OVERVIEW

What is infantile perianal pyramidal protrusion?

Infantile perianal pyramidal protrusion (IPPP) is a benign perianal lesion, also known as infantile perianal wedge-shaped protrusion, and has been described as a skin tag or skin fold.

It is clinically rare, with almost all cases occurring in girls, typically during infancy or early childhood, and is uncommon after the age of 3.

The lesion usually appears as a pedunculated, cone-shaped protrusion with a smooth surface, red or rosy in color, and is non-tender. Treatment is generally unnecessary. The clinical course involves recurrent swelling, but the lesion eventually resolves.

It may be associated with constipation, diaper dermatitis, lichen sclerosus, or other irritations, but the resolution of the lesion does not coincide with the disappearance of these conditions.

SYMPTOMS

What are the manifestations of infantile perianal pyramidal protrusion?

It is often accidentally discovered by parents as a "fleshy growth" near the baby's anus, which may be present at birth or appear during infancy. The condition shows a strong female predominance, with almost all clinical cases occurring in girls.

The characteristic feature is a single protrusion of 5–30 mm around the anus, typically pyramidal in shape (Figure 1), most commonly located anterior to the midline of the anus, between the anus and perineum, closely adjacent to the anus.

There have also been reports of posterior lesions or even both anterior and posterior occurrences, with non-midline locations being rare.

The surface of the protrusion is smooth, appearing pale red, red, or rosy in color, soft and elastic to the touch, with no pain, inguinal lymphadenopathy, or other discomfort symptoms.

Apart from the anal lesion, there are generally no other systemic abnormalities. It may be associated with conditions such as constipation, diaper dermatitis, or lichen sclerosus, but can also occur without any prior medical history.

(Figure 1, photo source: Reference [1])

Some scholars refer to this condition as "infantile protrusion" because it is not always pyramidal in shape; it can also be tongue-shaped, wedge-shaped, pyramid-shaped, papular, peanut-shaped, etc.

CAUSES

What causes infant perianal pyramidal protrusion?

Infant perianal pyramidal protrusion is a benign dermatological condition first reported by Kayashima et al. in 1996. The exact pathogenesis remains unclear, but most experts attribute the lesion to the following factors:

• Congenital: Originating from remnants of the embryonic urogenital septum; or congenital midline weakness. The frequent discovery of lesions following constipation episodes also supports the theory of congenital midline weakness in the sensitive perineal region.

• Acquired: Secondary to mechanical friction irritation, associated with diarrhea, fistulas, anal fissures, and diaper dermatitis.

• Related to fibrous tissue rearrangement caused by inflammation associated with lichen sclerosus.

DIAGNOSIS

How to diagnose perianal pyramidal protrusion in infants?

Diagnosis is typically based on clinical presentation; presence of related causative factors can support the diagnosis.

Is testing necessary for perianal pyramidal protrusion in infants?

Generally, no testing is required.

In special cases, dermoscopy may help differentiate it from other conditions. Dermoscopic findings of perianal pyramidal protrusion show: structureless white areas and vascular patterns composed of red globules and dotted vessels.

What conditions should perianal pyramidal protrusion be distinguished from?

Differential diagnoses include rectal prolapse, perianal Crohn's disease, condyloma acuminatum, hemangioma, hemorrhoids, and even sexual abuse.

These conditions can be clinically differentiated based on age of onset, symptoms, medical history, and physical examination. Suspicious cases may require ultrasound or dermoscopy for further evaluation.

TREATMENT

Where to seek medical attention for infant perianal pyramidal protrusion?

Pediatrics, proctology, or dermatology

How to treat infant perianal pyramidal protrusion?

IPPP usually does not require treatment and may resolve on its own over time, ranging from months to years. Reducing local friction can promote resolution—apply petroleum jelly after each bowel movement or urination, as often as needed. Clean the area gently with baby wipes to minimize irritation.

If accompanied by conditions like constipation, diarrhea, or diaper rash, targeted treatment may be necessary.

Are there any adverse consequences if infant perianal pyramidal protrusion is left untreated?

IPPP itself does not require treatment or may only need friction reduction, with no adverse consequences.

However, if IPPP is caused by underlying conditions such as constipation, diaper rash, or lichen sclerosus, treating the primary condition is essential to avoid unnecessary complications.

DIET & LIFESTYLE

What should infants with perianal pyramidal protrusion pay attention to in their diet?

There are no specific dietary restrictions. A healthy and balanced diet is sufficient. Pay attention to dietary proportion and consume high-fiber foods appropriately to prevent constipation.

What should infants with perianal pyramidal protrusion pay attention to in daily life?

There are no special precautions in daily life. IPPP does not affect daily activities.

PREVENTION

Can Infant Perianal Pyramidal Protrusion Be Prevented?

Acquired IPPP can be reduced by preventing constipation, diaper rash, and practicing proper perianal hygiene.

• Maintain a balanced diet with adequate fiber intake; older toddlers should develop regular bowel habits to prevent constipation.

• Change diapers promptly after each bowel movement or urination, keep the area clean and dry, and apply moisturizing petroleum jelly to prevent diaper rash.

• During diarrhea, enhance buttock care with frequent changes, gentle wiping, and routine moisturizing. Use diaper cream if redness occurs.