Call me a hypochondriac, but when an unusual pea-sized lump appeared on my neck recently, it weighed on my mind so much I went to the doctor.

He told me it was most likely a “sebaceous cyst” – but referred me for an ultrasound just in case. Typically, the thing had completely disappeared by the time of the scan, so I felt like a time-waster, but I was still relieved (and mildly embarrassed) when the scanner couldn’t find anything.

While I was very lucky, unfortunately not all lumps behave in quite the same way – and some can be deadly, while others, like boils, can be incredibly painful.

We asked GP Dr Martin Godfrey to talk us through some of the more common lumps and bumps found on the body.

[Read more: Breast cancer – how to spot the signs and symptoms] 

How do lumps form and where do they most often appear?

Dr Godfrey explains: “There are lots of different ways of having lumps: you’ve got the skin surface and within the skin, you’ve got glands, like sweat glands, and then below that, you’ve got blood vessels and nerves, so any of those things can potentially create a lump.

“Often you’ll notice them most on the head and neck. The neck has a lot of lymph glands (or nodes), which contain white blood cells to fight infection. These swell when you’re infected, so you spot them particularly in children, who get lots of sore throats. You won’t see them very easily – you’ll more likely feel them.”

Should I be worried if my glands are swollen?

“Lymph nodes tend to hang around a while after an infection, so people do get concerned, but they’ll usually just resolve themselves. Your tonsils are also lymph nodes and if they keep on getting infected, they become chronically enlarged, and sometimes people eventually have them taken out.

“Dangerous sorts of swollen lymph nodes are seen more in older people – these are large, rubbery lymph nodes, which can be grape-sized. The worry with those is lymphoma, which can be a fatal blood condition.

“If you’re older and you haven’t had any infections, it’s worthwhile checking those out. And it’s worthwhile checking other places where lymph nodes hang out: underneath your armpit and in your groin.”

What else could lumps be?

Thyroid glands

“In the neck, your thyroid gland can get very big, particularly if you’re living in an area where there’s not enough iodine, which helps makes your thyroid hormones. In the past, you used to get goitres in people living in areas of low iodine. Enlarged thyroid glands can potentially indicate cancer as well.”

Sebaceous cysts

“These are particularly common on the scalp and forehead, and they are blocked sweat glands. They tend to be quite circular with a little hole in the middle, which is where the sweat gland itself is.

"The sweat gland just keeps on producing the sweat, but because it can’t get out, it expands and expands. It’s a very simple thing to get rid of surgically – it’s just full of what looks like toothpaste in a sack. They can get big sometimes and if they’re on your scalp, they get in the way of combing your hair.”

Infections

“Lumps and bumps can be caused by infections: so things like boils, which are painful, red and hot.”

Ganglion cysts

“These lumps are associated with your muscles and joints. You might have a little lump on your hand, your wrist or your ankles, called a ganglion, which is a cyst in the tendon itself. They’re a little bit sore and can be quite big, but are not dangerous. The old treatment for those used to be to hit them with the family bible and basically burst them, but that’s not recommended now!”

Lipoma

“The other common sort of lump you can have anywhere in your body is a lipoma, which is a benign, fatty swelling. They don’t move around under the skin, they can get very big and they can ultimately sometimes change from being benign into what’s called a liposarcoma, which is very dangerous.

"There isn’t a hard and fast rule – many doctors will say leave it – but if you are younger and have one, it’s probably best to have it removed. But if there’s a nerve nearby, there might be a numb area left.”

[Read more: Sherrie Hewson breaks down on Loose Women over breast lump issue]

Neurofibromas

“These tend to be benign, but there are some diseases where you get a lot of them and it can be something more serious. For instance, Joseph Merrick, the ‘Elephant Man’, had something called neurofibromatosis type 1 and as he got older, his lumps became quite uncontrollable.

The majority of these lumps are benign but people tend to ask if they can be sorted. Sometimes it can be difficult to tell for certain whether a lump is malignant or benign unless it’s biopsied.”

When should we go to the doctor?

“If there’s any lump which seems to be getting bigger quite quickly. Generally, if it’s an acute infection, then you’d know about it, they do swell up very quickly and they’re red. If it’s not red and hot and infected and it seems to be getting bigger over weeks, rather than days, then go to your GP and let them have a look at it.

“If you’ve got a lump that’s painful and starts to bleed, or if you notice any significant change in a short space of time, then it’s worth getting it checked out.”

If you have a lump you’re concerned about, check with your GP.