Answer: a What is the appropriate next step?
Anti-Streptolysin O titer
Biopsy the lesion (diagnosis can be made clinically)
Drain the nodules (lesions are more inflammatory vs. abscess)
Topical steroid (not effective)

9. Diagnosis: Erythema Nodosum
Mrs. Mosely’s recent history of sore throat and fever is suggestive of acute pharyngitis. Her ASO titer came back elevated.
The lesions on her legs were diagnosed as erythema nodosum.

10. Erythema Nodosum (EN)
Characterized by the presence of painful, erythematous, non-ulcerative nodules
Often symmetric distribution, located bilaterally below the knees (mainly on the anterior tibial surface)
Lesions evolve from bright red to brown-yellow, resembling old ecchymoses
Old and new lesions often coexist
Patients may also present with fever, fatigue, and arthralgias
The morphology of the lesion, a deep nodule, identifies EN as an inflammatory disease of the fat (called a panniculitis)

11. Case One, Question 2
Which of the following history and clinical items are commonly found in patients with EN?
Patient is female
Recent fever
Recent upper respiratory infection
Use of oral contraceptives
All of the above

12. Case One, Question 2 Answer: e
Which of the following history and clinical items are commonly found in patients with EN?
Patient is female
Recent fever
Recent upper respiratory infection
Use of oral contraceptives
All of the above

13. EN: The Basics
Can occur at any age, but most cases appear between 2nd and 4th decades
15-20x more common in women than men
EN is not a disease, but a reaction pattern to a variety of factors including infections, medications, and systemic diseases
Diagnosis of EN should always be followed by a search for the underlying etiology
Streptococcal disease is the most common cause of EN in children
Drugs, sarcoidosis, and inflammatory bowel disease (IBD) are commonly associated disorders in adults with EN

14. Conditions Associated with EN
Idiopathic > 50%
Infections
Streptococcal infections, tuberculosis, histoplasmosis, coccidiomycosis
Drugs
Oral contraceptive pills, sulfonamides
Neoplasms
Lymphoma, leukemia, renal cell carcinoma
Miscellaneous Conditions
Sarcoidosis, inflammatory bowel disease
Note: Only a few common causes of EN are mentioned. EN is associated with a wide variety of disease processes and medications.

15. Case One, Question 3
Which of the following statement regarding treatment of EN is true?
Antihistamines are often used for treatment
Anti-inflammatories should be avoided
EN tends to be self-limited
Systemic steroids are of no value

16. Case One, Question 3 Answer: c
Which of the following statement regarding treatment of EN is true?
Antihistamines are often used for treatment (Not true)
Anti-inflammatories should be avoided (Not true. Anti- inflammatories are often used in the treatment of EN)
EN tends to be self-limited
Systemic steroids are of no value (Not true. Systemic steroids can be used if underlying infection and malignancy have been excluded)

17. EN: Treatment
EN is usually self-limited or resolves with treatment of the underlying disorder
Lesions heal without atrophy or scarring
Eruption generally lasts from 3 to 6 weeks, and recurrences are frequent
Treatment is typically symptomatic
Supportive measures and pain control are recommended
The use of systemic glucocorticoids should be weighed against the possibility of masking an underlying neoplastic, inflammatory, or infectious condition
Oral potassium iodide therapy is another treatment option

18. Case Two
Ms. Beverly Prescott

19. Case Two: History
HPI: Ms. Prescott is a 35-year-old woman who presents to her primary care provider with tender red nodules on her anterior shins. Some of the lesions appear to be resolving, but others are still appearing. No sick contacts or anyone else with a rash.
PMH: no major illnesses or hospitalizations
Allergies: none
Meds: oral contraceptive pills (unable to recall the name)
Family history: father with history of BCC
Social history: lives with a friend in an apartment, works in advertising
Health-related behaviors: alcohol use (1-2 drinks per week), no tobacco or drug use
ROS: negative ’

20. Case Two: Exam Vital Signs: normal HEENT: normal exam
Lungs: clear to auscultation
Skin: multiple scattered shiny, erythematous nodules on the anterior lower extremities

21. Case Two, Question 1
The primary care provider suspects erythema nodosum. What else should be considered as part of the initial evaluation?
Make sure a thorough medical history and review of systems was performed
Order an ASO
Place a PPD
All of the above

22. Case Two, Question 1 Answer: d
The primary care provider suspects erythema nodosum. What else should be considered as part of the initial evaluation?
Make sure a thorough medical history and review of systems was performed
Order an ASO
Place a PPD
All of the above

23. Case Two, Question 2
What is the likely cause of Ms. Prescott’s erythema nodosum?
Crohn’s disease
Oral contraceptives
Sarcoidosis
Tuberculosis

24. Case Two, Question 2 Answer: b
What is the likely cause of the Ms. Prescott’s erythema nodosum?
Crohn’s disease (Possible that EN is the presenting feature of IBD, but her OCP use is a more likely cause in this case)
Oral contraceptives
Sarcoidosis (Possible, but less likely)
Tuberculosis (No known risk factors, but a PPD placement would be prudent)

25. Case Three
Ms. Maria Ojeda

26. Case Three: History
HPI: Ms. Ojeda is a 50-year-old woman who presents to the general medicine clinic with tender red nodules on her posterior calves for the past 2 months.
PMH: last visit to the doctor was 10 years ago, no major illnesses or hospitalizations
Medications: none
Allergies: none
Family history: mother with hypertension
Social history: lives with multiple family members in the city, recently moved to the US from Guatemala
Health-related behaviors: no tobacco, alcohol, or drug use
ROS: occasional fatigue

27. Case Three: Exam Vital signs: normal
Physical exam normal except for: tender erythematous shiny nodules on the posterior calves bilaterally

28. Case Three, Question 1 What is the most likely diagnosis?
Erythema induratum
Erythema nodosum
Polyarteritis nodosa
Syphilitic gumma

29. Case Three, Question 1 Answer: a What is the most likely diagnosis?
Erythema induratum
Erythema nodosum (Characterized by painful, erythematous, non-ulcerative nodules usually located on anterior lower legs)
Polyarteritis nodosa (Characterized by painful, subcutaneous nodules. Livedo reticularis may be present)
Syphilitic gumma (Painless subcutaneous nodules, enlarge, attach to the overlying skin, and eventually ulcerate)

30. Erythema Induratum
Erythema induratum is a panniculitis characterized by tender subcutaneous nodules usually located on the lower posterior calf
Erythema induratum is chronic and more commonly affects middle-aged women
Occurs in the setting of tuberculosis (latent)
PPD will usually be positive
Lesions can resolve spontaneously with or without ulceration and often heal with scarring

31. When to Biopsy Panniculitis
For persistent lesions (> 6wks) or when the diagnosis is unclear a biopsy is typically necessary and these patients should be referred to a dermatologist
A deep incisional or excisional biopsy should be obtained for best visualization because a punch biopsy is likely to produce an inadequate sample

32. Take Home Points
EN is characterized by painful, erythematous, non- ulcerative subcutaneous nodules.
Most cases appear between the 2nd and 4th decade of life and is more common in women.
There are numerous etiologies for EN including infections, medications, neoplasms, and other miscellaneous conditions.
Streptococcal infection is the most common etiologic factor in children.

33. Take Home Points
Drugs, sarcoidosis, systemic fungal infections (coccidiomycosis, histoplasmosis) and inflammatory bowel disease are commonly associated disorders in adults with EN.
EN tends to be self-limited or resolves with treatment of the underlying disorder.
Erythema induratum can be distinguished from EN by the chronic time course, location on the posterior calf, ulceration of the lesions and association with latent tuberculosis.

34. Acknowledgements
This module was developed by the American Academy of Dermatology Medical Student Core Curriculum Workgroup from
Primary authors: Sarah D. Cipriano, MD, MPH; Eric Meinhardt, MD; Timothy G. Berger, MD, FAAD.
Peer reviewers: Peter A. Lio, MD, FAAD; Carlos Garcia, MD.
Revisions and editing: Sarah D. Cipriano, MD, MPH; Jillian W. Wong. Last revised March 2011.

35. References
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James WD, Berger TG, Elston DM, “Chapter 16. Mycobacterial Disease” (chapter). Andrews’ Diseases of the Skin Clinical Dermatology. 10th ed. Philadelphia, Pa: Saunders Elsevier; 2006: 337.
James WD, Berger TG, Elston DM, “Chapter 23. Diseases of Subcutaneous Fat” (chapter). Andrews’ Diseases of the Skin Clinical Dermatology. 10th ed. Philadelphia, Pa: Saunders Elsevier; 2006:
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