Posted in science

Why do we get ‘lumpy’ scars?

Having recently undergone some rather invasive surgery on my knee, I watched with fascination as my flesh and skin knitted itself back together at an impressive rate. However, as you all no doubt know, injuries unfortunately tend to leave some sort of mark. In my case, I have what looks rather like a lop-sided and slightly sceptical face on my left knee (depicted in a rather fetching puce). If you were to overcome your natural aversion and give the marks a prod, the flesh surrounding the scars is unnaturally hard and smooth. So, my question is – what is this mysterious lump, and why has it formed?

According to a quick peruse of the NHS website (link below), there are four main types of scar: flat and pale, the name also being the description; keloid, a raised and overgrown lump; hypertropic, raised and red; and atrophic, sunken or pitted. The most common of these is the ‘flat and pale’ scar, although it really does depend on the type of wound that has occurred – the further apart the edges of the wound, the more scar tissue will be formed. Now, although knowing the different names and types is well and good, what actually are scars?

Scars are, in general, made up of fibrous connective tissue, a type of tissue which contains a high percentage of a protein called collagen. Fibrous connective tissue (i.e. scar tissue) is really dense, and is therefore sometimes referred to as ‘dense connective tissue’. I know, medical people come up with really inventive names. Fibrous connective tissue is also found in uninjured tissue, but there is much less of it. In fact, although it is present in normal tissue, its structure in the two places is radically different. In normal tissue, the collagen forms a sort of ‘basket weave’ effect with all the strands criss-crossing and overlapping, whereas when a scar is formed the collagen proteins are all aligned in the same direction, giving the scar its shiny/smooth appearance and texture. The angry red colour of a new scar stems from the increased blood flow to the area after the initial injury and throughout the healing process. Over time, the blood flow decreases, causing the scar to gradually pale in colour, eventually turning a silvery grey (although the end colour does depend on individual pigmentation). Due to the normal skin having been replaced with this new tissue, scars don’t contain melanin, produce sweat or grow hair.

Now we know a bit more about the structure of scar tissue, it seems that the lumps beneath the scars on my knee are simply large masses of this fibrous connective tissue that have formed around the incision. Pretty cool, huh? Apparently this ‘lumping’ effect will either go away on its own or it won’t, although I’m sure that you can read more about that topic on a more specialised site.

So, to conclude: scars are formed from a collagen-rich type of tissue called ‘fibrous connective tissue’. This can collect beneath or around the site of a wound, causing hard lumps to form (which *maybe* go away on their own with time). So there you have it – a whistle-stop tour on scar formation, prompted by my very own mangled knee.

Tabitha Watson