Pilonidal Sinus Differential Diagnosis: What Else Could It Be?
You probably can't tell just by looking whether you have a pilonidal sinus. In fact, even doctors can't always tell with a physical exam alone. That's because the pilonidal sinus differential diagnosis list is extensive.
If you have pain or discharge around the cleft of your buttocks, read on to see what the cause might be.
What Other Conditions Produce Similar Symptoms?
Because they present with similar symptoms, differentiating between pilonidal sinus, hidradenitis suppurativa and anal fissure can be difficult. The doctor must take great care to determine which of those three conditions a patient has.
To further complicate matters, there are other less common conditions that can present with similar symptoms.
Ahead, learn about the most common pilonidal sinus differential diagnosis options as well as many of the not-so-common ones.
Hidradenitis Suppurativa
Bumps that look like pimples but occur in unusual places for acne to appear may turn out to be caused by a skin condition called hidradenitis suppurativa. Although these lesions can occur throughout the body, they most often appear in the underarms or groin.
The bumps can increase in size and may be painful. When they rupture, they may leak blood and pus, which further contributes to the difficulty in distinguishing hidradenitis suppurativa from a pilonidal sinus.
Untreated hidradenitis suppurativa can cause thick, restrictive scarring. Therefore, a proper diagnosis is imperative.
Anal Fistula
A pilonidal sinus and an anal fistula can look very similar. Both are associated with abscesses in the region, and both involve an unnatural channel through the tissue. There can be drainage and pain with both. However, in a pilonidal sinus, the tract leads to a collection of hair and debris while the tract of a fistula extends from the skin all the way to the anal wall.
Anoscopy can typically be used to distinguish pilonidal sinus from anal fistula. Sometimes, however, a final diagnosis cannot be made until surgery is performed.
In the video Pilonidal Sinus Resembling Fistula in Ano, learn more about how these two conditions can often be mistaken for one another.
Pyoderma Gangrenosum
What appears to be the opening to a pilonidal sinus could turn out to be pyoderma gangrenosum, a serious condition that causes ulcers on the skin. The patient starts with small ulcers that join to form one larger wound, which is usually rimmed with blue or purple. Pyoderma gangrenosum is painful and can result in scarring.
Although pyoderma gangrenosum most often presents on the legs, it can occur anywhere on the body, including the anal region.
Early diagnosis of pyoderma gangrenosum is imperative because starting immunosuppression treatment as soon as possible can reduce scarring.
Sacral Osteomyelitis
In general, osteomyelitis is a bone infection. The lowest portion of the spine is the sacrum, so sacral osteomyelitis refers to a bone infection in that part of the spine.
Because the sacrum is close to the rectum, sacral osteomyelitis can be mistaken for a pilonidal sinus. The two conditions share some overlapping symptoms: pain, redness and swelling.
Osteomyelitis requires powerful antibiotics. Some cases necessitate surgery.
Presacral Tumor
The space between the end of the spine and the rectum is known as the presacral or retrorectal space. Although rare, benign or malignant tumors can develop in this area. Presacral tumors can cause pain in the same region that is affected by pilonidal disease.
There have been cases in which people who were thought to have recurrent pilonidal disease were actually suffering from a presacral tumor. Often, a definitive tumor diagnosis cannot be made until the mass is surgically removed, but MRIs or CT scans can provide useful clues.
Abscess
Although pilonidal disease can be associated with abscesses, not all abscesses in the region can be classified as pilonidal. If the abscess is elsewhere in the perirectal region and not in the cleft of the buttocks, it will receive a different diagnosis.
Dorsal Dermal Sinus
Some people are born with a congenital condition called dorsal dermal sinus, in which a tract connects the spine to the skin. This sinus may be mistaken for a pilonidal sinus.
Although most cases of dorsal dermal sinus are detected early in life, some may be discovered when a pilonidal sinus is suspected. Doctors can perform an ultrasound to determine whether a patient's tract is a dorsal dermal sinus.
How Can a Diagnosis of Pilonidal Sinus Be Made?
The primary means used for diagnosing pilonidal disease is a physical examination by a doctor. The doctor will look for an opening at the skin and should be able to feel a mass beneath the skin.
The patient's history can provide further information that can help with the diagnosis, so the doctor may ask questions about whether the patient has experienced:
In some cases, the doctor may need more information before returning a diagnosis. A CT scan may help distinguish pilonidal disease from other conditions.
Pilonidal sinus differential diagnosis is important because many conditions have similar symptoms, but their necessary treatments are quite different. After proper diagnosis, a doctor can perform laser treatment to heal a pilonidal sinus or treat a different condition with medication, surgery or other therapies.
