Skin signs of systemic disease Flashcards
Type 1 allergy, Neurofibromatosis Type 1, Tuberous sclerosis, Erythema multiforme, Erythema Nodosum
1
Q
What is a Type 1 allergy?
A
Immediate IgE-mediated reaction within minutes to 2 hours of allergen exposure
2
Q
What are the common routes of allergen exposure?
A
- Skin contact
- inhalation
- ingestion
- injection
3
Q
What happens in the sensitisation stage?
A
B cells produce IgE, which binds to mast cells
4
Q
What happens in the allergic stage?
A
Allergen binds to IgE-coated mast cells, triggering degranulation and histamine release
5
Q
What are the skin symptoms of Type 1 allergy?
A
(1) Urticaria (itchy wheals)
(2) Angioedema (non-itchy swelling
6
Q
What are the GI symptoms?
A
Nausea, vomiting, diarrhea, colicky pain
7
Q
What are the respiratory symptoms?
A
Nasal itching, sneezing, rhinorrhea, wheezing/asthma
8
Q
What is anaphylaxis?
A
Severe life-threatening allergic reaction affecting
1. airway
2. breathing
3. circulation
9
Q
What is the most important investigation for type 1 allergy?
A
History – consistent reaction with every exposure
10
Q
What test confirms anaphylaxis?
A
Serum mast cell tryptase
11
Q
What is the first-line treatment for long-term management?
A
Allergen avoidance and antihistamines
12
Q
When is an adrenaline autoinjector needed?
A
For anaphylaxis- Doses:
300µg (adults) = only for lower body weight or certain autoinjectors
Usually 500
150µg (children) = under 6
300 µg = 7-12 years
2 pens prescribed
13
Q
What is the 3-step plan for acute allergic reactions?
A
(1) Give chlorphenamine at first sign.
(2) If it worsens within 30 minutes, seek help and give prednisolone.
(3) If collapse/blue, give adrenaline IV and call 999
14
Q
What is the adult dose of adrenaline for anaphylaxis?
A
500µg (0.5mg) IM in the anterolateral thigh, repeat every 5 minutes if needed
15
Q
What is the dose of adrenaline for a 7 year-old child in anaphylaxis?
A
300 micrograms (1:1000) IM; dose for children aged 6-12
16
Q
What is Neurofibromatosis Type 1 (NF1)?
A
A genetic condition causing tumors along the nervous system
17
Q
What gene mutation causes NF1?
A
Mutation in the NF1 gene
18
Q
What skin feature is common in NF1?
A
Café au lait macules
(pigmented skin spots)
19
Q
What are neurofibromas?
A
Benign nerve tumors, also called “buttonhole lesions”
20
Q
What is a plexiform neuroma?
A
A diffuse neurofibroma that can affect larger nerve areas
21
Q
Where does freckling occur in NF1?
A
Axillary (armpit) or inguinal (groin) areas
22
Q
What are Lisch nodules?
A
Pigmented iris hamartomas, seen in NF1
23
Q
What eye condition is associated with NF1?
A
Optic glioma (tumor of the optic nerve)
24
Q
What type of bone abnormalities occur in NF1?
A
Distinctive bony lesions, such as scoliosis or tibial dysplasia
25
What type of genetic inheritance does Tuberous Sclerosis follow?
Autosomal dominant
= new mutations are common
26
Which genes are associated with Tuberous Sclerosis?
TSC1 (chromosome 9q34)
TSC2 (chromosome 16p13.3)
27
What is the earliest cutaneous sign of Tuberous Sclerosis?
Ash-leaf macules
= hypopigmented patches
28
What type of seizures can be an early sign of Tuberous Sclerosis?
Infantile seizures (common early presentation)
29
What are the characteristic facial lesions in Tuberous Sclerosis?
Facial angiofibromas in a butterfly distribution
30
What are Shagreen patches?
Thickened, leathery skin patches seen in Tuberous Sclerosis
31
Which organs are commonly affected by hamartomas in Tuberous Sclerosis?
Brain, heart, lungs, kidneys
32
What is a common dental sign of Tuberous Sclerosis?
Enamel pitting
33
What nail abnormality is associated with Tuberous Sclerosis?
Periungual fibromas
34
Common cutaneous features in tuberous sclerosis are what?
(1) Ash-leaf spots
(2) Shagreen patches
= thickened skin with an 'orange-peel appearance' most commonly seen over the lower back.
(3) Angiofibromas
= small reddish bumps seen over the nose and cheeks in a butterfly distribution
(4) Subungual fibromata
35
The abnormal repetitive movements are suggestive of infantile spasms. This relates to what disease?
Tuberous sclerosis
36
What is the management for tuberous sclerosis?
Supportive, with monitoring and treating complications such as epilepsy
37
What are the diseases involved in reactive eruptions?
Erythema multiforme
Erythema nodosum
37
What is the characteristic morphology of Erythema Multiforme?
Target (Iris) lesions
38
What is the most common infectious cause of Erythema Multiforme?
Herpes Simplex Virus (HSV)
39
Which other infections can trigger Erythema Multiforme?
Tuberculosis, Streptococcus, Mycoplasma
40
Which drugs are commonly associated with Erythema Multiforme?
Sulphonamides
penicillin
carbamazepine
allopurinol
NSAIDs
oral contraceptive pill
41
How long do lesions from erythema nodosum typically last?
2-6 weeks
42
What systemic symptoms accompany erythema nodosum?
Fevers, arthralgia, malaise
43
When is the peak incidence of erythema multiforme?
Individuals aged 20s-30s
44
What is erythema multiforme, which is when the eyes and mucosal surfaces are involved?
Stevens-Johnsons syndrome
45
A 27-year-old man attends the GP complaining of a rash. He first noticed the rash yesterday on his hands and feet before it spread up his arms and legs to his trunk.
On examination there several well-defined circular papules on his skin, some of which have evolved to form a target-shaped lesion of three concentric rings of different colours. Examination of his mouth reveals no abnormalities.
What does this man have and what is the most likely cause of his condition?
erythema multiforme
= HSV
46
A 26-year-old man presented to his GP with an itchy red rash on his hands. He reported attending the GP only a week ago and received a course of antibiotics to treat tonsillitis. On examination, the rash consists of circular oedematous papules that are pale and spreading. They are yellow in the center and pink around the edge.
Given the history and examination findings, what is the most likely diagnosis?
Erythema multiforme
47
A 25-year-old male presents to the GP with a new rash which has appeared suddenly since this morning. He is fit and well but reports having a cold sore on his lip a week ago. On examination, there are multiple well-demarcated skin lesions over his face, neck and trunk. There are no lesions on his mucosal surfaces.
How would you describe this lesion?
Target
= Erythema multiforme
47
What are the clinical features of Erythema Nodosum?
Red, tender, diffuse nodules that may be associated with joint pains and fever
48
Where are Erythema Nodosum nodules typically located?
Over the shins
49
How long does it take for Erythema Nodosum to resolve?
6-8 weeks, resembling a bruise
50
What infections can cause Erythema Nodosum?
(1) Streptococcus
(2) Tuberculosis
(3) Epstein-Barr Virus (EBV)
(4) Fungal infections
51
Which drugs are commonly associated with Erythema Nodosum?
Oral contraceptive pills (OCP) and sulphonamides
52
Which inflammatory conditions can lead to Erythema Nodosum?
Inflammatory bowel disease (IBD) and sarcoidosis
53
A 50-year-old woman presents to her GP with a three-week history of a cough. This was initially productive of dark sputum but recently she has noticed a small amount of blood when she coughs. She has also had intermittent fevers, night sweats and some unintentional weight loss. On further questioning, the patient mentions that she returned from a trip to Bangladesh three months ago. Urgent blood tests and imaging are arranged and she is found to be positive for tuberculosis (TB).
What skin condition is most associated with TB?
Erythema nodosum
54
What is the key difference in the appearance of Erythema Nodosum and Erythema Multiforme?
Erythema nodosum presents as red, tender nodules
= typically on the shins
Whilst erythema multiforme presents as target-shaped lesions
= commonly on palms, soles, and elbows
55
A 6-year-old boy is brought into the GP surgery by his mother who has noticed an odd rash on his body
On examination, there are 7 oval-shaped, coffee-coloured patches across his body and freckling in his axillae. You notice his irises appear unusual- they are blue with brown patches
What is a common complication of this disease?
Optic glioma
= This patient has NF1, as evidenced by the 7 cafe-au-lait spots, axillary freckling and Lisch nodules in the eyes
56
A 26-year-old woman has been referred to the dermatology clinic with a 4-week history of skin rash.
Past medical history includes mild asthma. Regular medications include folic acid 400 micrograms OD and over-the-counter vitamin supplements due to pregnancy.
She feels well in herself but states she had a mild cold when the lesions first developed.
On examination, she has multiple, discrete, raised erythematous lesions on the arms and legs ranging from 8cm in diameter to 12cm in diameter. There is pain on active and passive joint movement.
What is the likely diagnosis?
Erythema nodosum
= Erythema nodosum may be caused by pregnancy
57
A 24-year-old woman presented at 15 weeks gestation with a 1-week history of erythematous, tender lesions on the pretibial aspects of both legs. The patient reported having had a 'flu-like' illness with fever, a sore throat and dry cough while these lesions developed. The 'flu' symptoms resolved within 10 days without medical intervention, but the lesions on her legs persisted. An initial antistreptolysin-O titre was raised.
What is the most likely diagnosis in this case?
Erythema nodosum can be caused by streptococcal infection
57
An 8-year-old boy presented with a painless swelling on the superotemporal aspect of his orbit. It was smooth on examination and produced no visual disturbances.
Following excision, it was found to be lined by squamous epithelium and hair follicles. What lesions most closely matches these findings?
Dermoid cyst
58
A person presents with erythema nodosum.
Rank the order of the most likely reason she got it.
(1) Pregnancy / Oral contraceptive use
(2) Sarcoidosis
(3) Drugs (eg, penicillin, sulphonamides)
(4) Streptococcal infection
(5) Inflammatory bowel disease
(6) Tuberculosis
(7) Other infections (eg, Mycoplasma, EBV, Yersinia)
(8) Behçet’s disease
(9) Idiopathic
59
What is the most important test to do in erythema nodosum is what?
Chest x-ray
= to rule out sarcoidosis and tuberculosis
60
A 29-year-old woman presents to her GP with several painful, red, raised lesions on her shins. She has also noted a thin, white, odourless vaginal discharge.
Over the last week, she has suffered from feeling increasingly nauseous. She has also been passing urine more frequently but denies dysuria/haematuria.
(A) What is this disease and why?
(B) What is the most appropriate next investigation?
Erythema nodosum
(1) Painful red nodules on the shins
= classic symptom
(2) Thin, white, odourless vaginal discharge
= normal in pregnancy
Pregnancy test
61
A 35-year-old female presents with tender, erythematous nodules over her forearms. Blood tests reveal:
Calcium 2.78 mmol/l
What is the most likely diagnosis?
Erythema nodosum
62
How is erythema multiforme caused?
hypersensitivity reaction cased by an infection
63
A 34-year-old man comes to his GP for review. Over the past two weeks, he has developed several painful, erythematous lesions on his shins. He has no dermatological history of note and is usually fit and well. On examination, the lesions are consistent with erythema nodosum. You arrange some baseline investigations.
What is the most appropriate management?
No active treatment, arrange routine follow-up
64
What combination of tests would be most useful to investigate in a patient who has erythema nodosum?
Serum ACE = possible sarcoidosis
Sputum culture = TB: gold standard test
Chest x-ray = TB + sarcoidosis
65
A 30-year-old man cuts the corner of his lip whilst shaving. Over the next few days, a large purplish lesion appears at the site which bleeds on contact.
What is this?
Pyogenic granuloma
66
What disease is most characteristic of Mycoplasma pneumoniae?
Erythema multiforme
67
What condition causes target-like lesions, often after infections or medications, and may involve the mucous membranes?
Erythema multiforme
68
What neurofibromatosis type is associated with bilateral vestibular schwannomas?
2
69
Axillary freckles are indicative of what?
Neurofibromatosis type 1
