A swelling may be visible on inspection or not be detected until palpation is carried out. The lump may be discrete and localized or be diffuse, when it is more properly designated a swelling. The important features of swellings that provide diagnostic information are site, anatomical plane, relationship to structures, temperature, tenderness, consistency, mobility, fluctuation, pulsatility, state of regional lymph nodes. In addition, specific lumps have additional characteristics that can be demonstrated by appropriate clinical tests.
Position, location, shape and size of swellings
The first feature that should be noted is the position of the lump and its relationship to adjacent anatomical structures, the plane of location (subcutaneous, intramuscular, intra-abdominal). A lump that is superficial to a muscular compartment, e.g. situated in the subcutaneous plane, is rendered more prominent when the patient is made to contract the relevant muscles. By contrast, this manoeuvre makes a lump become less distinct on both inspection and palpation if the lesion lies within or beneath a muscular compartment. In subcutaneous swellings, it is often possible to ‘pinch’ the skin over the summit of the lesion. This cannot be achieved with intra- cutaneous lumps such as sebaceous cysts. During this stage of the examination, a note is also made of the shape and size (in two diameters) of the lump. Size is important in planning surgical excision and in the assessment of the effect of non-surgical therapy for inflammatory and neoplastic lesions.
Palpation of a lump should be carried out gently and, initially, the temperature of the lesion, the presence of any tenderness noted. Surface discoloration (erythema, bruising, etc.) should also be noted.
An inflammatory swelling will be tender, hot, erythematous, indurated and oedematous. It is important to note, however, that some rapidly growing malignant neoplasms may exhibit an inflammatory appearance virtually indistinguishable from that caused by infective conditions. This is encountered most commonly in the breast, where differentiation between a breast abscess and inflammatory cancer may be difficult.
The mobility of a lump is tested in two planes at right angles to each other. For lumps situated over a muscle compartment, contraction of the muscle group is important before mobility is assessed since a lesion may be infiltrating the muscles and still appear to be mobile if the muscle is not contracted. Mobility does not designate a lump as benign. Indeed, many benign lumps exhibit limited mobility because of attachment of anatomical structures (e.g. ganglion, because of its attachment to tendons and joint capsule; goitre, because the thyroid is tethered to the trachea). The majority of neoplastic lesions are mobile in the early stages and become fixed only when they infiltrate surrounding tissues.
Consistency, dullness and resonance
The feel or consistency of a lump is probably its most important clinical feature. It may be solid and hard (when the possibility of neoplasia arises), tense, soft, cystic, or pulsatile (vascular origin). Most enlarged lymph nodes feel rubbery. Solid and fluid-containing lumps are dull on percussion. Some swellings contain gas or gas-filled viscera, in which case they are resonant.
A superficial fluid-containing cavity or collection is fluctuant. Fluctuation is very useful for the detection of non-inflamed localized collections of fluid and blood. Generally speaking, cystic lumps and swellings are soft, although a tense cyst may feel hard. The benign tumour of fat (lipoma), which often presents as a subcutaneous lump, also fluctuates on testing.
A fluid thrill may be present in some cystic swellings. This may be elicited by tapping one side of the swelling and detecting the transmitted percussion wave with the examining fingers placed on the opposite side of the swelling.
Transillumination involves shining a light through a swelling to detect whether it transmits light brilliantly or not. Transillumination is a function of the optical density of the component elements of the swelling. Thus a cyst containing clear fluid (e.g. hydrocele, cystic hygroma) transilluminates brilliantly, one containing opalescent fluid (spermatocele) less so. Fat (lipoma) and subcutaneous tissues also transilluminate to a varying extent.
Examination of vascular swellings
A swelling arising from an artery is usually the result of localized dilatation (aneurysm) and demonstrates expansile pulsation. The most common example encountered in clinical practice is abdominal aortic aneurysm, which must be palpated gently because of the risk of rupture. In superficial aneurysms, a vascular thrill caused by the turbulent flow in the aneurysm is felt on palpation. Some non-vascular (solid or cystic) lesions apposed to large arteries transmit arterial pulsations. The differentiation between expansile and transmitted pulsations is important and requires bidigital palpation, with each index finger placed on either side of the swelling. If the lump is intrinsically pulsatile, the index fingers are separated with each systolic impulse.
Dilated (varicose) veins are obvious on inspection, especially with the patient standing up. When the proximal part of the long saphenous vein is dilated (due to incompetence at the saphenofemoral junction), it forms a uniform bulge in the immediate subinguinal region and is known as a saphena varix. This swelling also exhibits a fluid thrill that is elicited by tapping the vein below the swelling and feeling the impulse with the fingers of the other hand placed over the varix.
Examination of hernial swellings
The characteristic features of hernial swellings (inguinal, paraumbilical and incisional) are increased prominence with a rise in intra-abdominal pressure (cough, contraction of abdominal musculature, erect posture) and an impulse, visible and palpable, when the patient coughs. There is one important exception to these observations: a femoral hernia usually presents as a subinguinal lump that does not have a cough impulse and does not change in size with change in posture.