A bump is a small raised area of the skin caused by an abnormal tissue on the skin surface or within the skin. Common causes of small red bumps at the back of the neck are insect bites, ingrown hair and bacterial folliculitis. Epidermoid cysts and shingles are more rare. Larger red bumps include boils and skin cancer.
A lump is an abnormal mass of tissue under the skin, which can appear normal or reddish. Soft lumps at the back of the neck include infected swollen lymph nodes, lipomas, buffalo humps and congenital abnormalities, such as angiomas. Hard lumps include muscle knots, bone spurs and cancerous lymph nodes.
A. Small Red Bumps or Rashes (<1 cm)
A.1. Bacterial Folliculitis
A.2. Ingrown Hair
Ingrown hair (razor bumps) usually appears as a group of small (1-3 mm) red or dark brown bumps and hair loops–hair exiting and re-entering the skin. Ingrown hair mostly occurs on a recently shaved skin in black people and others with curly hair. Treatment includes avoiding shaving and antibiotic, steroid and tretinoin ointments.
A.3. Lice Bites
Lice bites can cause multiple flat red itchy bumps at the back of the neck. One or more small (~1 mm) white lice are usually tightly attached to the hair (but dandruff, which can look similar, is not).
Mosquito or other insect bites can, in sensitive people, cause similar red bumps.
Shingles (Herpes zoster) appears as a group of translucent, itchy and burning vesicles surrounded by reddened skin on either side (right or left) of the back of the neck and shoulder. Shingles is caused by reactivation of a latent Varicella-zoster virus in the roots of the spinal nerves. Treatment is with antiviral ointments or oral drugs, such as acyclovir.
Picture 3. Shingles (Herpes zoster) at the back of the neck (source: Samuel Freire da Silva, MD, Atlasdermatologico)
A.5. Other Rashes at the Back of the Neck
Red rashes at the back of the neck that appear in the form of scaly patches rather than bumps include fungal infections (ringworm), seborrheic dermatitis, allergic or irritant contact dermatitis (eczema) and psoriasis.
B. Large Red Bumps (>1 cm)
B.1. Boil (Furuncle, Carbuncle)
A boil appears as a red tender bump with a white center or opening. Smaller boils (furuncles) are pea-sized and larger ones (carbuncles) can be cherry-sized or bigger. Some boils can spontaneously drain pus. A boil is caused by an infection of one or more hair follicles, usually by the bacterium Staphylococcus aureus or, sometimes, with methicillin-resistant Staphylococcus aureus (MRSA) . Treatment includes topical antibiotics (fusidic acid, mupirocin), oral antibiotics (flucloxacillin) or an incision with drainage .
B.2. Epidermoid Cyst
Epidermoid cyst is an overgrowth of the cells from the uppermost skin layer (epidermis) in the deeper skin layer (dermis). A cyst, which develops slowly, usually does not cause any symptoms, but when inflamed, it can have a fleshy appearance and can be tender or painful . A cyst may have an opening that oozes a greasy material. The size of the cyst can range from few millimeters to few centimeters. Risk factors include genetic predisposition, trauma and surgery. Treatment is by surgical removal . A cyst very rarely develops into cancer .
Epidermoid cysts are often wrongly referred to as sebaceous cysts. True sebaceous cysts, which develop from the sebaceous glands, are rare.
Keloid is a scar-like overgrowth of tissue in the skin that develops slowly as a reaction to an ingrown hair, injury or surgical wound. It occurs in genetically predisposed individuals, mainly in dark-skinned people. Some keloids can partially heal on their own. Treatment can include emollients, steroid injections, surgical removal or a topical chemotherapeutic mitomycin-C [8,9].
Picture 6. Keloids – raised fleshy plaques (source: Samuel Freire da Silva, MD, Atlasdermatologico)
B.4. Skin Cancer
Basal cell carcinoma is a type of skin cancer that appears as a raised plaque or nodule on sun-exposed areas, mainly on the face and back of the neck. It usually develops slowly in older individuals who have been commonly exposed to sunlight, for example, fishermen and farmers. The tumor can ulcerate and can be locally aggressive but rarely spreads to distant areas. Treatment can include various ointments, cryotherapy, radiotherapy and surgical excision .
Picture 7. Basal cell carcinoma as a large ulcerated plaque at the back of the neck (source: Samuel Freire da Silva, MD, Atlasdermatologico)
C. Soft Lumps
Lumps grow under the skin.
A direct hit to the back of the neck can cause a bruise – a soft, tender lump that changes color from red to purple, black, green and brown or yellow.
A whiplash injury, fall or other cause of strain of the neck muscles can cause soft tender lumps at the nape of the neck.
C.2. Swollen Lymph Nodes
The most common cause of swollen lymph nodes at the back of the neck are bacterial or fungal infections of the head and neck skin, systemic viral infections in children and seborrheic dermatitis. Soft lumps at the hairline (at the base of the skull) develop within several days after onset of infection; they are covered by normal or reddened skin and have well-defined borders. The lump, which can be painful or painless, have no openings in the skin.
Lipoma is a slow-growing benign tumor of fat tissue that grows under the skin. It usually appears as a soft lump with normal overlying skin that slips over the lump. Its size can range from few to more than 15 cm. Usually it does not cause any symptoms, but it can interfere with the neck movements. Treatment is by surgical removal.
C.4. Buffalo Hump
Buffalo hump is excessive fat in the form of a soft dome-shaped bulge at the nape of the neck. It can develop in Cushing’s syndrome or other conditions with increased release of the hormone cortisol and after prolonged treatment with steroids . The excessive fat can be surgically removed.
C.5. Congenital Abnormalities in Children
Cystic hygroma is a congenital abnormality in children; it appears as a large soft lump in the neck; it can exceed 10 cm .
D. Hard Lumps
Muscle knots appear as pea-sized rubbery nodules covered by normal skin. The causes include overuse of the muscles in the neck (trapezius, levator scapulae), bad posture and painful conditions in the neck, such as a herniated disc. The knots may not be visible, but can be palpable under the fingers.
D.2. Bone Spur (Osteophyte)
Bone spurs at the back of the neck appear near the vertical midline of the neck as small fixed, hard lumps. The lumps are usually not visible but can be palpable. They represent an overgrowth of the bony tissue of the spine. They can be caused by osteoarthritis (cervical spondylosis), rheumatoid arthritis or other type of arthritis or from an injury. Bone spurs by themselves do not cause any symptoms, but when they press upon the spinal nerves they can cause pain, tingling and numbness in the neck, shoulder or upper arm (cervical radiculopathy). Symptoms of arthritis include neck stiffness and swelling of the joints, manly in the hands. Bone spurs can be detected by an X-ray, but for a diagnosis of the underlying disorder a MRI is usually needed.
D.3. Cervical Kyphosis
Cervical kyphosis is an abnormal outward curvature of the neck spine with a hump at the nape of the neck . Common causes include:
- A congenital abnormality (present from birth)
- A dowager’s hump, which develops in some individuals with forward head posture (mainly in older women)
- Degenerative disc disease or spinal osteoarthritis
- A fracture of the upper thoracic or lower cervical vertebra due to osteoporosis or bone tumor (can occur without pain) or injury
An X-ray or MRI may be needed to get a diagnosis.
D.4. Cancerous Lymph Nodes
“Stone-hard” pea-sized and fixed lumps near the hairline can be cancerous lymph nodes. Such nodes usually result from a spread of cancer on the scalp or back of the neck. Lymph nodes affected by lymphoma usually have a rubbery consistence. Diagnosis can be made by a biopsy of the affected nodes.
D.5. Spinal Tumors and Pseudotumors
Tumors and pseudotumors in the cervical spine appear as hard lumps near the neck midline.
Bone tumors can arise from the vertebra or intervertebral discs or can spread to the spine from other organs .
A pseudotumor can be caused by tuberculosis of the cervical vertebra .
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