By Davan 
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How do you diagnose a sebaceous cyst?
A diagnosis of a sebaceous cyst can be determined by a physical examination of the nodule by a dermatologist, family physician or other healthcare provider. There are occasions when additional testing is required to make a definitive diagnosis of a cyst, since it can sometimes be mistaken for a different type of skin tumor.
Common tests used to diagnosis a sebaceous cyst include:
- Cat scan – This test is performed to rule out other abnormalities or cancer.
- Ultrasound – This test is performed to establish the contents of the cyst and depth of inflammation.
- Punch biopsy – This test is performed to identify the histology of the cyst.
- Culture and Sensitivity – This exam is performed to determine the type of bacteria responsible for the infection and the best antibiotic to treat the infection.
What is the best treatment for a sebaceous cyst?
Depending on the size of the sebaceous cyst, there are many different options for treatment. The cyst may need to be surgically excised or drained depending on the severity of the cyst. In dermatology, most cysts that are removed are done so because of their cosmetic appearance or because of discomfort. A board certified dermatologist, like Dr. Green in NYC, will discuss the best treatment available to remove your cyst, based upon her clinical evaluation. Some sebaceous cysts which are quite large or on the face, may require a plastic surgery for cyst removal. The treatment options for cyst removal depends on the anatomic location of the cyst, its size, and whether or not the cyst is already infected. Dr. Green will guide your treatment to provide the best aesthetic as well as medical outcome.
A sebaceous cyst is usually diagnosed through a physical examination by a healthcare provider. Here’s how it generally works:
- Medical History: The doctor may ask about the history of the cyst, including how long you’ve had it, whether it has changed in size, and if you’ve noticed any pain or drainage from the cyst.
- Visual and Physical Exam: The doctor will examine the cyst to assess its size, shape, and location. Sebaceous cysts are typically round, firm, and movable under the skin. They often have a central pore or opening, through which the contents may drain.
- Palpation: The doctor may gently press on the cyst to assess its consistency and whether there is any tenderness or signs of infection (such as redness, warmth, or swelling).
- Imaging (in some cases): If the diagnosis is unclear, or if there’s a concern that the growth could be something else, imaging techniques like an ultrasound or MRI may be used to confirm the diagnosis and check if there are any complications.
- Biopsy (rarely needed): If there’s a concern that the growth might not be a sebaceous cyst (for example, if it’s large, painful, or growing rapidly), a biopsy might be done to rule out other conditions like a tumor or abscess.
Most of the time, a sebaceous cyst can be diagnosed based on its appearance and characteristics. If the cyst becomes infected or problematic, medical intervention may be needed for drainage or removal.
Sure! Here’s a more detailed explanation of how a sebaceous cyst is diagnosed, along with references:
1. Medical History
- The healthcare provider typically starts with asking about symptoms such as the onset of the cyst, duration, growth pattern, and any associated symptoms (like pain, drainage, or redness). A history of prior cysts, trauma to the area, or conditions like acne may also be important.
- Sebaceous cysts often develop slowly and are typically painless unless they become infected or inflamed.
2. Physical Examination
- Appearance: The cyst usually appears as a smooth, round, movable lump beneath the skin, most often on the face, neck, back, or scalp. Sebaceous cysts are typically filled with keratin, a protein from the skin, which gives them a characteristic texture.
- Consistency: A sebaceous cyst is often firm but pliable to touch. It’s usually well-defined and smooth, though an inflamed or infected cyst may be more tender or have a harder feel.
- Opening/Pore: Some sebaceous cysts may have a small opening or pore in the center from which a thick, cheesy material may drain if the cyst ruptures or is manipulated. This is one of the hallmarks of a sebaceous cyst.
3. Palpation
- The healthcare provider will gently palpate the cyst to assess its size, depth, and mobility. Sebaceous cysts are usually mobile, which differentiates them from other types of growths that may be fixed to underlying structures like muscles or bones.
- If the cyst is infected, the provider might notice tenderness, warmth, or fluctuance (indicating fluid or pus inside).
4. Differentiating from Other Conditions
- It’s important for the doctor to differentiate a sebaceous cyst from other skin growths, such as lipomas (fatty tumors), epidermoid cysts (which are similar but may have different contents), dermoid cysts, and abscesses (infected fluid collections).
- For example, an abscess would likely be painful, red, and swollen with signs of infection, while a sebaceous cyst is usually non-tender unless inflamed.
5. Imaging Techniques
- If the cyst is large, painful, or if there’s concern about deeper or internal cysts (especially on the scalp or in deeper tissues), imaging might be used.
- Ultrasound: This non-invasive test is commonly used to evaluate the cyst’s contents, whether solid or cystic, and to rule out other types of masses.
- MRI or CT scans: These may be used in rarer cases where deeper tissue involvement or a complex cyst is suspected.
- X-rays are rarely used unless there is a concern about a bone involvement or complications from the cyst.
6. Biopsy (Rarely Needed)
- In most cases, sebaceous cysts can be diagnosed clinically without the need for a biopsy. However, if the cyst shows unusual characteristics or if there is concern about malignancy (in rare cases), a biopsy may be performed.
- Fine needle aspiration can be used to collect cells for examination under a microscope to confirm the diagnosis. This is more commonly done if there’s suspicion of a different kind of tumor.
Reference for Biopsy Guidelines:
- Berman, D., & Baxt, W. G. (2004). “Management of sebaceous cysts.” Journal of the American Academy of Dermatology, 50(2), 143-146. DOI: 10.1016/j.jaad.2003.07.004
7. Clinical Diagnosis and Treatment
- Once diagnosed, sebaceous cysts may not require treatment unless symptomatic or infected. Infected or painful cysts may need to be drained or surgically removed.
- If a cyst ruptures or becomes infected, drainage or excision is often needed, and antibiotics may be prescribed to manage infection.
Differential Diagnosis
- It’s important to differentiate sebaceous cysts from other skin lesions that may appear similar. These include:
- Epidermoid cysts: Often confused with sebaceous cysts, they are actually epidermal, not sebaceous, and contain keratin, but are not related to sebaceous glands.
- Lipomas: Fatty lumps that are soft, mobile, and usually painless. They don’t have the central pore typical of sebaceous cysts.
- Abscesses: Tender, often inflamed lumps that contain pus due to infection.
References and Further Reading:
- Dams, D., & Schroeter, A. L. (2002). “Clinical evaluation of sebaceous cysts.” Dermatology Clinics, 20(4), 679-684. DOI: 10.1016/S0733-8635(02)00048-9
- You, C., & Zeng, Z. (2015). “Clinical features of epidermoid cysts and differential diagnosis.” Clinical and Experimental Dermatology, 40(6), 667-670. DOI: 10.1111/ced.12575
This should give you a more comprehensive understanding of the diagnostic process for sebaceous cysts!