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November 14, 2013 / molehunter

Dermoscope not required

In the continuing quest to catch skin cancers of all kinds as early as possible, vigilance and an understanding of the natural history of the tumours that interest us are more important than dermoscopy.

This patient was seen at routine follow up for a different lesion. When he walked into the office, the physician immediately noticed something on the back of his hand which would most likely have been noticed had it been present 3 months earlier when he was last seen. The patient admitted it was new and growing.

squamous cell cancer

Nothing cryptic about this, its a New, Firm Growing (NFG) lesion. A new, growing solid nodule on the back of an older white man’s sun damaged hand is a squamous cell cancer until proved otherwise. Note the small but definite central keratin. No dermoscopy, no debate, straight to excision.

learning points 1) squamous cell cancers (SCCs) have a predilection for sun damaged sites especially the back of the hands, front of the lower leg in females and top of the bald scalp in men. They are occasionally seen in younger patients (Youngest I saw was age 40) but are VERY much more common over the age of 70, depending on skin type and outdoor exposure. The UK records about 35,000 cases a year.

SCC is nearly always cured by surgery, but depending on location and histological subtype (well, moderately or poorly  differentiated) they can invade deeply and may spread to other parts of the body, causing some 500 deaths per annum in Britain. They grow MUCH faster than basal cell cancers (BCCs). The dermoscope is of little use for these tumours except in a negative sense, i.e. ruling out basal cell cancers. BCCs have many positive features on dermoscopy as shown in several case studies here but the SCC’s features are all in the clinical presentation.

2) Always remember, SCCs are more common in immune suppressed patients (e.g. kidney transplant patients on ciclosporin/azathioprine) and may be very aggressive. Refer urgently.

3) Finally, yes its is just possible that this could be a harmless keratoacanthoma, but there is now a generally agreed consensus in the skin cancer world that you cannot make that judgment call clinically, it may be difficult even with histopathology. The keratoacanthoma mimics SCCs and is considered to be non malignant or possible a self-destructing SCC. Sometimes these lesions are listed for surgery but fall off spontaneously while waiting. I have seen this happen twice. But as I once heard a German professor say in this context ‘If it looks like a crow, sounds like a crow, hangs out with crows, it gets shot like a crow.’ Quite so.

PS-DO NOT attempt to treat lesions presenting like this with cryotherapy, as I did once or twice many years ago before I knew better. It hurts but it doesn’t work and only causes avoidable delay.

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