Medical Conditions

My Baby Has a Lump on the Side of Their Neck (Branchial Cleft Cyst)

Medically reviewed by Dr. Michael Okonkwo, MD, FAAP · Board-Certified Neonatologist

Content reviewed against published AAP, Mayo Clinic, NIH guidelines

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If your baby has been diagnosed with or you suspect has a lump on the side of their neck (branchial cleft cyst), here is what the evidence says.

The short answer

A branchial cleft cyst is a congenital lump that appears on the side of the neck, usually along the front edge of the sternocleidomastoid muscle. It develops from remnants of embryonic structures (branchial arches) that did not fully resolve during fetal development. The cyst is typically painless and may be noticed at birth or later in childhood, often when it becomes infected. Surgical removal is the recommended treatment.

Key takeaways

  • A branchial cleft cyst is a congenital lump that appears on the side of the neck, usually along the front edge of the sternocleidomastoid muscle. It develops from remnants of embryonic structures (branchial arches) that did not fully resolve during fetal development. The cyst is typically painless and may be noticed at birth or later in childhood, often when it becomes infected. Surgical removal is the recommended treatment.
  • Usually normal when: A small, painless lateral neck lump that has been diagnosed as a branchial cleft cyst and is being monitored
  • Call your doctor if: The cyst becomes rapidly swollen, red, warm, and painful (infected cyst requiring antibiotics)
  • Varies by age — see the age-by-age breakdown below
“Fever itself is not an illness — rather, it is a sign or symptom that the body is fighting an infection. Fever stimulates certain defenses, such as the white blood cells, which attack and destroy invading bacteria.”
— Fever and Your Child, American Academy of Pediatrics (AAP)

This is one of the most common questions parents ask. Searching for answers means you care.

What Parents Should Know

According to AAP, Mayo Clinic, NIH guidelines, a branchial cleft cyst is a congenital lump that appears on the side of the neck, usually along the front edge of the sternocleidomastoid muscle. It develops from remnants of embryonic structures (branchial arches) that did not fully resolve during fetal development. The cyst is typically painless and may be noticed at birth or later in childhood, often when it becomes infected. Surgical removal is the recommended treatment. At 0-3 months, branchial cleft cysts may be present at birth as a painless, soft lump on the side of the neck, or as a small pit or sinus opening on the skin. Your pediatrician will evaluate the mass with ultrasound to confirm the diagnosis. In the absence of infection, surgery is typically planned electively rather than urgently. It is generally considered normal when a small, painless lateral neck lump that has been diagnosed as a branchial cleft cyst and is being monitored. However, you should contact your pediatrician promptly if the cyst becomes rapidly swollen, red, warm, and painful (infected cyst requiring antibiotics).

Sources: [1], [2], [3]

Normal vs. Concerning

Usually Normal
Worth Discussing
A small, painless lateral neck lump that has been diagnosed as a branchial cleft cyst and is being monitored
The cyst becomes rapidly swollen, red, warm, and painful (infected cyst requiring antibiotics)
Your pediatric surgeon has scheduled elective removal
A neck mass is hard, rapidly growing, or accompanied by other concerning symptoms
A small skin pit on the side of the neck without drainage or swelling
You notice a new lump on the side of your baby's neck

By Age

What to expect by age

0-3 months

Branchial cleft cysts may be present at birth as a painless, soft lump on the side of the neck, or as a small pit or sinus opening on the skin. Your pediatrician will evaluate the mass with ultrasound to confirm the diagnosis. In the absence of infection, surgery is typically planned electively rather than urgently.

3-12 months

The cyst may remain stable in size or grow gradually. It often comes to attention when it becomes infected during an upper respiratory illness, becoming red, swollen, and tender. Infected cysts are treated with antibiotics first, followed by surgical removal after the infection clears. Some branchial cleft anomalies include a fistula (tract) that opens to the skin surface.

12-24 months

If surgery has been recommended, this is a common age to proceed. The operation removes the cyst and any associated tract to prevent recurrence and future infections. Recovery is typically 1-2 weeks. The surgical scar usually heals well and becomes less visible over time.

2-3 years

Branchial cleft cysts that were not noticed earlier may become apparent during this period, especially if they become infected. A lateral neck mass in a toddler that fluctuates in size may be a branchial cleft cyst that periodically fills and drains through a sinus tract. Definitive surgical management prevents further episodes.

3-5 years

Some branchial cleft cysts are first discovered at preschool age. The recommendation for surgical removal remains the same to prevent recurrent infections. Before surgery, imaging (ultrasound or MRI) maps the extent of the cyst and any associated tracts to guide the surgical approach.

What to Tell Your Pediatrician

  • Describe when you first noticed has a lump on the side of their neck (branchial cleft cyst) and how it has changed over time.
  • Note your baby's current age and which age-specific patterns you are seeing.
  • Mention if you notice a new lump on the side of your baby's neck.
  • Mention if a known branchial cleft cyst seems to be growing.
  • Let your doctor know if you have noticed any related concerns, such as changes in feeding, sleep, or movement patterns.
  • Bring a list of any questions or observations you want to discuss at the appointment.

What Should You Do?

When to take action

Probably normal when...
  • A small, painless lateral neck lump that has been diagnosed as a branchial cleft cyst and is being monitored
  • Your pediatric surgeon has scheduled elective removal
  • A small skin pit on the side of the neck without drainage or swelling
Mention at your next visit when...
  • You notice a new lump on the side of your baby's neck
  • A known branchial cleft cyst seems to be growing
  • There is intermittent drainage from a small opening on the neck
Act now when...
  • The cyst becomes rapidly swollen, red, warm, and painful (infected cyst requiring antibiotics)
  • A neck mass is hard, rapidly growing, or accompanied by other concerning symptoms

What You Can Do at Home

  • Keep track of when you notice has a lump on the side of their neck (branchial cleft cyst) — noting the time of day, duration, and any triggers can help your pediatrician.
  • Remember that a small, painless lateral neck lump that has been diagnosed as a branchial cleft cyst and is being monitored — this is generally within the range of normal.
  • At 0-3 months, focus on observation rather than intervention unless your pediatrician advises otherwise.
  • Follow any care instructions from your pediatrician. Keep a written log of symptoms to bring to appointments.
  • While monitoring at home, seek immediate care if the cyst becomes rapidly swollen, red, warm, and painful (infected cyst requiring antibiotics).

My Baby Has a Lump in the Middle of Their Neck (Thyroglossal Duct Cyst)

A thyroglossal duct cyst is the most common congenital midline neck mass in children. It appears as a painless, round lump in the middle of the neck, usually near or below the hyoid bone (the bone you can feel at the base of the tongue area). It characteristically moves upward when the child swallows or sticks out their tongue. While usually harmless, surgical removal is recommended because these cysts can become infected.

My Baby Has Swollen Lymph Nodes in Their Neck

Swollen neck lymph nodes (cervical lymphadenopathy) are extremely common in babies and young children and are almost always caused by routine infections like colds, ear infections, or throat infections. Neck nodes up to 1 cm are generally considered normal in children. They may enlarge during infections and take weeks to return to normal size. Most are harmless, but nodes that are very large, hard, fixed, or associated with other concerning symptoms need evaluation.

When Should My Baby See a Pediatric ENT?

A pediatric ENT (otolaryngologist) specializes in ear, nose, and throat conditions in children. Common reasons for referral include recurrent ear infections (3+ in 6 months or 4+ in a year), hearing loss, chronic ear fluid, enlarged tonsils or adenoids causing sleep or breathing problems, stridor, chronic sinusitis, airway abnormalities, and neck masses. These specialists can perform ear tube surgery, tonsillectomy, adenoidectomy, and airway evaluations.

Milestone

Month-by-Month Development

Detailed monthly development guides from birth through 24 months.

Guide

When to Call the Doctor

General guide on when to call the pediatrician, visit urgent care, or go to the ER.

Frequently asked questions

Is has a lump on the side of their neck (branchial cleft cyst) normal?
A branchial cleft cyst is a congenital lump that appears on the side of the neck, usually along the front edge of the sternocleidomastoid muscle. It develops from remnants of embryonic structures (branchial arches) that did not fully resolve during fetal development. The cyst is typically painless and may be noticed at birth or later in childhood, often when it becomes infected. Surgical removal is the recommended treatment.
When should I call the doctor about has a lump on the side of their neck (branchial cleft cyst)?
The cyst becomes rapidly swollen, red, warm, and painful (infected cyst requiring antibiotics) A neck mass is hard, rapidly growing, or accompanied by other concerning symptoms
When is has a lump on the side of their neck (branchial cleft cyst) normal?
A small, painless lateral neck lump that has been diagnosed as a branchial cleft cyst and is being monitored Your pediatric surgeon has scheduled elective removal A small skin pit on the side of the neck without drainage or swelling
What causes has a lump on the side of their neck (branchial cleft cyst)?
A branchial cleft cyst is a congenital lump that appears on the side of the neck, usually along the front edge of the sternocleidomastoid muscle. It develops from remnants of embryonic structures (branchial arches) that did not fully resolve during fetal development. The cyst is typically painless and may be noticed at birth or later in childhood, often when it becomes infected. Surgical removal is the recommended treatment. Common explanations include: A small, painless lateral neck lump that has been diagnosed as a branchial cleft cyst and is being monitored. Your pediatric surgeon has scheduled elective removal.
What should I mention to my pediatrician about has a lump on the side of their neck (branchial cleft cyst)?
You should mention has a lump on the side of their neck (branchial cleft cyst) at your next visit if: You notice a new lump on the side of your baby's neck. A known branchial cleft cyst seems to be growing. There is intermittent drainage from a small opening on the neck.
Is has a lump on the side of their neck (branchial cleft cyst) normal at 0-3 months?
Branchial cleft cysts may be present at birth as a painless, soft lump on the side of the neck, or as a small pit or sinus opening on the skin. Your pediatrician will evaluate the mass with ultrasound to confirm the diagnosis. In the absence of infection, surgery is typically planned electively rather than urgently.
Is has a lump on the side of their neck (branchial cleft cyst) normal at 3-12 months?
The cyst may remain stable in size or grow gradually. It often comes to attention when it becomes infected during an upper respiratory illness, becoming red, swollen, and tender. Infected cysts are treated with antibiotics first, followed by surgical removal after the infection clears. Some branchial cleft anomalies include a fistula (tract) that opens to the skin surface.
Should I go to the ER for has a lump on the side of their neck (branchial cleft cyst)?
Seek emergency care if the cyst becomes rapidly swollen, red, warm, and painful (infected cyst requiring antibiotics), or if a neck mass is hard, rapidly growing, or accompanied by other concerning symptoms. When in doubt, call your pediatrician's after-hours line for guidance.
Does has a lump on the side of their neck (branchial cleft cyst) go away on its own?
In many cases, has a lump on the side of their neck (branchial cleft cyst) resolves on its own, especially when a small, painless lateral neck lump that has been diagnosed as a branchial cleft cyst and is being monitored. By 3-5 years, some branchial cleft cysts are first discovered at preschool age. The recommendation for surgical removal remains the same to prevent recurrent infections. Before surgery, imaging (ultrasound or MRI) maps the extent of the cyst and any associated tracts to guide the surgical approach.
AAPMAYO CLINICNIH

References

  1. [1]American Academy of Pediatrics. Neck Masses in Children. Pediatrics in Review. AAP
  2. [2]Mayo Clinic. Branchial cleft cyst. Mayo Clinic
  3. [3]National Library of Medicine. Branchial Cleft Cyst. StatPearls. NIH

Doctor Visit Checklist

Bring this checklist to your next pediatrician visit to discuss My Baby Has a Lump on the Side of Their Neck (Branchial Cleft Cyst).

Things to mention

  • Describe when you first noticed has a lump on the side of their neck (branchial cleft cyst) and how it has changed over time.
  • Note your baby's current age and which age-specific patterns you are seeing.
  • Mention if you notice a new lump on the side of your baby's neck.
  • Mention if a known branchial cleft cyst seems to be growing.
  • Let your doctor know if you have noticed any related concerns, such as changes in feeding, sleep, or movement patterns.
  • Bring a list of any questions or observations you want to discuss at the appointment.

Observations to share

  • You notice a new lump on the side of your baby's neck
  • A known branchial cleft cyst seems to be growing
  • There is intermittent drainage from a small opening on the neck

Urgent signs to report immediately

  • The cyst becomes rapidly swollen, red, warm, and painful (infected cyst requiring antibiotics)
  • A neck mass is hard, rapidly growing, or accompanied by other concerning symptoms

My notes

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Bottom line

Most cases of has a lump on the side of their neck (branchial cleft cyst) are normal. Talk to your pediatrician if the cyst becomes rapidly swollen, red, warm, and painful (infected cyst requiring antibiotics).

Trust your instincts. If something feels wrong, reach out to your pediatrician. Worrying about your baby means you care — that is a good thing.

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My Baby Has a Lump in the Middle of Their Neck (Thyroglossal Duct Cyst)

A thyroglossal duct cyst is the most common congenital midline neck mass in children. It appears as a painless, round lump in the middle of the neck, usually near or below the hyoid bone (the bone you can feel at the base of the tongue area). It characteristically moves upward when the child swallows or sticks out their tongue. While usually harmless, surgical removal is recommended because these cysts can become infected.

My Baby Has Swollen Lymph Nodes in Their Neck

Swollen neck lymph nodes (cervical lymphadenopathy) are extremely common in babies and young children and are almost always caused by routine infections like colds, ear infections, or throat infections. Neck nodes up to 1 cm are generally considered normal in children. They may enlarge during infections and take weeks to return to normal size. Most are harmless, but nodes that are very large, hard, fixed, or associated with other concerning symptoms need evaluation.

When Should My Baby See a Pediatric ENT?

A pediatric ENT (otolaryngologist) specializes in ear, nose, and throat conditions in children. Common reasons for referral include recurrent ear infections (3+ in 6 months or 4+ in a year), hearing loss, chronic ear fluid, enlarged tonsils or adenoids causing sleep or breathing problems, stridor, chronic sinusitis, airway abnormalities, and neck masses. These specialists can perform ear tube surgery, tonsillectomy, adenoidectomy, and airway evaluations.

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