What is Dissecting Cellulitis of the Scalp (PCAS)?

What is Dissecting Cellulitis of the Scalp (PCAS)

Dissecting Cellulitis of the Scalp also known as Perifolliculitis capitis abscedens et suffodiens (PCAS) is a rare scalp disease. The main cause of this challenging condition is an infection of the scalp. This disease is usually long-lasting, but it may wax and wane with periods of inactivity, or remissions. It can also lead to local disfiguring complications such as scarring and hair loss.

Dissecting Cellulitis of the Scalp is different from the most common types of cellulitis infections.

In this article, we will provide more details about its manifestations. Also, we will explain the standard treatment and prevention methods.



There remain some gaps in understanding the primary causes of this condition. It involves infection with the destruction of the hair follicles and ultimately, important scarring.



The signs of the disease may vary from one case to the other. The most common symptoms are outbreaks involving the deep layers of the scalp. They may appear as nodules or abscesses distributed in a patchy fashion. These lesions are tender and painful and lead to the formation of crusts at the surface of the scalp.

The presentation of crusts on the scalp is the main symptom of this condition. Flare-ups and outbreaks are common symptoms of this chronic condition.



Any of the above symptoms need medical attention. A doctor can make an accurate diagnosis. But, due to the rare nature of the disease, a misdiagnosis can sometimes occur. Indeed, it can be difficult to confirm a PCAS with an initial checkup. Testing of the areas of outbreaks may be necessary to rule out other conditions.

A doctor will ask questions about the health of the affected individuals. He/she will also take a look at their full medical history. This information allows the medical professional to rule out other scalp or skin diseases.

The diagnosis process for PCAS can be longer than for the common forms of cellulitis. This is mainly due to the rare prevalence and to the complexity of PCAS. Additionally, there are other conditions with similar symptoms.



There is no definitive cure for this chronic condition. Thus, treatment aims at the reduction of the impact of the symptoms and at the prevention of the complications. One common form of treatment for dissecting cellulitis of the scalp is a course of antibiotics, to treat the infection, combined with anti-inflammatory drugs.

It is essential to follow the doctor’s instructions. You should always finish a course of antibiotics.

Since the lesions can be painful and itchy, topical steroids are prescribed; steroids will also help to reduce inflammation and minimize by the same token the damage to the hair follicles, which can later result in hair loss.

For these reasons, appropriate and well-monitored use of topical steroids can dramatically improve the quality of life of affected patients.

The main focus of treatment is reducing the possibility of outbreaks. This implies specialist care and regular check-ups.

Although, there is no permanent cure for this disease, a careful management plan can help to optimize the quality of life of patients.

Severe acute flares may need to be treated with systemic corticosteroids; specific surgical procedures may be recommended once the condition is considered in remission.

The prevention of relapses is another aim of novel therapies. New treatments make use of specific types of blockers of inflammation; encouraging results with TNF-α inhibitors have been reported in the medical literature,



This disease is rare. However, it is more prevalent in certain groups of populations. African American and Hispanic Males in the age range of 18-40 years are at an increased risk of having PCAS.

Some useful precautions such as following basic hygiene precautions can contribute to decrease this risk. Maintain your scalp reasonably clean with regular washing. Avoid using too many and harsh hygienic products in order to preserve the delicate balance of the normal skin microbiota and eliminate the risk of an added allergic reaction.



This rare, yet chronic condition can lead to disfiguring scars. Fortunately, there are certain forms of treatment which can help to ease the symptoms and reduce the complications.

Image credit: Deposit.Photos.com

Last article update: 9/10/2019

Medically reviewed by Dr. Thouria Bensaoula on Sept 10, 2019.