Skin

Question 1

What is sebhorroeic keratosis?

Answer 1

Most commonly arise in patients over the age of 50 years, often idiopathic
Equal sex incidence and prevalence
Usually multiple lesions over face and trunk
Flat, raised, filiform and pedunculated subtypes are recognised
Variable colours and surface may have greasy scale overlying it
Treatment options consist of leaving alone or simple shave excision

Question 2

What is congenital melanocytic naevi?

Answer 2

Typically appear at, or soon after, birth
Usually greater than 1cm diameter
Increased risk of malignant transformation (increased risk greatest for large lesions)

Question 3

What is junctional melanocytic naevi?

Answer 3

Circular macules
May have heterogeneous colour even within same lesion
Most naevi of the palms, soles and mucous membranes are of this type

Question 4

What is compound naevi?

Answer 4

Domed pigmented nodules up to 1cm in diameter
Arise from junctional naevi, usually have uniform colour and are smooth

Question 5

What is spitz naevus?

Answer 5

Usually develop over a few months in children
May be pink or red in colour, most common on face and legs
May grow up to 1cm and growth can be rapid, this usually results in excision

Question 6

Describe epidermoid cysts

Answer 6

Common and affect face and trunk
They have a central punctum, they may contain small quantities of sebum
The cyst lining is either normal epidermis (epidermoid cyst) or outer root sheath of hair follicle (pilar cyst)

Question 7

Describe dermatofibroma

Answer 7

Solitary dermal nodules
Usually affect extremities of young adults
Lesions feel larger than they appear visually
Histologically they consist of proliferating fibroblasts merging with sparsely cellular dermal tissues

Question 8

Describe sebaceous cysts

Answer 8

Originate from sebaceous glands and contain sebum.
Location: anywhere but most common scalp, ears, back, face, and upper arm (not palms of the hands and soles of the feet).
They will typically contain a punctum.
Excision of the cyst wall needs to be complete to prevent recurrence.
A Cock’s ‘Peculiar’ Tumour is a suppurating and ulcerated sebaceous cyst. It may resemble a squamous cell carcinoma- hence its name.

Question 9

Describe BCC

Answer 9

Most common form of skin cancer.
Commonly occur on sun exposed sites apart from the ear.
Sub types include nodular, morphoeic, superficial and pigmented.
Typically slow growing with low metastatic potential.
Standard surgical excision, topical chemotherapy and radiotherapy are all successful.
As a minimum a diagnostic punch biopsy should be taken if treatment other than standard surgical excision is planned.

Question 10

Describe SCC

Answer 10

Again related to sun exposure.
May arise in pre - existing solar keratoses.
May metastasize if left.
Immunosupression (e.g. following transplant), increases risk.
Wide local excision is the treatment of choice and where a diagnostic excision biopsy has demonstrated SCC, repeat surgery to gain adequate margins may be required.

Question 11

Describe the treatment of suspicious skin lesions

Answer 11

Suspicious lesions should undergo excision biopsy. The lesion should be removed in completely as incision biopsy can make subsequent histopathological assessment difficult.
Once the diagnosis is confirmed the pathology report should be reviewed to determine whether further re-excision of margins is required (see below)

Question 12

Describe margins of excision required depending on breslow thickness

Answer 12

Lesions 0-1mm thick 1cm
Lesions 1-2mm thick 1- 2cm (Depending upon site and pathological features)
Lesions 2-4mm thick 2-3 cm (Depending upon site and pathological features)
Lesions >4 mm thick 3cm

Question 13

What is Kaposi sarcoma

Answer 13

Tumour of vascular and lymphatic endothelium.
Purple cutaneous nodules.
Associated with immuno supression.
Classical form affects elderly males and is slow growing.
Immunosupression form is much more aggressive and tends to affect those with HIV related disease.

Question 14

Describe dermatofibroma

Answer 14

Benign lesion.
Firm elevated nodules.
Usually history of trauma.
Lesion consists of histiocytes, blood vessels and fibrotic changes.

Question 15

Describe pyogenic granuloma

Answer 15

Overgrowth of blood vessels.
Red nodules.
Usually follow trauma.
May mimic amelanotic melanoma.

Question 16

Describe acanthosis nigricans

Answer 16

Brown to black, poorly defined, velvety hyperpigmentation of the skin.
Usually found in body folds such as the posterior and lateral folds of the neck, the axilla, groin, umbilicus, forehead, and other areas.
The most common cause of acanthosis nigricans is insulin resistance, which leads to increased circulating insulin levels. Insulin spillover into the skin results in its abnormal increase in growth (hyperplasia of the skin).
In the context of a malignant disease, acanthosis nigricans is a paraneoplastic syndrome and is then commonly referred to as acanthosis nigricans maligna. Involvement of mucous membranes is rare and suggests a coexisting malignant condition.

Question 17

Describe Actinic keratosis

Answer 17

Actinic keratosis is viewed as a premalignant lesion because there are atypical keratinocytes present in the epidermis. In a person with 7 actinic keratosis the risks of subsequent SCC is of the order of 10% at 10 years. The primary lesion is a rough erythematous papule with a white to yellow scale. Lesions are typically clustered at sites of chronic sun exposure.

Question 18

Describe SCC in situ

Answer 18

Also known as Bowens disease the commonest presentation of in situ SCC is with an erythematous scaling patch or elevated plaque arising on sun exposed skin in an elderly patient. Lesions may arise de novo or from pre-existing actinic keratosis.
Pathologically there is full thickness atypia of dermal keratinocytes over a broad zone. Nuclear pleomorphism, apoptosis and abnormal mitoses are all seen.

Question 19

Describe kerathocanthoma

Answer 19

Dome shaped erythematous lesions that develop over a period of days and grow rapidly. They often contain a central pit of keratin. They then begin to necrose and slough off. They are generally benign lesions although some do view them as precursors of malignancy. They may be treated by curettage and cautery. If there is diagnostic doubt (they can mimic malignancy) then formal excision biopsy is warranted.

Question 20

Describe pyogenic granuloma

Answer 20

These present as friable overgrowths of granulation at sites of minor trauma. They may be ulcerated and bleeding on contact is common. They may be treated with curretage and cautery, formal excision may be used if there is diagnostic doubt.

Question 21

What is a tru cut biopsy

Answer 21

Most often used for percutaneous sampling of deep seated lesions or used intra operatively for visceral lesions

Question 22

What is a 5mm punch biopsy

Answer 22

Used for diagnostic confirmation of lesions that are suspected to be benign or where the definitive management is unlikely to be surgical