Rashes due to systemic diseases: Erythema nodosum, Pyoderma gangrenosum, Necrobiosis lipodica, Granuloma annulare, CLE, Erythema multiforme

Question 1

What is erythema nodosum?

Answer 1

Acute erythematous nodular eruption from skin due to inflammation of subcutaneous fat

It is a skin condition characterized by painful, red nodules, primarily on the lower legs.

Question 2

What type of hypersensitivity reaction is associated with erythema nodosum?

Answer 2

Delayed type 4 hypersensitivity reaction

This reaction is often linked to underlying systemic diseases.

Question 3

What percentage of erythema nodosum cases have no identifiable cause?

Answer 3

60%

This indicates that in many cases, the underlying cause remains unknown.

Question 4

Name three drug classes that can cause erythema nodosum.

Answer 4

• NSAIDs
• Bromides
• Sulfonamides

Other drugs like iodides, penicillins, and salicylates can also be implicated.

Question 5

List three systemic diseases associated with erythema nodosum.

Answer 5

• SLE (Systemic Lupus Erythematosus)
• Sarcoidosis
• Crohn disease

Ulcerative colitis is also associated.

Question 6

Which malignancies are linked to erythema nodosum?

Answer 6

• Lymphoma
• Renal cell carcinoma
• Leukaemia

These cancers can contribute to the development of the condition.

Question 7

Name two types of microbiological infections that can cause erythema nodosum.

Answer 7

• TB (Tuberculosis)
• Viruses

Other infections include leprosy, deep fungal infections, and group A strep.

Question 8

Describe the appearance of erythema nodosum nodules.

Answer 8

Erythematous, non-scarring, oval nodules that begin as light red then become darker and bruised

They typically have a symmetrical distribution.

Question 9

Where on the body are erythema nodosum nodules most commonly found?

Answer 9

On shins, knees, ankles

However, they can occur anywhere on the body.

Question 10

What are some associated symptoms of erythema nodosum?

Answer 10

• Fever
• Malaise
• Arthralgia

These symptoms often indicate an underlying illness.

Question 11

What is the primary method of diagnosing erythema nodosum?

Answer 11

Clinical diagnosis

Investigations may include throat swabs and imaging tests.

Question 12

Which test is used to identify streptococcal infection in erythema nodosum cases?

Answer 12

Streptolysin (ASO) titre

This test helps determine if a streptococcal infection is present.

Question 13

What is the recommended initial management for erythema nodosum?

Answer 13

RICE and analgesia (e.g., NSAIDs)

RICE stands for Rest, Ice, Compression, Elevation.

Question 14

True or False: Erythema nodosum usually resolves spontaneously within weeks to months.

Answer 14

True

Treatment should also focus on addressing the underlying cause.

Question 15

What is pyoderma gangrenosum?

Answer 15

It is an ulcerative autoinflammatory disorder that is a form of neutrophilic dermatoses.

Question 16

Who does pyoderma gangrenosum usually affect?

Answer 16

It usually affects adults, not children.

Question 17

What are common associations in the pathophysiology of pyoderma gangrenosum?

Answer 17

It can be idiopathic but is usually associated with inflammatory disorders, haematological disorders, immunodeficiencies, drugs, and history of trauma or surgery.

Question 18

What inflammatory disorders are associated with pyoderma gangrenosum?

Answer 18

Inflammatory bowel disease (IBD) and inflammatory arthritis.

Question 19

What haematological disorders are associated with pyoderma gangrenosum?

Answer 19

Myeloproliferative disorders (commonly AML), myelodysplastic syndromes (MDS), and monoclonal gammopathy of undetermined significance (MGUS).

Question 20

What immunodeficiency is associated with pyoderma gangrenosum?

Answer 20

HIV infection.

Question 21

What drugs are associated with pyoderma gangrenosum?

Answer 21

Cocaine, isotretinoin, and propylthiouracil (for hypothyroidism).

Question 22

What is the typical presentation of pyoderma gangrenosum?

Answer 22

Painful, rapidly growing, irregularly-shaped papules or pustules that develop into large purulent ulcers with a grey-purple border and surrounding erythematous rim.

Question 23

Where are pyoderma gangrenosum lesions usually located?

Answer 23

They are usually located on the lower extremities.

Question 24

What is the hallmark of healing in pyoderma gangrenosum?

Answer 24

Healing leaves hallmark cribriform scarring, which is a criss-cross pattern.

Question 25

How are lesions classed in pyoderma gangrenosum?

Answer 25

Lesions are classed as pustular, vesiculobullous, ulcerative, or vegetative.

Question 26

What are the Maverakis criteria for pyoderma gangrenosum?

Answer 26

It includes 1 major criterion (histopathology of ulcer edge shows neutrophil infiltrate) and several minor criteria.

Question 27

What investigations are done for pyoderma gangrenosum?

Answer 27

Charcoal swab sample of ulcer to identify microorganisms, biopsy to rule out other ulcerative causes, and tests to screen for underlying disease.

Question 28

What is the primary management for pyoderma gangrenosum?

Answer 28

Primarily treat the underlying cause, with dermovate or calcineurin inhibitor around ulcer edges and keep the wound dressed and clean.

Question 29

What is the first-line treatment for pyoderma gangrenosum?

Answer 29

Systemic therapy with corticosteroids and/or immunosuppressants.

Question 30

What is the second-line treatment for pyoderma gangrenosum?

Answer 30

Infliximab.

Question 31

What is Necrobiosis lipoidica?

Answer 31

A chronic skin condition associated with diabetes, usually type 1. ## Footnote More common in females than males and in young or middle-aged individuals.

Question 32

What is the pathophysiology of Necrobiosis lipoidica?

Answer 32

Usually associated with diabetes but can also be linked to other metabolic and autoimmune disorders, such as rheumatoid arthritis.

Question 33

What is the presentation of Necrobiosis lipoidica?

Answer 33

Initially presents as well-demarcated red-brown-yellow plaques that progress to yellow-brown, shiny, waxy lesions with telangiectasia. ## Footnote Commonly distributed symmetrically on shins and pretibial skin.

Question 34

How long do lesions from Necrobiosis lipoidica last?

Answer 34

They can last for several months before resolution, healing slowly.

Question 35

What is the management for Necrobiosis lipoidica?

Answer 35

Treatment includes potent steroid cream or calcineurin inhibitors like Tacrolimus or cyclosporin, along with monitoring diabetic control.

Question 36

What is Granuloma annulare?

Answer 36

A benign skin condition characterized by papules that form a ring with a normal or sunken center.

Question 37

What is the presentation of Granuloma annulare?

Answer 37

Initially presents as a small ring of flesh-colored or pink papules that merge to form a large annular, non-scaly, shiny plaque with a paler, sunken center. ## Footnote Commonly found on the lateral and dorsal surfaces of hands and feet.

Question 38

What are the main classifications of Granuloma annulare presentation?

Answer 38

1. Localised: Usually confined to joints, more common in children and young adults, associated with Hashimoto's thyroiditis. 2. Generalised/disseminated: Widespread, symmetrical, and bilateral annular patches or papules that are pink or flesh-colored.

Question 39

What is Cutaneous Lupus Erythematosus (CLE)?

Answer 39

A form of Lupus Erythematosus that is confined to skin.

Question 40

What is the typical age of onset for CLE?

Answer 40

Typically in the 30-40s.

Question 41

Is CLE more common in males or females?

Answer 41

More common in females than males.

Question 42

What genetic predispositions are associated with CLE?

Answer 42

HLA-B88, TREX1, SAMHD1.

Question 43

What factors contribute to the pathophysiology of CLE?

Answer 43

Combination of genetic and environmental factors, with an autoimmune response to unknown antigen or UV sunlight.

Question 44

How does UV exposure affect CLE?

Answer 44

Antibodies and immune complexes infiltrate the dermoepidermal junction in response to UV exposure, causing tissue damage and inflammation.

Question 45

What drugs are associated with drug-induced CLE?

Answer 45

Smoking, PPIs, hydrochlorothiazide, procainamide, hydralazine, quinidine, isoniazid.

Question 46

Can CLE progress to SLE?

Answer 46

Yes, if the patient develops lung and renal involvement.

Question 47

What are the four subtypes of CLE?

Answer 47

1. Acute CLE 2. Subacute CLE 3. Chronic CLE 4. Drug-induced CLE.

Question 48

What characterizes Acute CLE?

Answer 48

Malar rash in a butterfly pattern over the nose bridge and malar region, sparing the nasolabial folds, with transient lesions lasting several hours to days.

Question 49

What are the forms of Subacute CLE?

Answer 49

Annular form and Papulosquamous form.

Question 50

What is the appearance of the Annular form of Subacute CLE?

Answer 50

Pink/red annular, pruritic patches that coalesce into larger patches on sun-exposed areas.

Question 51

What is the appearance of the Papulosquamous form of Subacute CLE?

Answer 51

Small pink/red, pruritic patches with scaling in sun-exposed areas.

Question 52

What characterizes Chronic CLE?

Answer 52

Discoid lupus is the most common form, with disc-shaped or annular red/purple lesions that heal with scarring.

Question 53

What is the hallmark sign of Chronic CLE?

Answer 53

'Carpet tack' sign due to follicular plugging.

Question 54

What is the gold standard for investigating CLE?

Answer 54

Skin biopsy with immunofluorescence.

Question 55

What will a skin biopsy show in CLE?

Answer 55

Hallmark histopathological features of each subtype.

Question 56

What is the Cutaneous Lupus Erythematosus Disease Area and Severity Index (CLASI) management for topicals?

Answer 56

Very potent corticosteroid creams or calcineurin inhibitors.

Question 57

What are the oral management options for Cutaneous Lupus Erythematosus?

Answer 57

Steroids, immunosuppressants such as Hydroxychloroquine, methotrexate, and MMF.

Question 58

What is erythema multiforme?

Answer 58

An immune-mediated, self-limiting mucocutaneous reaction to medications or infections.

Question 59

What is the epidemiology of erythema multiforme?

Answer 59

More common in males than females; most common in children, adolescents, and adults under 40 years old.

Question 60

What are some infective causes of erythema multiforme?

Answer 60

HSV, EBV, cytomegalovirus.

Question 61

What drugs are associated with erythema multiforme?

Answer 61

Anticonvulsants and NSAIDs.

Question 62

What is the typical presentation of erythema multiforme?

Answer 62

Well-demarcated, circular red/pink papules that enlarge into ringed-plaques (target lesions) with burning or itching sensation.

Question 63

What characterizes EM target/iris lesions?

Answer 63

They have 3 concentric zones: dark red centre, pink middle zone, red outer ring.

Question 64

Where is the symmetrical distribution of erythema multiforme typically found?

Answer 64

On distal extremities (palms and soles) and face, then diffuses proximally.

Question 65

Is mucosal involvement common in erythema multiforme?

Answer 65

It is uncommon but usually limited to oral mucosa, causing swollen lips and haemorrhagic crusting.

Question 66

Are prodromal symptoms common in erythema multiforme?

Answer 66

It is rare to have prodromal symptoms such as fever and malaise.

Question 67

What are the two classes of erythema multiforme?

Answer 67

1. EM minor: without/with mild mucosal involvement and without systemic symptoms. 2. EM major: with severe mucosal involvement and with systemic symptoms.

Question 68

How is erythema multiforme diagnosed?

Answer 68

Clinical diagnosis.

Question 69

What is the management for erythema multiforme?

Answer 69

Resolves spontaneously within 3-5 weeks; withdraw offending drug or treat infective cause.

Question 70

What is the management for mild cases of erythema multiforme?

Answer 70

Oral antihistamines and mildly-potent topical corticosteroids.

Question 71

What is the management for recurrent or severe cases of erythema multiforme with mucosal involvement?

Answer 71

Prednisolone, cyclosporine, or azathioprine.

Question 72

What is the management for herpes-associated erythema multiforme?

Answer 72

Continuous acyclovir.