Dermatology for MRCP Part 1

A 30-year-old man has well-demarcated red plaques with silvery scale over both elbows, knees and his scalp. His fingernails show pitting and separation of the nail from the bed. The plaques are only mildly itchy. What is the most likely diagnosis?

1. Lichen planus Purple, flat-topped, itchy bumps. That does not match well-defined silvery-scaled patches on the elbows and knees with nail pitting.
2. Cutaneous T-cell lymphoma Patches that will not go away and can look like eczema or psoriasis. Here, well-defined silvery-scaled patches on the elbows and knees with nail pitting points elsewhere.
3. Seborrhoeic dermatitis Greasy scale in the oily areas of the skin. It does not fit well-defined silvery-scaled patches on the elbows and knees with nail pitting.
4. Eczema Itchy inflammation with a less clear edge, mainly in the skin folds. But well-defined silvery-scaled patches on the elbows and knees with nail pitting does not point to it.
5. Psoriasis correct Correct. Well-defined silvery-scaled patches on the elbows and knees with nail pitting is chronic plaque psoriasis.

The point: Psoriasis is a common, long-term skin disease caused by the immune system, driven by a type of immune cell called a T-cell switching on and skin cells (keratinocytes) being made and shed too fast. The commonest type, chronic plaque psoriasis, causes well-defined red patches (plaques) with silvery scale over the elbows, knees, scalp and behind the ears, with nail changes such as pitting and the nail lifting away from the bed (onycholysis). Other patterns are guttate psoriasis (small drop-like spots after a strep throat infection), flexural (inverse) psoriasis in the skin folds, pustular psoriasis, and the rare emergency of erythrodermic psoriasis, where almost the whole skin is affected. Up to a third of patients develop psoriatic arthritis, so joints should be checked, and there is a link with metabolic syndrome (a cluster of conditions including high blood pressure and high blood sugar) and heart disease risk. Triggers include strep infection, stress, injury to the skin (the Koebner phenomenon, where new patches appear along a scratch or scar), and drugs such as beta-blockers, lithium and antimalarials, with a flare-up if steroid tablets are stopped suddenly. First-choice treatment of plaque disease is a cream or ointment: a strong steroid cream plus a vitamin D cream such as calcipotriol. When creams are not enough, light treatment (phototherapy) and then drugs that work throughout the body (methotrexate, ciclosporin, acitretin) or biologic drugs are used under a specialist. It is a lifelong condition that flares up and settles down, managed to control it rather than cure it, with attention to the joint and heart risks that go with it.

Source: NICE CG153 — psoriasis: assessment and management NICE · tier 1, national regulator or guidance

A 30-year-old man has well-demarcated red plaques with silvery scale over both elbows, knees and his scalp. His fingernails show pitting and separation of the nail from the bed. The plaques are only mildly itchy. What is the most appropriate investigation?

1. Skin biopsy only if the diagnosis is unclear For cases that do not look typical. Here, well-defined silvery-scaled patches on the elbows and knees with nail pitting points elsewhere.
2. Clinical diagnosis from the appearance and distribution correct Correct. Psoriasis is diagnosed just by how it looks and where it is.
3. Screen for psoriatic arthritis Because it is common. That does not match well-defined silvery-scaled patches on the elbows and knees with nail pitting.
4. Throat swab in guttate psoriasis For a strep throat trigger. But well-defined silvery-scaled patches on the elbows and knees with nail pitting does not point to it.
5. Assess cardiovascular and metabolic risk Because of the link with these conditions. It does not fit well-defined silvery-scaled patches on the elbows and knees with nail pitting.

The point: Psoriasis is a common, long-term skin disease caused by the immune system, driven by a type of immune cell called a T-cell switching on and skin cells (keratinocytes) being made and shed too fast. The commonest type, chronic plaque psoriasis, causes well-defined red patches (plaques) with silvery scale over the elbows, knees, scalp and behind the ears, with nail changes such as pitting and the nail lifting away from the bed (onycholysis). Other patterns are guttate psoriasis (small drop-like spots after a strep throat infection), flexural (inverse) psoriasis in the skin folds, pustular psoriasis, and the rare emergency of erythrodermic psoriasis, where almost the whole skin is affected. Up to a third of patients develop psoriatic arthritis, so joints should be checked, and there is a link with metabolic syndrome (a cluster of conditions including high blood pressure and high blood sugar) and heart disease risk. Triggers include strep infection, stress, injury to the skin (the Koebner phenomenon, where new patches appear along a scratch or scar), and drugs such as beta-blockers, lithium and antimalarials, with a flare-up if steroid tablets are stopped suddenly. First-choice treatment of plaque disease is a cream or ointment: a strong steroid cream plus a vitamin D cream such as calcipotriol. When creams are not enough, light treatment (phototherapy) and then drugs that work throughout the body (methotrexate, ciclosporin, acitretin) or biologic drugs are used under a specialist. It is a lifelong condition that flares up and settles down, managed to control it rather than cure it, with attention to the joint and heart risks that go with it.

Source: NICE CG153 — psoriasis: assessment and management NICE · tier 1, national regulator or guidance

A 30-year-old man has well-demarcated red plaques with silvery scale over both elbows, knees and his scalp. His fingernails show pitting and separation of the nail from the bed. The plaques are only mildly itchy. What is the most appropriate management?

1. Avoid known triggers and manage cardiovascular risk Such as certain drugs and stress. But well-defined silvery-scaled patches on the elbows and knees with nail pitting does not point to it.
2. Emollients and scalp preparations For symptom control. Here, well-defined silvery-scaled patches on the elbows and knees with nail pitting points elsewhere.
3. Biologic therapy for severe disease When other treatments do not work. It does not fit well-defined silvery-scaled patches on the elbows and knees with nail pitting.
4. Potent topical corticosteroid with a vitamin D analogue correct Correct. First choice for plaque psoriasis is a strong steroid cream with a vitamin D cream.
5. Systemic agents such as methotrexate under specialist care For widespread or hard-to-treat disease. That does not match well-defined silvery-scaled patches on the elbows and knees with nail pitting.

The point: Psoriasis is a common, long-term skin disease caused by the immune system, driven by a type of immune cell called a T-cell switching on and skin cells (keratinocytes) being made and shed too fast. The commonest type, chronic plaque psoriasis, causes well-defined red patches (plaques) with silvery scale over the elbows, knees, scalp and behind the ears, with nail changes such as pitting and the nail lifting away from the bed (onycholysis). Other patterns are guttate psoriasis (small drop-like spots after a strep throat infection), flexural (inverse) psoriasis in the skin folds, pustular psoriasis, and the rare emergency of erythrodermic psoriasis, where almost the whole skin is affected. Up to a third of patients develop psoriatic arthritis, so joints should be checked, and there is a link with metabolic syndrome (a cluster of conditions including high blood pressure and high blood sugar) and heart disease risk. Triggers include strep infection, stress, injury to the skin (the Koebner phenomenon, where new patches appear along a scratch or scar), and drugs such as beta-blockers, lithium and antimalarials, with a flare-up if steroid tablets are stopped suddenly. First-choice treatment of plaque disease is a cream or ointment: a strong steroid cream plus a vitamin D cream such as calcipotriol. When creams are not enough, light treatment (phototherapy) and then drugs that work throughout the body (methotrexate, ciclosporin, acitretin) or biologic drugs are used under a specialist. It is a lifelong condition that flares up and settles down, managed to control it rather than cure it, with attention to the joint and heart risks that go with it.

Source: NICE CG153 — psoriasis: assessment and management NICE · tier 1, national regulator or guidance