3-1. How to tell the difference Will it develop into malignant cancer?

Characteristics of sebum include the following:

• The skin is slightly raised, and there is a lump of a few millimeters to a few centimeters.
• A black dot (opening) in the center of the lump
• Sometimes something smells bad
• It is not painful or itchy, but when it becomes inflamed it becomes red, swollen, and painful.
• If inflammation is left untreated, it will burst and pus will come out.

Basically, if the cyst is not completely removed, it will recur. It has been reported that if left untreated and inflammation continues, it can develop into cancer, but this is extremely rare.https://www.ncbi.nlm.nih.gov/pubmed/29681810)

3-2. I have painful lumps or boils on my buttocks, groin, pubic area, groin, or thighs.

Painful growths that appear in these areas are often not sebaceous cysts, so care should be taken. They may be a skin disease called hidradenitis suppurativa, which is likely to occur on the buttocks, groin, armpits, under the breasts, and around the anus. Antibiotics (oral anti-suppurative medications) can alleviate the symptoms, but they do not cure completely, and surgery to remove the affected area with a scalpel may be necessary. In severe cases, biological agents are prescribed. The cause is largely unknown, and it is said that genetics, smoking, obesity, bacteria, mechanical irritation, and hormones are all involved. An ultrasound examination can clearly distinguish it from a sebaceous cyst. The areas where it is likely to appear are shown below.

If the growths are in the genital area, people are embarrassed to come to the doctor and endure it until it gets worse. If it is in the early stages, it can be easily treated, so please come in early.>> Kamogawa Clinic Tenroku

Hidradenitis Suppurativa Stages and Severity (kingslun.com)　 Journal of the Japanese Dermatological Association, Vol. 131, No. 1 (jst.go.jp)

3-3. I can't tell the difference between this and other bumps or lumps

There are calcifying epithelioma, lipoma, ganglion, sebaceous cystoma, dermoid cyst, neurilemmoma, preauricular fistula, etc. In rare cases, there are malignant ones such as cancer. Doctors can easily distinguish them when they see them, but it is difficult to explain them to patients.

If you would like to know more, please click on the following link:

Calcifying epitheliomaCalcific epithelioma | Japanese Society of Plastic Surgery (jsprs.or.jp)
Lipoma,Lipoma | Japanese Society of Plastic Surgery (jsprs.or.jp)
Ganglion5gangurion.pdf (jssh.or.jp)
Sebaceous cystosis
Dermoid cystDermoid Cyst | Japan Society of Plastic and Reconstructive Surgery (jsprs.or.jp)
Schwannoma
Pilonidal sinus
Preauricular fistulaEar (anterior) fistula | Japanese Society of Plastic Surgery (jsprs.or.jp)

Pilonidal sinus
A pilonidal sinus that develops in the buttocks is a small hole that mainly occurs in the skin just above the anus (on the midline of the sacrococcygeal region) and contains hair. It often develops in the buttocks of men who spend a lot of time sitting, such as when driving for long periods of time, and who are also hirsute, but it can affect both men and women. It can also develop in other places besides the buttocks, such as the armpits. There was previously a debate over whether it is congenital or acquired, but it is now thought to be caused by body hair penetrating the skin later in life. It is usually asymptomatic, but if an infection occurs, pain and swelling may occur and pus may come out. It can be mistaken for anal fistula or a suppurating skin tumor. (The patient in the photo on the left came to see us because he had suddenly developed swelling and pain five days ago.)
>>Kamogawa Clinic Tenroku

>>Click here for an article summarizing sebaceous cysts