Skin Lumps and Bumps (Lipoma, Sebaceous Cyst)

What are skin lumps and bumps?

Skin lumps and bumps are localised swellings or growths that arise beneath or on the surface of the skin. Many are benign conditions, such as lipomas and sebaceous (epidermoid) cysts, and often grow slowly over time. However, skin lumps may also represent malignant conditions, including basal cell carcinoma, squamous cell carcinoma, or melanoma. Because early skin cancers can sometimes resemble benign lesions, medical evaluation is important, particularly for lumps that are new, enlarging, painful, ulcerated or changing in appearance.

Lipomas

A lipoma is a benign tumour composed of mature fat cells (adipocytes). It presents as a soft, smooth, and usually painless lump under the skin that moves easily when pressed. Lipomas can develop anywhere on the body but are most often found on the trunk, shoulders, neck or upper arms. 

Sebaceous (epidermoid) cysts

Commonly referred to as “sebaceous cysts”, these are actually epidermoid cysts, encapsulated sacs filled with keratin rather than sebum. They appear as firm, round bumps under the skin and often have a small, dark central opening known as a punctum. Most are painless and move slightly when pressed. Sebaceous cysts can occur anywhere on the body but are most commonly seen on the face, neck, chest, back and occasionally in the genital area. When inflamed or infected, they may become red, swollen and tender, sometimes discharging thick, whitish material.

What do these skin lumps and bumps look like?

The appearance and feel of a skin lump can vary depending on whether it is a lipoma or a sebaceous (epidermoid) cyst. Although both are benign, recognising their typical features helps differentiate them from other conditions that may look similar.

Lipomas

Lipomas are soft, smooth lumps that lie just beneath the skin. They can be easily moved under light pressure and are generally painless. Most lipomas are located in the fatty layer (subcutaneous tissue) and grow slowly over time. Each lipoma is enclosed within a thin fibrous capsule, which prevents it from spreading to surrounding tissue. They are typically round or oval in shape and tend to appear symmetrical. While most remain small, some can grow larger than 10 centimetres in diameter—these are referred to as “giant lipomas.”

In rare situations, a lipoma may resemble a more serious growth such as a liposarcoma. Features such as rapid growth, pain, or firmness should be assessed by a healthcare provider to ensure an accurate diagnosis.

Sebaceous (epidermoid) cysts

These cysts appear as round, dome-shaped bumps beneath the skin, often with a visible dark punctum at the centre. They are typically firm but compressible and can range in size from a few millimetres to several centimetres. Sebaceous cysts are located in the subepidermal layer of the skin and may occasionally rupture, releasing their keratinous contents.

Ruptured cysts

When a cyst ruptures, it can cause inflammation of the surrounding tissue, leading to:

• Redness and swelling
• Tenderness and pain
• Yellow, thick, cheese-like discharge

In deeper ruptures, infection may occur when bacteria enter the cyst cavity, causing abscess formation. Such cases can sometimes be mistaken for skin abscesses or boils and should be examined by a doctor for proper treatment.

What causes skin lumps and bumps?

The causes of skin lumps such as lipomas and sebaceous (epidermoid) cysts differ, but both result from local changes within the skin or underlying tissue. While most cases occur without a clear reason, certain genetic, metabolic or environmental factors can increase the likelihood of developing them.

Lipoma

The exact cause of lipomas remains uncertain, but research suggests both genetic and acquired factors play a role.

• Genetic changes — around two-thirds of lipoma cases show mutations involving the HMGA2 gene, which influences cell growth and fat tissue formation.

• Inherited conditions — lipomas may occur more frequently in people with genetic disorders such as Gardner syndrome, multiple hereditary lipomatosis, adiposis dolorosa (Dercum’s disease) and Madelung’s disease. These conditions predispose individuals to multiple fatty growths.

• Trauma — minor injuries may trigger local inflammation and release growth factors that stimulate fat cell development at the affected site, a process known as post-traumatic lipoma formation.

• Metabolic and endocrine factors — people with obesity, diabetes or high cholesterol levels (hyperlipidaemia) have been observed to develop lipomas more often, although these associations are not fully understood.

Sebaceous (epidermoid) cyst

These cysts arise from the hair follicle’s infundibulum, where keratin and dead skin cells become trapped under the surface. While most occur spontaneously, several factors may contribute:

• Inherited conditions — syndromes such as Gardner syndrome, Gorlin syndrome and Favre–Racouchot syndrome are linked with early-onset or multiple cysts, often appearing before puberty.

• Skin trauma — injury or repeated irritation can cause skin cells to become embedded beneath the surface, forming a cyst.

• Chronic sun exposure — long-term ultraviolet damage may increase the risk of epidermoid cysts, particularly in older adults.

• Medications — certain drugs, including BRAF inhibitors (used in melanoma treatment), imiquimod (for viral warts), and cyclosporine (an immunosuppressant), have been associated with the formation of cysts, especially on the face and scalp.

Most lipomas and cysts are harmless, but understanding their potential causes helps identify when medical evaluation or preventive care may be appropriate.

Who is at risk of skin lumps and bumps in Singapore? 

While lipomas and sebaceous (epidermoid) cysts can develop in anyone, certain factors make some individuals more prone to these benign growths. Understanding these risks helps with early detection and timely treatment if needed.

• Age — while both lipomas and sebaceous cysts are most common in adults, lipomas tend to occur between 40 and 60 years old, whereas sebaceous cysts are more frequent between 20 and 60 years old. Lipomas are rare in children, while cysts may appear earlier, especially in individuals with a genetic predisposition..

• Genetic factors — a family history of lipomas or epidermoid cysts increases the likelihood of developing similar growths. Inherited syndromes such as Gardner syndrome, Gorlin syndrome and multiple hereditary lipomatosis are known to cause multiple lesions.

• Skin type and conditions — people with oily or acne-prone skin are more likely to develop sebaceous cysts, as their skin tends to produce excess keratin and sebum, leading to blocked hair follicles.

• Previous trauma or surgery — minor skin injuries, scars or repeated friction may trigger local tissue changes that result in cyst formation or post-traumatic lipomas.

• Metabolic and hormonal factors — individuals with obesity, diabetes or hyperlipidaemia have been observed to develop lipomas more frequently, possibly due to metabolic changes affecting fat cell growth.

• Medication use — long-term use of certain medications, such as BRAF inhibitors, cyclosporine or steroids can alter skin cell turnover and increase the risk of cyst formation.

Although most of these factors are not preventable, awareness and early evaluation of new or changing lumps help ensure proper management and peace of mind.

How are skin lumps and bumps diagnosed?

Most lipomas and sebaceous (epidermoid) cysts are diagnosed based on their appearance and feel during a clinical examination. However, additional tests may be performed to confirm the diagnosis, assess deeper or unusual lumps, and rule out rare but serious conditions such as liposarcoma or other soft tissue tumours.

• Physical examination — diagnosis usually begins with a thorough examination of the lump and a review of your medical and family history. Your doctor will assess the lump’s size, consistency, mobility and tenderness, as well as its location and rate of growth. Soft, movable, painless lumps are typical of lipomas, while firm, dome-shaped lesions with a central punctum suggest a sebaceous cyst. Your doctor may also ask about previous skin injuries, infections or medications that could contribute to lump formation.

• Imaging tests — imaging is used when the diagnosis is uncertain, when a lump is unusually large or deep, or when it is close to vital structures such as nerves or blood vessels. These scans help determine the exact nature, size, and depth of the lesion.

• Ultrasound — a quick, non-invasive test that distinguishes solid from cystic lumps and defines the structure of lipomas or cysts. It is the first-line imaging method because it is safe, accessible, and cost-effective.

• Magnetic Resonance Imaging (MRI) — MRI provides detailed images of soft tissues and is useful for evaluating deep or atypical lipomas, especially when malignancy needs to be ruled out.

• Computed Tomography (CT) — CT scans are occasionally used to assess deep or complex lesions, particularly in areas not easily visualised by ultrasound or MRI. In some cases, imaging may also be part of pre-operative planning, especially for large lesions that may be compressing nearby nerves, blood vessels, or joints.

• Biopsy and histological testing — a tissue sample may be taken if the lump has suspicious features, grows rapidly or does not fit the typical appearance of a lipoma or cyst. More commonly, the tissue is sent for histological confirmation after surgical removal to ensure the diagnosis is benign.

In most patients, no extensive investigations are needed. However, medical evaluation remains important to confirm the diagnosis, rule out rare malignancies and plan appropriate treatment.

What are the treatment options for skin lumps and bumps in Singapore?

Most lipomas and sebaceous (epidermoid) cysts are harmless and do not require treatment unless they cause pain, discomfort, infection, or cosmetic concern. Your doctor may recommend removal if the lump becomes large, interferes with daily activity or shows changes in appearance or texture.

Lipoma

Lipomas are best treated through surgical removal when necessary.

• Surgical excision — this is the most effective treatment for lipomas. The procedure involves making a small incision over the lump, carefully removing the fatty tissue along with its capsule, and closing the wound with sutures. Removing the capsule is essential to prevent recurrence. Lipoma excision is typically performed under local anaesthesia for small lesions, while larger or deeper ones may require sedation or general anaesthesia. Early removal is recommended when the lipoma is small, as larger lipomas can press on nearby structures such as nerves, joints or blood vessels, making surgery more complex and recovery slower.

Sebaceous (epidermoid) cyst

Treatment depends on whether the cyst is infected, inflamed, or purely cosmetic: 

• Incision and drainage — used when a cyst becomes acutely infected and forms an abscess. The doctor makes a small incision to release the pus and relieve pain. Once the inflammation subsides, definitive removal of the cyst wall is performed later to prevent recurrence.

• Surgical excision — this is the definitive treatment. The doctor makes an elliptical incision over the cyst and removes both the contents and the capsule. Complete removal of the capsule prevents the cyst from returning. For larger cysts, a small amount of overlying skin may also be removed to achieve a smooth closure and better cosmetic outcome.

• Histological testing — in both lipoma and cyst removal, the excised tissue is often sent for laboratory analysis (biopsy) to confirm the diagnosis and rule out rare malignant conditions such as liposarcoma or other soft-tissue tumours.

In most cases, these procedures are straightforward and performed under local anaesthesia. Recovery is quick and recurrence is uncommon when the capsule or entire mass is fully removed.

What is the recovery and aftercare like for lipomas and sebaceous cysts?

Recovery after lipoma or sebaceous (epidermoid) cyst removal is usually smooth and uncomplicated. Most procedures are done under local anaesthesia, allowing you to return home the same day. Healing time varies slightly depending on the size and location of the lump, as well as the technique used for removal.

• Immediate recovery — mild soreness, swelling or bruising around the surgical site is common for a few days. Your doctor may prescribe pain relief or antibiotics if necessary. Dressings are typically kept in place for the first 24 to 48 hours to protect the wound and prevent infection.

• Wound care — keep the incision area clean and dry. You may gently wash it after 48 hours unless otherwise instructed. Avoid soaking the wound or exposing it to pools or saunas until it has healed completely. Your doctor will advise when to remove or change dressings.

• Stitches — dissolvable sutures are usually used and will gradually disappear on their own over the next few weeks.

• Activity level — most patients resume light daily activities within one to two days. Strenuous exercise or heavy lifting should be avoided until your doctor confirms complete healing, as excessive tension may widen the scar or delay closure.

• Scar care — once the incision has fully closed, you can use silicone gel or sheets to minimise scarring. Regular sun protection also helps prevent pigmentation changes along the healed wound.

• Follow-up review — your doctor will review the surgical site to ensure proper healing and discuss the results of the tissue analysis. Incomplete capsule removal is rare but can occasionally cause recurrence, so follow-up helps ensure long-term success.

With proper care, recovery after lipoma or sebaceous cyst removal is quick, and recurrence is uncommon when the lesion is completely excised.

Can lipomas and sebaceous cysts come back after removal?

Both lipomas and sebaceous (epidermoid) cysts can occasionally recur, but recurrence is uncommon when the entire lesion, including its capsule, has been completely removed. The likelihood of regrowth depends on the removal method and underlying factors that may predispose a person to these conditions.

• Lipoma recurrence — lipomas rarely come back once they are fully excised along with the fibrous capsule surrounding the fatty tissue. However, if the capsule is left behind or if a person has an inherited tendency such as multiple hereditary lipomatosis, new lipomas may appear elsewhere on the body over time. Liposuction procedures, while less invasive, carry a higher recurrence rate because the capsule may not be completely removed.

• Sebaceous (epidermoid) cyst recurrence — recurrence is more likely if the cyst capsule is not removed in its entirety. This often happens when a cyst is drained during an active infection, as inflammation makes the cyst wall fragile and more difficult to remove completely. Once the infection subsides, definitive surgical excision is recommended to prevent it from reforming.

• Other contributing factors — repeated trauma or irritation to the same area can trigger the development of new cysts or lipomas. Individuals with oily skin or chronic follicular blockage may also be more prone to cyst recurrence.

In most cases, surgical removal is curative and recurrence rates remain very low when proper technique and aftercare are followed. Regular follow-up ensures that any new or recurrent lesions are identified and treated early.

When should you see a doctor for lipomas or sebaceous cysts?

Most lipomas and sebaceous (epidermoid) cysts are harmless and do not require urgent medical attention. However, certain changes or symptoms warrant a prompt review by a doctor to ensure the lump is benign and to prevent complications such as infection or abscess formation.

• Rapid growth — if a lump increases noticeably in size over a short period, it should be evaluated to rule out other soft-tissue conditions such as liposarcoma.

• Pain or tenderness — a lipoma or cyst that becomes painful may be pressing on nearby nerves, inflamed or infected. Early treatment helps prevent further irritation or abscess formation.

• Redness, swelling or discharge — these are signs of infection or cyst rupture. Medical attention is necessary for drainage, antibiotics and possible follow-up excision after the inflammation has settled.

• Changes in colour or texture — a lump that feels hard, irregular or fixed to deeper tissues needs further assessment to exclude malignancy.

• Interference with daily activities — lesions near joints, under straps or along pressure points can cause discomfort and may benefit from removal for functional reasons.

• Uncertainty about diagnosis — any new lump or one that looks different from previous ones, should be examined by a healthcare professional to confirm its nature and decide whether treatment is required.

Early evaluation not only confirms that the lump is benign but also allows for a simple, minimally invasive procedure if removal becomes necessary.

Summary

Skin lumps such as lipomas and sebaceous (epidermoid) cysts are common, slow-growing and usually benign. They develop beneath the skin due to overgrowth of fatty tissue or blockage of hair follicles. While most remain painless and harmless, some may enlarge, become infected or cause cosmetic concern over time. A medical assessment helps confirm that a lump is non-cancerous and determine whether removal is advisable. 

Most cases are diagnosed through physical examination, with imaging or biopsy performed when further clarity is needed. Treatment, when required, is simple and involves minor surgical excision under local anaesthesia. Complete removal of the lesion and its capsule prevents recurrence and offers an excellent cosmetic outcome. With proper aftercare, recovery is quick and uneventful and the risk of complications is low. Maintaining good skin hygiene and seeking timely medical review for new or changing lumps ensures long-term skin health and peace of mind.

If you have noticed a lump that is growing, painful or frequently inflamed, schedule a consultation with Tan Siong San Surgery for an accurate diagnosis and personalised treatment plan.