AIDD Course Back up website: Module 13 A Benign Skin Tumours

Chapter 20 Benign Skin Tumours

There are many benign skin tumours but the ones you need to be able to recognise are Seborrhoiec keratoses, Solar keratoses, Sebaceous or epidermoid cysts, Warts, Pyogenic granuloma, Dermal nevi, Sebaceous hyperplasia, Xanthelasma, Trichoepithelioma, Dermatofibroma, Syringoma, Pilomatrixoma, Keloid scars, Molluscum contagiosum and Juvenile xanthogranuloma.

There is a podcast on this module that you can listen to either before you do the reading of the module or after, whichever you prefer! Podcast on Benign skin tumours. Just click on the little arrow next to the loudspeaker motif on the left side of the bar to start the podcast.

You should then view this video discussing the images in this part of the module.

As the skin ages it unfortunately developes a variety of benign skin tumours. The commonest and the most troublesome are seborrhoeic keratoses. There is a strong genetic element to these lesions. They are particularly prominent under the breasts and on the back in obese individuals and they tend to come on maximally after the age of 50, but occasionally you will get a younger individual with a lot. When they are small they can be frozen off with liquid nitrogen so that you do not leave a white mark. They can be burned off with lasers or can be shaved with a number 14 blade. Seborrhoeic keratoses can take a variety of forms some of which are really quite flat initially and look like melanomas, but they do not have the normal pigment pattern that you would see with a melanocytic lesion under the dermatoscope. Sometimes a seborrhoeic keratosis will become irritated ,usually when the body is developing an immune reaction to it, or when it has been traumatised. These lesions can look surprisingly like squamous cell skin cancers and you may only be able to make the diagnosis after tissue has been removed and submitted for pathology.

Habif has some excellent pictures on page 784 thru 792 of the various stages of development of a seborrhoeic keratosis and the structures that may be seen within it. It is worthwhile looking at these just to get a feel for the lesions. He also goes into lesions that may almost mimic melanomas but just shows what the picture looks like under the dermatoscope.

Dermnet on Seborrhoeic keratoses

Skin tags are also quite common usually again in obese individuals but around the neck and in the flexures particularly in the axillae and under the breasts. These lesions when small may be frozen off, but you usually have to put a bit of local anaesthetic under them and just snip them off and cauterise the surface. Excess skin tags are common in obese individuals and pre diabetics with high insulin levels and insulin resistance.

Dermnet on Skin tags

Skin tag like pedunculated nevi

Seborrhoeic keratosis and the dermatoscopic view

Typical stuck on seborrhoeic keratoses.

The sign of Leser-Trelat is an eruptive seborrhoeic keratoses appearing in someone with an internal malignancy. I would have to admit that this is not a diagnosis that I make. There are usually numerous patients who just have multiple keratoses, but I suppose it is the sudden onset of these that may make you think of a person having an internal malignancy. It is thought that a tumour producing humeral factor for example, transforming growth factor alpha, could be responsible for the acute eruption of these lesions.

Dermnet on the sign of Leser Trelat

Stucco keratoses are again genetically inherited and commonly seen around the ankles. These lesions can be easily picked off in the bath and are also just a variant of seborrhoeic keratosis.

Dermnet on Stucco keratoses

Habif goes on to describe dermatosis papulosa nigra usually seen in dark skinned individuals, particularly Negroes.

Dermnet on Dermatosis papulosa nigra

Cutaneous horns. With a cutaneous horn it is always important to feel the base that is indurated and consider that there may be a squamous cell skin cancer there. It is worth either shaving these or excising these lesions and submitting them for pathology.

Dermatosis papulosa nigra

Stucco keratoses are seen around the ankles

Multiple eruptive seborrhoeic keratoses

Dermatofibromas are really very common lesions particularly in women and usually on the thighs or upper arms. The lesions characteristically involute when you are putting lateral pressure on them. They may have a surrounding halo of pigmentation just due to irritation of the overlying melanocytes. Dermatoscopy usually shows a white lacy centre. They are benign and should just be left.

Dermnet on Dermatofibromas

Dermnet on Clear cell acanthoma

The dimpling sign when lateral pressure is applied to a dermatofibroma

A larger more exophytic dermatofibroma

These lesions often also have a collarette of scales

Hypertrophic scars and keloids are a big problem after surgery but may occur spontaneously in some individuals with a genetic predisposition and particularly if they develop acne lesions on the chest wall. Keloids are more common in Negroes. On page 788 Habif goes into various ways of treating them. My experience of intralesional steroid with either 10mg per ml of Kenacort or subsequently 40mg per ml usually with a bit of local anaesthetic, is a useful treatment given a month apart. Cryotherapy can be used to soften the keloids so that the injection is easier. Silicone gel sheeting can be applied for two to four months at least 12 hours a day to try to flatten the scar.

Dermnet on keloids and hypertrophic scars

Latest work on difficult keloid scars. From a Colleague- I remember someone mentioning combining injectable 5-FU with intralesional steroid for keloids. It was thought to be more efficacious. I think the dose used is 50 mg per ml, but the only vials of 5-FU that I can find are single use and contain 1000mg in 20 ml. If anyone has experience in this treatment would they be kind enough to confirm the dose, and where they obtain 5-FU from?

Yes we used smaller ampoules- DBL FU INJECTION is mentioned in MIMS 500 mg/10 mls-looks as as though its freely available (MIMS 2013 NO 4)

The new trick is to use an ablative Fx laser on low density- punch a few holes then rub the injectable in vigorously-- apparently the thing keloids hate most is damage to overlying epidermis so any puncturing has to be low density.

Rox Anderson and others were saying at AAD last weekend that both 5FU and triamcinolone gave results as good or better as with infiltration in layers. The fractionated laser will improve matters alone but the drug into the holes has added benefit.

Keloid on the ear. They commonly occur on the ear lobe after ear piercing.

Some patients unfortunately keloid badly after surgery.

Keratoacanthomas are rapidly evolving variants of squamous cell skin cancer that do not metastasise and are usually seen in sun exposed areas. They can uncommonly occur after what is thought to be a solar keratosis is frozen with liquid nitrogen. Some of the lesions will involute within a period of three to four months but it is generally better to excise or curette these lesions when they are small because you never know how big they will get. Often pathologists will report them as well differentiated squamous cell skin cancers. Habif deals with the treatment of these lesions and the various options on page 797. This can include excision, curette and cautery, Imiquimod topically, intralesional Methotrexate and even radiotherapy depending on the clinical circumstances.

Dermnet on keratoacanthomas

Epidermal nevi are seen at birth or they may thicken up at puberty depending on hormonal stimulation of some of the structures that make them up. A curious type of epidermal nevus is an ILVEN or inflammatory linear verrucous epidermal nevus. These lesions occur along the lines of Blaschko and once evolved will tend to persist.

It is generally best to wait until puberty before excising these lesions, or if they cannot be excised a CO2 laser can be used to flatten them although to try to remove them completely you usually have to go deep enough to cause scarring. Occasionally epidermal nevi can be associated with internal problems particularly skeletal, ocular and central nervous system disorders and patients who have extensive epidermal nevi should always be examined by a paediatrician for these pathologies.

A keratoacanthoma on the forehead with a typical keratin core.

A giant keratoacanthoma on the shoulder

Dermnet on Epidermal nevi

A nevus sebaceous is a particular type of epidermal nevus that is seen in the scalp. It has a lot more sebaceous elements to it and its claim to fame is that basal cell skin cancers can develop in these as can other benign adnexal tumours usually after puberty. In general surgical excision sometime after puberty is recommended. If tumours are going to occur it is usually in adults over 40 years of age.

Dermnet on Nevus sebaceous

Sebaceous nevus on the forehead. These lesions are often yellowish.

Congenital melanocytic nevus on the arm.

Small epidermal nevi like this are of no significance and can be easily shaved off and the base lasered.

Habif goes on to describe the condition of chondrodermatitis nodularis chronica helicis which is really a pressure necrosis of cartilage, particularly on the most protuberant part of the ears, which may be the helix or in some people the conchae, depending on the anatomy of the ear. These areas usually have to be excised with a little wedge excision if they are causing the patient to waken from sleep at night. Usually they are mistaken for squamous cell skin cancer.

Dermnet on Chondrodermatitis nodularis helicis

These are usually on the most protuberant part of the cartilaginous ear and interfere with sleep. They may be mistaken for an scc.

It can be difficult to distinguish these from SCCs without a biopsy

Epidermal cysts or sebaceous cysts generally occur on the face, back, scalp or ears. Similar lesions may be seen on the scrotal skin. Generally these lesions slowly evolve over the years and provided they do not rupture they cause very little trouble. Once they do rupture the cyst wall becomes adherent and it is difficult to remove them. Pilar cysts occur on the scalp and are really much the same as epidermal sebaceous cysts but it produces a different type of keratin from the epidermal cyst.

Dermnet on various cysts

Dermnet on Pilomatrixoma

Sebaceous cyst with a blocked central punctum.

This hard lesion on a childs cheek is a pilomatrixoma, a calcified follicular benign tumour

Sebaceous hyperplasia on the forehead is a common benign tumour of sebaceous glands. They seem to have a small central dell and can look both like basal cell skin cancers and even molluscum contagiosum. Nonetheless the yellowish material around the edges of the punctum is very suggestive of sebaceous hyperplasia. These lesions can be left or can be frozen. Habif has some good pictures of them on page 807.

Sebaceous adenomas are larger sebaceous tumours on the face and lack the dell of sebaceous hyperplasia. They may be a marker for the Muir Torre syndrome which is associated with uterus ovary and bowel carcinomas. A greater association of this syndrome is a sebaceous carcinoma. These lesions typically occur around the eyelids and periocular skin.

Dermnet on the Muir- Torre syndrome

Dermnet on Sebaceous hyperplasia

Syringomas are benign sweat gland tumours particularly seen on the lower eyelid. They may fluctuate in size particularly in hot summer months when people sweat excessively, almost disappearing in the winter. They can be removed either by gently excising them with scissors or doing punch excisions. Occasionally a whole group can be excised with primary closure.

Dermnet on syringomas

Sebaceous hyperplasia

Benign sweat gland tumours around the eyelids are known as syringomas.

Trichoepitheliomas are firm pale or skin coloured tumours on the face around the nose and nasolabial folds

Benign Skin Lesions that look like Malignancy Keep this for Reference later

Flat pigmented Seb ks, Sebaceous hyperplasia, Pilomatricomas, Sebaceous nevi scalp

Pigmented lesions- Talon noir, Dark hemangiomas, Reed nevi,Blue nevi and cellular blue nevi, Melanoacanthoma,

Ulcers Pyoderma gangrenosum, Mycobacterium ulcerans, Trigeminal trophic syndrome,

Infections Some warts, Cutaneous TB, Leishmaniasis, Atypical mycobacteria, Sporotrichosis, Bacillary angiomatosis

Other Lumps Chondrodermatitis nodularis helicis, Scabetic nodules, Pyogenic granulomas, some Dermatofibromas, Juvenile xanthogranuloma, Lymphocytoma, Granuloma faciale. Lymphomatoid papulosis, Trichoepitheliomas, Clear cell acanthomas, Angiolymphoid hyperplasia with eosinophilia.

Additional Image Resources

Dermnet on Xanthomas

Dermnet on Pilomatrixoma

Dermnet on Juvenile xanthogranulomas

Primary Care Dermatology Society UK