Is my child's lump cancer? — reassurance and the red flags that actually matter

Reactive lymph nodes are almost always soft or slightly doughy when you press them — similar in consistency to a grape. A lump that feels hard like a marble, or rubbery and firm with a distinct edge, has a different tissue quality that clinicians take seriously. Hardness suggests that the lump is made of something more solid than an inflamed, fluid-filled node. That does not mean it is necessarily cancer — a firm cyst, a granuloma from a past infection, or scar tissue can all feel hard — but it does mean the lump needs examination rather than watchful waiting. Paired with the other features in this list, firmness is one of the features that guides a paediatrician to refer for imaging or a specialist opinion.

Reactive lymph nodes are usually tender when pressed — that mild soreness is a sign of inflammation, which means the immune system is working. A lump that is entirely painless is more unusual, because the absence of tenderness suggests it is not inflamed in the usual way. Equally important is the timeline: a node that appeared alongside a cold and still has not reduced in size three to four weeks after the cold resolved is not behaving like a normal reactive node. Nodes linked to infection should begin to shrink as the infection clears. Growth after the illness has gone — or growth that accelerates — is a signal that something other than a simple immune reaction may be happening. A doctor's examination at this point is appropriate, and an ultrasound scan of the lump is a quick, painless way to characterise it.

Location matters significantly when evaluating a lump in a child. Lymph nodes in the neck, under the jaw, and in the armpit or groin are very commonly reactive and almost always benign. The supraclavicular region — directly above the collarbone — is different. Nodes in this location are much less commonly reactive from superficial infections because the lymph vessels draining into those nodes come from deeper structures: the chest, the mediastinum (the space between the lungs), and the abdominal organs. A lump in the supraclavicular region in a child without an obvious cause for it is considered a red flag in paediatric clinical guidelines across multiple countries, including guidance from the British Society for Paediatric and Adolescent Haematology. It warrants prompt specialist referral rather than watchful waiting.

A benign lymph node sits relatively freely in the surrounding tissue — when you gently press it with your fingertip, it slides a little, similar to a small ball bearing under the skin. When a lump feels as though it is stuck to deeper structures — or when the overlying skin seems attached and does not move separately from the lump — it is described as "fixed." Fixation happens when a mass grows into or involves surrounding tissue, which can happen in both inflammatory conditions and in cancer. This feature alone is not diagnostic, but in combination with painlessness, firmness, or prolonged persistence, a fixed lump is a clear reason to seek medical evaluation within days. Your doctor will assess mobility as part of the routine clinical examination.

It is not unusual for a child to have two or three swollen neck nodes after a throat infection — all draining the same infection source. What is more unusual is for multiple lymph node groups in separate, unconnected regions of the body to enlarge simultaneously. For example: nodes in both the neck and the groin, or nodes in the armpit alongside an enlarged spleen felt as fullness in the upper left abdomen. This pattern of generalised lymph node enlargement (called generalised lymphadenopathy) can occur in some viral illnesses — infectious mononucleosis ("glandular fever") is one common example — but it also occurs in lymphoma and leukemia. If your child has noticeable swelling in multiple sites at the same time, a doctor's assessment that includes a blood count is appropriate promptly.

Systemic symptoms — symptoms that affect the whole body rather than one localised area — are the most important red flags to know when asking "when should I worry about child symptoms." A lump that is accompanied by fever lasting more than two weeks without a clear cause, noticeable weight loss over several weeks, or drenching night sweats that soak pyjamas and bedding is no longer just a lump. These three together — fever, night sweats, weight loss — are what oncologists call "B symptoms," recognised as associated with lymphoma and some other cancers. Even two of these three, appearing together with a persistent lump, should prompt a doctor's appointment within days. Add unusual pallor, easy unexplained bruising, or bone pain to any of these, and contact a specialist without delay.