Impetigo: Impetigo is a common condition. It most often affects children although it can occur at any age.

Risk factors : Include poor hygiene and skin conditions that lead to a break in the protective layers.

Types and presentation:

• Non-bullous impetigo : Non-bullous lesions usually start as tiny pustules or vesicles that evolve rapidly into honey-colored crusted plaques that tend to be under 2 cm in diameter. It is usually on the face (particularly around the mouth and nose)

• Bullous impetigo : Bullous lesions have a thin roof and tend to rupture spontaneously. They are usually on the face, trunk, extremities, buttocks, or perineal regions. They are more likely to occur on top of other diseases like atopic eczema.

Ecthyma : This begins as a non-bullous impetigo but ulcerates and becomes necrotic. It is deeper and may occur with lymphadenitis.

Treatment summary:

1. Topical fusidic acid

2. Topical Mupirocin if MRSA is involved

3. Systemic antibiotics namely flucloxacillin (or clarithromycin) in resistance to topical treatment.

Other options :

Contact Dermatitis: Usually presents with itching and redness of a single affected area.

Chickenpox: Presents with systemic symptoms such as pyrexia, and malaise. Vesicles present on the face, neck, and trunk.

Measles: Koplik spots, Cough, Conjunctivitis, Coryza.

Erythema nodosum is the most likely diagnosis here. The reason they give a history of coming from India with fever and feeling of being unwell is to point you towards the direction of tuberculosis. Erythema nodosum can occur with the primary infection of TB.

This man is suffering from urticaria. Oral antihistamines would be indicated. Since this is an allergic reaction, the only two reasonable options are A and C in this question. However, in the context of allergic reactions, IM adrenaline should only be used in anaphylactic shock whereby the patient would have breathing difficulties.

The following are the indications of adrenaline in anaphylaxis:

1. Hoarseness of voice

2. Wheeze

3. Shortness of breath

4. Shock

5. Stridor

6. Swelling of the tongue and cheek

7. Facial swelling

If you see an urticaria like allergic reaction, with none of the following indications stated above for adrenaline, then pick the oral antihistamine as the answer.

If there was a choice to pick a non-sedating antihistamine (e.g. cetirizine or loratadine), pick it over a sedating antihistamine (e.g. chlorpheniramine) unless there was a reason to pick a sedating antihistamine e.g. difficulty sleeping.

Molluscum contagiosum (pox virus) are white or pink papules with an umbilicated (depressed) central punctum. They may be found anywhere on the skin.

They resolve spontaneously but can take around 6 to 24 months. If squeezed, they produce a cheesy material. They usually affect children.

They are also especially seen in patients with decreased immunity and so if a patient presents with extensive pink umbilicated papules, consider AIDS.

Remember these two typical groups of patients when thinking of molluscum contagiosum:

1. Children

2. HIV.

The majority of urticarial wheals tend to last less than 24 hours. New lesions would tend to appear within hours or days. They are intensely itchy.

Acute urticaria – “Here today and gone tomorrow”

Aspirin is one of the medications that could elicit an episode of urticaria by causing direct release of histamine from mast cells. Other medications that could result in direct release of histamine include opiates.

The diagnosis here is psoriasis. The stem mentions the presence on the extensor surfaces and a familial predisposition. Therefore the correct answer is to tell her that the rash is not contagious and reassure her.

Note: Scabies arise on the flexor surfaces and very rarely on the extensor surfaces.

PSORIASIS :

• Itchy, well-demarcated circular-to-oval bright red/pink elevated lesions (plaques) with overlying white or silvery scale, distributed symmetrically over extensor body surfaces and the scalp.

• Nail changes: pitting, onycholysis

• Relapses

• May have a family history.

The lesion in this stem describes a target lesion. This is consistent with erythema multiforme. Mycoplasma pneumoniae, which is the likely pathogen that she has been infected with, is one of the common pathogens known to cause erythema multiforme.

Atopic eczema usually begins between ages 3 and 12 months and usually starts on the scalp and face. As they get older, it may localize in the flexures. If flare-ups of atopic eczema occur, then corticosteroids are effective in controlling and suppressing symptoms in most cases.

Topical corticosteroids for atopic eczema should be prescribed for application only once or twice daily as long-term use of topical steroids may result in skin atrophy, striae, and telangiectasia.

During topical steroids, he should continue to use emollients regularly. Any physiological or emotional stressor can cause a flare-up of eczema as well as a variety of environmental factors, temperature, and diet.

This child has atopic dermatitis or eczema. Children often have skin flexures involved.

Emollients form the basis of eczema management and should be used as the first line. It should be used at least twice a day and after a bath even when eczema is under control. Topical steroids are used as the second line. They are especially useful during flare-ups after trying emollients first. Hydrocortisone is considered a mild topical steroid and clobetasone is considered a very potent topical steroid.

Fusidic acid is a topical antibacterial preparation. Clotrimazole is a topical antifungal agent. It is used for athlete’s foot, fungal groin infections, and in fungal nappy rash.

The clues for basal cell carcinoma in the exam are descriptions of a pearly white umbilicated ulcer with central depression anywhere in the face with rolled edges or inverted edges. These are hints pointing towards the diagnosis of basal cell carcinoma. Ulcers presenting above the neck in the exam are almost inevitably basal cell carcinoma.

BASAL CELL CARCINOMA:

Basal cell carcinomas are slow-growing, locally invasive malignant epidermal skin tumours.

Risk factors:

• Genetic predisposition

• Exposure to ultraviolet radiation

Presentation:

• The sun-exposed areas of the head and neck are the most commonly involved sites

• Early lesions are often small, translucent, or pearly and have raised areas with telangiectasia

• Indurated edge and ulcerated center.

Please see Q-10

Cellulitis is an infection of the dermis and subcutaneous tissue. The most common causative organisms are Streptococcus or Staphylococcus spp. but they can be caused by a wide range of both aerobic and anaerobic bacteria. Flucloxacillin in adults is usually given as the first line in uncomplicated infection.

In sufficient doses, this covers both beta-hemolytic streptococci and penicillinase-resistant staphylococci. Erythromycin or Clindamycin can be used if the patient is penicillin-allergic.

Cetirizine is a second-generation antihistamine. Its use will help reduce the symptoms of the pruritus. Second-generation antihistamines like cetirizine are less able to cross the blood-brain barrier and therefore have diminished effects on the central nervous system and thus less likely to cause drowsiness when compared to first-generation antihistamines like chlorpheniramine.

Corticosteroids have very little use in urticarial rashes. There may be times when steroids are used but it usually involves severe cases and the suspicion of rarer forms of urticaria such as urticarial vasculitis.

ACNE ROSACEA :

Rosacea is a common rash, usually occurring on the face, which predominantly affects middle-aged and fair skinned people.

Clinical features:

• Red papules and pustules on the nose, forehead, cheeks and chin

• Frequent blushing or flushing

• Red face due to persistent redness and/or prominent blood vessels - telangiectasia

• Aggravation by sun exposure and hot and spicy food

• Fibrous thickening causing rhinophyma  

If a topical steroid is also being used with an emollient, the emollient should be applied first followed by waiting at least 30 minutes before applying the topical steroid. Creams soak into the skin faster than ointments.

Cellulitis is usually caused by gram-positive bacteria such as staphylococci or streptococci which are commonly present on the skin. Flucloxacillin is a narrow-spectrum beta-lactam antibiotic that covers susceptible Gram-positive bacteria and should therefore be given.

COMMON ANTIMICROBIALS :

This is a list of drugs for common conditions in the exam 

• Mild community-acquired pneumonia : Amoxicillin

• Moderate community-acquired pneumonia : Amoxicillin + clarithromycin

• Severe community-acquired pneumonia : Co-amoxiclav+clarithromycin

• Hospital-acquired pneumonia :

• Pneumocystis jirovecii pneumonia : Co-trimoxazole

• Tuberculosis : 8 weeks of rifampicin, pyrazinamide, and ethambutol followed by 16 weeks of rifampicin and isoniazid

• Aspiration pneumonia : Amoxicillin + metronidazole 

• Meningitis : Ceftriaxone

• Listeria meningitis : Ceftriaxone+ampicillin+gentamicin

• Meningitis prophylaxis : Rifampicin or ciprofloxacin

• Cryptococcal meningitis : Amphotericin B 

• Lower uncomplicated UTI in non-pregnant women : Trimethoprim or nitrofurantoin

• Candida albicans : Clotrimazole or fluconazole

• Trichomonas vaginalis : Metronidazole

• Bacterial vaginosis : Metronidazole

• Cervicitis (Gonorrhoea and Chlamydia) : Ceftriaxone and azithromycin

• Syphilis: Penicillin G

• Genital herpes : Acyclovir 

• Salmonella/Shigella/Campylobacter : Erythromycin, azithromycin, or ciprofloxacin (differ according to local guidelines)

• Clostridium difficile : Oral metronidazole or vancomycin

• Helicobacter pylori : Amoxicillin+Clarithromycin 

• Acute bacterial otitis media : Amoxicillin 

• Upper respiratory infections (Pharyngitis/Laryngitis/Tonsillitis) : Phenoxymethylpenicillin 

• Cellulitis : Flucloxacillin

• Mastitis : Flucloxacillin

• Diabetic foot infection : Flucloxacillin

• Osteomyelitis/septic arthritis : Flucloxacillin with sodium fusidate

• Scabies : 5% permethrin

• Toxoplasmosis : Pyrimethamine+sulfadiazine.

Please see Q-4

Lichen planus is a skin disorder of unknown etiology, most probably being immune-mediated.

Features : 

• Purple, pruritic, papular, polygonal rash on flexor surfaces

• Lacy white pattern on buccal mucosa

Mnemonic: 4P - Purple Pruritic Papular Polygonal rash.

The shortness of breath, wheeze, and cough is probably due to asthma. Eczema fits the symptoms perfectly as atopic eczema has a family history and also is associated with asthma.

The signs and symptoms here point towards systemic lupus erythematosus (SLE).

The 3 best initial tests to order are anti-dsDNA titer, complement (C3 and C4), and ESR.

ESR may be raised but CRP may be normal unless there is intercurrent infection or serositis.

Polymorphic eruption of pregnancy (PEP) also known as pruritic urticarial papules and plaques of pregnancy (PUPPP) is a skin disorder in women during pregnancy characterized by an itchy urticaria-like rash, raised lumps, and inflamed areas of the skin that begins on the abdomen. It has a classic feature of sparing the umbilicus.

It usually happens in the woman’s first pregnancy around the third trimester. Pemphigoid gestations are itchy rashes that develop into blisters. It is occasionally mistaken for polymorphic eruption of pregnancy as both may look similar during the early form. Obstetric cholestasis does not present with a rash.

This is a clear episode of acute urticaria. In this question, her eyelids, lips, and tongue appear normal but remember that in acute urticaria, they can be either normal or associated with swelling (angioedema). Antihistamines especially non-sedating ones would be the treatment of choice. The preference for non-pregnant women would always be non-sedating and long-acting such as cetirizine or loratadine.

If in extreme cases, intravenous chlorpheniramine 10 mg would be given. In life-threatening swelling of the larynx or tongue, then administer adrenaline intramuscularly (adult dose: 0.5 ml of 1:1000).

Hydralazine can cause drug-induced lupus in which anti-histone antibodies are found in 95% of cases. Drug-induced lupus In drug-induced lupus, not all the typical features of systemic lupus erythematosus are seen, with renal and nervous system involvement being unusual. It usually resolves on stopping the drug.

Features :

• Arthralgia

• Myalgia, fatigue

• Skin (e.g. malar rash) and pulmonary involvement (e.g. pleurisy) are common

• Anti-histone antibodies are found in 95% of cases. While these symptoms are similar to those of systemic lupus erythematosus, they are generally not as severe unless they are ignored which leads to more harsh symptoms.

Symptoms of drug-induced lupus erythematosus generally disappear days to weeks after medication use is discontinued.

• The bluish discoloration most probably represents a Mongolian blue spot. They are also known as dermal melanosis.
• They are a type of benign, pigmented, flat, congenital birthmarks, which arise when the melanocytes are trapped deep within the skin. They are typically found around areas at the base of the back and on the buttocks.
• They usually fade after a few years and thus just reassurance would suffice.

Please see Q-18

This is a classic description of erythema multiforme which in this stem could have occurred secondary to strep throat or starting penicillin. It usually begins at the dorsum of hands and feet and then spreads. The term target shaped lesion here is a giveaway.

Please see Q-6

The findings are consistent with eczema. Having atopic disease in a first-degree relative favours the diagnosis of eczema.

The question here is quite straightforward. Itching without signs or symptoms of anaphylaxis. Manage with oral antihistamines.

Antinuclear antibodies (ANA) have the highest sensitivity meaning it is the most likely to be positive in patients with systemic lupus erythematosus.

However, ANA is not given in the options.

Anti-dsDNA would be next in line as it has a sensitivity of around 70%.

The 3 best initial tests to order for our lupus are usually anti-dsDNA titer, complement (C3 and C4), and ESR.

The signs and symptoms here point towards systemic lupus erythematosus (SLE). The 3 best initial tests to order are anti-ds DNA titre, complement (C3 and C4) and ESR. Given in the options are autoantibodies which include anti-dsDNA titres.

The stem here describes erythema multiforme which could be secondary to penicillin use or to the streptococci that is causing tonsillitis. Steven Johnson syndrome is considered the far end of the spectrum of erythema multiforme where there is extensive mucosal membrane involvement. This is not seen in this stem.

The fact that she has an itchy, scaly patch on her scalp are classic presentation of scalp psoriasis. Her aunt’s presentations with a similar rash on extensor aspects of her elbow and knees are suggestive of psoriasis.

Remember that Parkland formula is calculated from the time of the burn rather than the time of presentation.

PARKLAND FORMULA :

We use the Parkland formula to count the fluids required after burns. This is calculated from the time of the burn rather than the time of presentation.

If the presentation is delayed, fluid may need to be given more rapidly

Fluid requirements = Body area burned (%) x Weight (kg) x 4 mL.

Give 1/2 of total requirements in 1st 8 hours, then give 2nd half over next 16 hours. The area of body burn is calculated by adding the percentage of burns in each area using Wallace’s rule of 9’s.

• Head and neck total for front and back: 9%

• Each upper limb total for front and back: 9%

• Thorax and abdomen front: 18%

• Thorax and abdomen back: 18%

• Perineum: 1% 

* Each lower limb total for front and back: 18%

Please see Q- 4

This girl is suffering from urticaria. Oral antihistamines would be indicated. Since this is an allergic reaction, the only two reasonable options are B and C in this question. However, in the context of allergic reactions, IM adrenaline should only be used in an anaphylactic shock whereby the patient would have breathing difficulties.

The following are the indications of adrenaline in anaphylaxis:

1. Hoarseness of voice

2. Wheeze

3. Shortness of breath

4. Shock

5. Stridor

An urticaria-like allergic reaction, with none of the following indications stated above for adrenaline, then pick the oral antihistamine as the answer.

Scabies outbreaks in nursing homes and cases of crusted scabies may require combination therapy consisting of topical application of permethrin and 2 oral doses of ivermectin at 200 mcg/kg (administered 1 week apart).

Genital Herpes may be asymptomatic or may remain dormant for months or even years. When symptoms occur soon after a person is infected, they tend to be severe. They may start as multiple small blisters that eventually break open and produce raw, painful sores that scab and heal over within a few weeks. The blisters and sores may be accompanied by flu-like symptoms with fever and swollen lymph nodes.

There are three major drugs commonly used to treat genital herpes symptoms: acyclovir, famciclovir, and valacyclovir. These are all taken in pill form. Severe cases may be treated with the IV drug acyclovir.

SSCs Arise in squamous cells.

SCCs may occur on all areas of the body including the mucous membranes and genitals, but are most common in areas frequently exposed to the sun, such as the rim of the ear, lower lip, face, balding scalp, neck, hands, arms and legs. SCCs often look like scaly red patches, open sores, elevated growths with a central depression, or warts; they may crust or bleed.

A tissue sample (biopsy) will be examined under a microscope to arrive at a diagnosis. Squamous cell carcinomas detected at an early stage and removed promptly are almost always curable and cause minimal damage.

HSV

Common drugs causing erythema multiforme are: antibiotics (including, sulphonamides, penicillin), anticonvulsants (phenytoin, barbiturates), aspirin, antituberculoids, and allopurinol.

Erythema nodosum :

MOST COMMON CAUSES-

i) streptococcal infection

ii) sarcoidosis.

Other causes- tuberculosis, mycoplasma pneumonia, infectious mononucleosis, drugs- sulfa related drug, OCP, oestrogen; Behcet’s disease, CD, UC; lymphoma, leukemia and some others.

Itchy, scaly patches on the scalp are suggestive of scalp psoriasis. Her aunt's presentations (similar rash on extensor aspects of her elbow and knees) are also suggestive of psoriasis. It is thought to be an immunological disease.

The intensely itchy rash, scratch marks, and burrows on the wrist and elbow red papules on the penis are suggestive of scabies. Topical permethrin is used to treat it.

This is a case of scabies and scaly rash denotes the infection of the most severe type the crusted or Norwegian scabies. Should be treated with permethrine.

The probable diagnosis is scabies in which there is itching due to an allergic reaction to mites (Sarcoptesscabii) waste products.

Scabies is a skin infestation caused by a mite known as the Sarcoptesscabiei. Untreated, these microscopic mites can live on your skin for months. They reproduce on the surface of your skin and then burrow into it and lay eggs. This causes an itchy, red rash to form on the skin.

A pearly white umbilicated ulcer (with central depression) anywhere in the face with rolled edges / inverted edges is basal cell carcinoma. Any ulcer which is located above the neck is always basal cell carcinoma until proven otherwise. 

White lacy pattern of lesion is characteristic of lichen planus.

Any ulcer which is located above the neck is always basal cell carcinoma until proven otherwise.

Any ulcer which is located above the neck is always basal cell carcinoma until proven otherwise.

If a lesion is suspected to be infected should be given antibiotics. But if no response next step is to add an antifungal.

CD4 count 35 is too low indicating immunodeficiency where molluscum contagiosum occurs more easily. Umbilicated papules are a feature of molluscum contagiosum.

Chlamydial cervicitis

“Lacy white pattern” is used as a diagnostic description of lichen planus.

 It causes itchiness in the skin even where there is no obvious lesion to be seen.

It is most commonly associated with warts or verruca vulgaris often caused by HPV (human papillomavirus).

Acne Rosacea is characterized by recurrent episodes of facial flushing with persistent erythema, telangiectasia, papules, and pustules.

It is a chronic acneform disorder of the facial pilosebaceous glands with an increased reactivity of capillaries to heat, causing flushing and eventually telangiectasia.

Rhinophyma is an enlarged nose associated with rosacea which occurs almost exclusively in men.

Characteristic nail changes include pitting, discolouration, subungual hyperkeratosis, crumbling of the nail plate, and onycholysis.