Dermatology

Question 1

Dermatofibroma

Answer 1

Dermatofibromas, also called histiocytomas, are firm, well defined, indolent, single or multiple nodules usually found over the extremities. They are freely mobile over the underlying tissues. Mild trauma or insect bite may trigger this tissue reaction.

Question 2

Lupus vulgaris

Answer 2

Lupus vulgaris (tuberculosis of the skin) usually occurs between 10-25 years of age. They appear as single or multiple cutaneous nodules commonly over the face. The ulcers tend to heal in one area as they extend to another. The mucous membrane of the mouth and nose are sometimes affected, either primarily, or as an extension from the face. Infection of the nasal cavity may lead to the necrosis of the underlying cartilage.

Question 3

Sebacious cyst

Answer 3

Sebaceous cysts are intradermal lesions containing keratin and its breakdown products. It is surrounded by a wall of stratified squamous keratinising epithelium. They commonly occur over the face, chest and shoulders. They have a characteristic punctum, usually in the centre of the lesion, which blocks the sebaceous outflow.

Question 4

Seborrhoeic keratoses

Answer 4

Seborrhoeic keratoses (basal cell papilloma) are benign tumours caused by the overgrowth of epidermal keratinocytes. It commonly occurs after the age of 40 years. They are frequently pigmented and often develop in large numbers in the sun exposed areas (the trunk, face and arms). It often appears greasy and its surface is characterised by a network of crypts.

Question 5

Nail changes

Answer 5

Nail changes are quite common in association with systemic diseases.

Beau’s lines are horizontal ridges in the nail indicating retardation of nail growth at the growth plate. This may occur in association with severe illness and a similar situation occurs with the hair. Consequently the hair is brittle at this point and hair loss occurs.

Kolonychia, or spoon shaped nails are typical of iron deficiency anaemia - low MCV, low Hb. It can also occur in association with trauma and the nail patella syndrome.

Ulcerative colitis like Crohn’s disease and cirrhosis is a gastrointestinal cause of clubbing.

Question 6

Dercums disease

Answer 6

This gentleman has multiple lipomas and the fact his brother has similar swellings makes a diagnosis of Dercum’s disease most likely.

A dermatofibroma is a benign neoplasm of the fibroblasts of the dermis, and as such, would be attached to the skin.

Campbell de Morgan spots are very common capillary naevi.

Osler-Weber-Rendu syndrome is a dominantly inherited genetic condition in which there are haemangiomata scattered over the mucous membranes which can cause gastrointestinal bleeding.

von Recklinghausen’s disease is an autosomal dominant condition defined as multiple congenital familial neurofibromatosis associated with

Fibroepithelial skin tags
Café-au-lait patches
Neuromata
Phaeochromocytoma.

Question 7

Marjolins ulcer

Answer 7

Marjolin’s ulcer is the name given to malignant change in a longstanding scar, ulcer or sinus.

Bowen’s disease is pre-malignant intradermal carcinoma usually associated with sun exposure.

Curling’s ulcer is peptic ulceration associated with severe burns.

Cushing’s ulcer is peptic ulceration associated with head injury.

Rodent ulcer is another name given to basal cell carcinoma.

Question 8

An 84-year-old lady presents to clinic with a lesion adjacent to her nose. On examination the lesion is pale, 1.5 cm in diameter and has a rolled pearly edge with a necrotic centre.

Answer 8

The description of this lesion is typical of a basal cell carcinoma.

Squamous cell lesions typically have raised everted rather than rolled pearly edges.

Malignant melanomas are usually pigmented and do not usually have rolled, pearly edges.

Cock’s peculiar tumour is ulceration and proliferation of a trichilemmal cyst.

Pyogenic granulomas are rapidly growing haemangiomas and are usually red.

Question 9

A 50-year-old builder attends clinic with a suspicious pigmented skin lesion that you suspect to be a malignant melanoma. The lesion does not appear to be significantly raised above the skin surface.
Which type of melanoma is it most likely to be?

Answer 9

Superficial spreading melanoma is the most common type of melanoma and represents approximately 65% of cases seen in the United Kingdom.

A nodular variety would be raised above the skin surface and account for 25%.

Lentigo maligna is seen in the elderly (10%) and acral lentiginous melanomas arise on the palms/soles or around the toenails.

Question 10

A 25-year-old female presents with concerns regarding the unsightly appearance of her toe nails.
They have a whitish discolouration extending up the nail bed in a number of the toes of both feet. They are entirely painless and she is otherwise well.
What is the most appropriate treatment?

Answer 10

Oral terbinafine

This young woman has typical features of fungal nail infection (onychomycosis) and the most appropriate treatment is oral antifungals as topical antifungals may be effective for one or two nails but not where there are a number affected.

Question 11

Stratum corneum

Answer 11

The stratum corneum is the last layer and provides a mechanical barrier to the skin therefore determines the mechanical functions of the skin. The hands and feet have thick stratum corneum as compared to the lips and eyelids. The thicker the stratum corneum is the more protection there is for the skin.

The dermis also has some factor to play with its elastic fibres and fibrous tissue.

The rest of the layers are also important but the mechanical properties are primarily determined by the stratum corneum.

Question 12

Diabetic foot

Answer 12

Callous formation at pressure areas is an important predictor of potential ulceration.

Plantar ulceration is usually a consequence of neuropathy and minor skin trauma is probably the most common initiating event.

Blood flow is often decreased with autonomic neuropathy hence sympathectomy may be performed to improve skin blood flow.

It is difficult radiographically to distinguish between Charcot’s joint and osteomyelitis.

Question 13

Necrobiosis lipoidica diabeticorum (NLD)

Answer 13

Necrobiosis lipoidica diabeticorum (NLD) is a painless rash with a central yellowish lipid-like core surrounded by a brownish/purplish periphery.

The condition is found in both type 1 and type 2 diabetes.

Ulceration of the lesion may occur.

NLD may be treated with PUVA therapy and improved therapeutic control.

Question 14

A 45-year-old teacher presents six weeks after he returns from a hiking holiday in South America with a shallow, painless ulcer of the nose.
What is the likely diagnosis?

Answer 14

Leishmaniasis

Given the history, the likely diagnosis is cutaneous leishmaniasis. Lesion pain and pruritus may be present in cutaneous leishmaniasis, but is not typical.

Diagnosis is by histologic section with staining for amastigotes.

Leishmania braziliensis is the likely pathogen which is spread by sandfly bites in endemic areas.

Fusobacterium causes the tropical ulcer which is an intensely painful, shallow ulcer.

Question 15

A 52-year-old obese lady with lipodermatosclerosis and eczema over both calves presents to her GP with a large ulcer over the medial malleolus of her left ankle. ABPI: 1.05.

Answer 15

Venous ulcer
Venous ulcers usually lie proximal to the medial or lateral malleolus, though they may extend to the ankle or dorsum of the foot. They are frequently secondary to venous incompetence as a result of varicose veins or deep venous thrombosis. Lipodermatosclerosis sometimes accompanies venous ulcers.

Question 16

A 38-year-old known alcoholic presents with paraesthesia in his feet associated with ulceration over the distal tips of three toes on the left foot and the dorsal aspect of the right ankle. ABPIs are: 0.98 (right); 0.96 (left).

Answer 16

Neuropathic ulcers can result from peripheral sensory neuropathy secondary to alcohol abuse. These ulcers are due to altered sensory neuropathy (diabetic neuritis, spina bifida, tabes dorsalis, leprosy).

Neuropathic ulcers usually develop at the sites of trauma (pressure) such as toes and heels. ABPIs in diabetic patients may be falsely high due to the rigid vessel walls. Therefore, in diabetic patients it is important to assess peripheral sensory neuropathy which may be a cause for the ulceration.

Question 17

A 44-year-old lady with known inflammatory bowel disease presents with a large ulcerating lesion over the anterior shin of the right leg which has a blue overhanging necrotic edge. Her ABPIs are normal.

Answer 17

Pyoderma gangrenosum are recurring nodulo-pustular ulcers with a tender red/ blue overhanging necrotic edge, commonly affecting the legs, abdomen and face. It is associated with:

inflammatory bowel disease
acute leukaemia
polycythaemia rubra vera
autoimmune hepatitis
Wegener's granulomatosis, and
myeloma.

Question 18

A 26-year-old Jamaican lady presents with a four month history of a painful ulcer over the anterior shin of the right leg. ABPIs are normal. She is anaemic and has mild splenomegaly.

Answer 18

Sickle cell disease is hereditary haemolytic anaemia occurring mainly among those of African (Afro-Caribbean) origin. The haemoglobin ‘S’ molecule crystallises during reduced blood oxygen tension causing vascular occlusion. Depending on the affected vessel, patients may have bone or joint pain, priapism, neurological abnormalities, skin ulcers.

Question 19

A 72-year-old lady with known ischaemic heart disease and diabetes mellitus presents with a deep ulcer over the lateral malleolus of her right leg. Sensations are normal over both the lower limbs. ABPIs are: 0.48 (right); 0.65 (left).

Answer 19

Arterial ulcers are usually secondary to peripheral vascular disease.

Question 20

A 27-year-old woman presents with a palpable, raised, and sharply delineated black patch over the lateral aspect of her leg. She says that it itches and bleeds occasionally.

Answer 20

Nodular melanoma
Nodular melanoma is the most malignant type. These may occur over any part of the body. These are palpable, deeply pigmented, and usually convex in shape; they may bleed or ulcerate. It is sharply delineated from the surrounding skin. It has a poor prognosis with early lymphatic involvement.

Question 21

A 72-year-old woman presents with a brown pigmented patch over her cheek which has an irregular outline. On examination, there is thickening and development of a discrete tumour nodule.

Answer 21

Lentigo maligna melanoma
Lentigo maligna (Hutchinson's melanotic freckle) is the least malignant variety (carcinoma in situ). It is more commonly seen in the elderly. It presents as an irregular brown patch commonly over the cheek. Malignant changes are recognised by thickening,darkening and the development of discrete tumour nodule(s). This indicates dermal invasion by malignant melanocytes and the lesion is then a lentigo maligna melanoma.

Amelanotic melanoma is non-pigmented and acral-lentiginous melanoma is common in the extremities, palm and sole. Acral lentiginous melanoma is mostly seen in Japanese and in dark skinned races. As in nodular melanomas, their prognosis is poor.

Question 22

A 69-year-old farmer presents with a three month history of a solitary, fleshy, and elevated nodule over his right cheek. It has a central hyperkeratotic core.

Answer 22

Keratoacanthoma is the ‘self-healing’ squamous cell carcinoma. It is seen mostly on sun-exposed sites. It is usually solitary but may be multiple. It presents as a fleshy, elevated and nodular lesion with a central hyperkeratotic core.

The most significant histologic feature is its rapid growth. The short history and rapid increase in size suggest keratoacanthoma rather than squamous cell carcinoma.

Question 23

Squamous cell cancer

Answer 23

The most commen dermatological malignancy is a basal cell carcinoma, with squamous being the next most common. But it is cutaneous squamous cell carcinoma (SCC) that is most common in immunocompromised transplant subjects.

Squamous carcinomas can also occur in the lung, cervix and oesophagus.

SCCs metastasise to regional lymph nodes and characteristically has an everted edge.

DOES NOT:
Metastases to bone most frequently
Occurs more frequently than basal cell carcinoma
Only occurs on sun exposed skin
Typically has rolled edges

Question 24

Malignant melanoma

Answer 24

Amelanotic type is more aggressive than the pigmented type

Malignant melanoma may be subungual, buccal, anal, and present on any mucosal surface, not merely in the dermis/epidermis.

The incidence of malignant melanoma of the skin has been rising rapidly in the white populations around the world for several decades. Incidence rates in Great Britain increased from around 2 per 100,000 population for males and 3 per 100,000 population for females in 1971 to 7 and 9 per 100,000 population for men and women respectively in 1996, a threefold increase.

Amelanotic malignant melanoma most commonly occurs in the setting of melanoma metastasis to the skin, presumably because of the inability of these poorly differentiated cancer cells to synthesise melanin pigment.

More than 50% of cases are believed to arise de novo without a pre-existing pigmented lesion.

Tumour size is only one of the criteria used in the AJCC 2009 Revised Melanoma Staging. Tumour thickness and mitotic rate (mitoses/mm2) are the most important prognostic factors in the primary tumour.

Question 25

Dermoid cyst

Answer 25

Rupture is associated with foreign body type inflammation

Dermoid cysts are solitary, or occasionally multiple, hamartomatous tumours.

The tumour is covered by a thick dermis-like wall that contains multiple sebaceous glands and almost all skin adnexa.

Hairs and large amounts of fatty masses cover poorly to fully differentiated structures derived from the ectoderm.

Depending on the location of the lesion, dermoid cysts may contain substances such as nails, hair, horny masses and dental, cartilage-like and bone-like structures.

Cutaneous cysts most commonly occur on the head (forehead), mainly laterally around the eyes. Occasionally, they occur on the neck or in a midline region.

Question 26

Keratocanthoma

Answer 26

Also called molluscum sebaceum

Central necrosis with ulceration is a common feature.

It is not of infective origin, indeed it may be difficult to differentiate from squamous cell carcinoma under the microscope.

Keratoacanthoma usually remits spontaneously, but often leaves a scar.

Question 27

Keloid scars

Answer 27

> Afro caribbeans
Keloid scars are characterised by smooth hard nodules caused by excessive collagen production. Keloid scarring is much commoner in people of Afro-Caribbean origin. They also tend to affect young adults a lot more.

Keloid scarring may occur spontaneously but is associated with skin trauma, infection, and surgery.

There is no evidence to suggest that keloid scarring is associated with steroid therapy. However, if keloid scarring is treated with surgical removal then it must be followed by steroid injection or superficial radiotherapy or it may make the problem worse.

There is no evidence to suggest that keloid scarring is associated with wound healing by secondary intention. There is some evidence to suggest that primary wound closure is a risk factor.

Local anaesthetics are not associated with keloid scarring. They can be used in surgical removal of the scar.

Other methods of treatment include triamcinolone injection and compression with silica gels.

Question 28

Malignant melanoma II

Answer 28

May develop in a pre-existing benign naevus

As with all skin cancers, malignant melanoma is associated with exposure to UV light and the sex incidence is roughly equal.

Features of malignant change within a pre-existing naevus include

Change in size
Change in colour
Ulceration
Crusting
Itching
Bleeding and
The appearance of satellite lesions.
It is more common with fair skin, in red heads and people of Celtic origin.

Men often present with lesions affecting the trunk and women with lesions affecting the legs.

Malignant melanoma accounts for almost all skin cancer deaths.

Question 29

Cutaneous markers of systemic, non-haematological malignancy

Answer 29

Acanthosis nigricans is a pigmented rough thickening of the skin (velvety thickened and pigmented skin) in the axillae or groin with associated warty lesions. It could be a marker of underlying adenocarcinoma of the stomach.

Acquired ichthyosis is generalised dry skin and may suggest a underlying carcinoma.

Dermatomyositis is a purplish rash often affecting the eyelids and the face, associated with muscle weakness. Lung cancer in both sexes, and breast and genital tract cancer in females should be excluded.

Erythema multiforme can be divided into a minor and a major form.

Minor form (target lesions usually found on the extensor surfaces, especially of peripheries) is caused by herpes simplex, Mycoplasma and other viruses.
Major form (Stevens-Johnson syndrome) is caused by reaction to sulphonamides and penicillins, and is associated with systemic upset, fever and severe mucosal involvement.
Erythema multiforme is sometimes associated with lymphoma and leukaemias.

Thrombophlebitis migrans are successive crops of tender nodules affecting blood vessels throughout the body seen in approximately 10% of patients with carcinoma of the pancreas (especially body and tail tumours).

Question 30

Melanoma prognosis

Answer 30

The thinner the lesion the greater the chances of survival.

Incidence is increasing rapidly.

Treatment of malignant melanoma depends upon staging.

Unfavourable sites include the scalp, hands, feet, and mucous membranes.

Males and older patients have a poorer prognosis.

Question 31

Hypertrophic scarring

Answer 31

Usually occurs across flexor surfaces

Over healing leads to hypertrophic or keloid scarring.

Hypertrophic scars classically

Develop soon after surgery
Subside with time
Are limited by the boundary of the wound
Occur with motion (compression)
Usually occur across flexor surfaces and
Improve with appropriate surgery.

Question 32

Keloid scars II

Answer 32

Keloids are dermo-proliferative disorders unique to humans and of unknown aetiology. They are thought to have a familial tendency and are seen 5-15 times more frequently in non-whites.

Hypertrophic scars are confined to the borders of the original wound, but keloids extend beyond the original scar margins.

Whilst anatomical locations such as genitalia, eyelids, palms and soles are usually spared, keloids are more common in wounds that cross tension lines and in areas such as the earlobe, presternal and deltoid regions.

Hypertrophic scars generally begin to develop in the weeks after injury, whereas keloids can develop up to one year later.

Various treatment modalities including surgical excision have been tried, but no treatment, at present, seems to be curative for keloids. Intralesional steroid therapy and pressure therapy are useful to keep the lesion under control.

Question 33

Cutaneous squamous cell carcinomas

Answer 33

Management dependent on patient and age

A margin of 10 mms is usually recommended for cutaneous squamous cell carcinomas (SCC).

However, if such margins cannot be achieved due to anatomical constraints (such as tumours around the eyes), surgery plus adjuvant treatment such as radiation should be considered. Radiation therapy can be effectively employed in patients over 55 years of age, particularly around the eyelids, nose, and lip.

A recurrent lesion is usually treated by complete excision and grafting rather than a skin flap since the adjacent tissue (that is, the flap) could have tumour cells.

Elective lymph node dissection is not performed routinely.

Five per cent to 10% of SCC metastasise.

Lesions on the scalp that arise in areas of previous radiation are particularly prone to metastasis.

Question 34

Sebaceous cysts II

Answer 34

Commonly occur on the scalp

Sebaceous cysts are discernible by their

Central punctum
Dermal topography
Fluctuance within the dermis and their
Contents of sebaceous materials.
Sebaceous cysts may become acutely infected with ensuing local inflammation.

Question 35

Pyoderma gangrenosum

Answer 35

Is characterised by bluish haemorrhagic cribriform edges

Pyoderma gangrenosum are multiple skin abscesses with necrosis and undermining ulcerations commonly affecting the legs, abdomen and face.

The basic lesion is a necrotising cutaneous vasculitis with rapidly developing haemorrhagic liquefying tissue necrosis of the skin.

No specific organism or combination of organisms has been identified with this disease entity although frequently Proteus and other Gram negative organisms and beta-haemolytic Streptococci have been cultured from these wounds.

It is characterised by ulceration surrounded by bluish haemorrhagic cribriform edges.

It is associated with

Ulcerative colitis (50% of cases)
Diverticulosis
Regional enteritis
Peptic ulcer disease
Carcinoid tumour
Rheumatoid arthritis
Acute leukaemia
Polycythaemia rubra vera
Autoimmune hepatitis
Wegner's granulomatosis and
Myeloma.
However, no systemic disease is evident in 20% of cases.

The course of pyoderma gangrenosum is often protracted and in some instances fulminant.

Question 36

Seborrhoeic keratoses

Answer 36

May be associated with internal malignancy

Seborrhoeic keratoses (basal cell papilloma, seborrhoeic wart) is a common lesion often seen in large numbers on the trunk, face, and arms of middle-aged and older individuals.

They are benign tumours caused by the overgrowth of epidermal keratinocytes. They are frequently pigmented and often develop as single or multiple, round or oval shaped slightly greasy lesions with a ‘stuck on’ appearance.

Sometimes they occur in crops in sun-exposed areas and are often characterised by a network of crypts.

Multiple seborrhoeic keratosis may be associated with an internal malignancy (Leser-Trelat sign).

Treatment options include shave excision curettage, superficial electrodessication and freezing with liquid nitrogen.

Question 37

Uncommon feature of dermoid cysts?

Answer 37

If found in the orbital region is usually located in the medial angle of the eye

Dermoid cysts are solitary, or occasionally multiple, hamartomatous tumours.

The tumour is covered by a thick dermis-like wall that contains multiple sebaceous glands and almost all skin adnexa. Hairs and large amounts of fatty masses cover poorly to fully differentiated structures derived from the ectoderm.

Depending on the location of the lesion dermoid cysts may contain substances such as nails, hair, horny masses and dental, cartilage-like, and bone-like structures.

Cutaneous cysts most commonly occur on the head (forehead), mainly laterally around the eyes. Occasionally, they occur on the neck or in a midline region.

Question 38

Erythroderma

Answer 38

Erythroderma is associated with Sézary syndrome and mycosis fungoides.

Erythema nodosum is associated with sarcoidosis.

Pyoderma gangrenosum is associated with inflammatory bowel diseae (c 50%) rheumatoid arthritsis and (rarely) with haematological malignancy where it may be the first indication of the disease.

Splinter haemorrhages are associated with subacute bacterial endocarditis (SBE).