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PubMed This is a summary of 9 peer-reviewed journal articles Updated
Pediatrics · Congenital pseudarthrosis of the clavicle

Signs, Symptoms, and Look-Alikes

At a Glance

The most common sign of congenital pseudarthrosis of the clavicle (CPC) is a painless lump on the right collarbone at birth. Unlike a birth fracture, an X-ray of CPC shows smooth bone ends without any new bone healing (callus formation), and the child retains full use of their arm.

When a child is diagnosed with congenital pseudarthrosis of the clavicle (CPC), the most common sign is a visible, painless lump over the collarbone that is noticed shortly after birth [1]. Because this lump involves a bone, it is often mistaken for other conditions. Understanding how doctors distinguish CPC from its “look-alikes” can provide peace of mind.

Common Signs and Presentation

In the vast majority of cases, CPC follows a very specific pattern:

  • The “Painless Bump”: Unlike a broken bone, the lump in CPC does not cause the child pain when touched or when the arm is moved [1][2].
  • Location: It almost always occurs on the right side (about 95% of the time) [2]. In rare cases, it can affect both sides (bilateral), which requires doctors to look closely to rule out other syndromes [3].
  • Appearance: The lump may become more prominent as the child grows and loses “baby fat,” but the child typically maintains a full range of motion in their shoulder [2][1].

How Doctors Rule Out a Birth Fracture

It is very common for CPC to be initially misdiagnosed as a clavicle fracture (broken collarbone) sustained during a difficult delivery. Doctors use X-rays to tell the difference:

  1. Callus Formation: When a bone breaks, the body immediately begins building a bridge of new bone called a callus. In CPC, there is no callus formation because the bone never truly “broke”—it simply didn’t fuse during development [3][4].
  2. Bone Ends: In CPC, the ends of the two bone segments often appear smooth and rounded (atrophic) on an X-ray, rather than the sharp, jagged edges seen in a fresh fracture [2].

Distinguishing CPC from Systemic Syndromes

Doctors also look for signs that the clavicle issue might be part of a larger, systemic condition. CPC is an isolated anomaly, meaning it usually happens on its own without affecting other parts of the body.

  • Cleidocranial Dysplasia (CCD): This is a genetic condition that also affects the collarbones. However, children with CCD usually have symptoms on both sides (bilateral) and other signs, such as a large “soft spot” (fontanelle) on the head that stays open longer than usual, and dental issues [5][2].
  • Neurofibromatosis Type 1 (NF1): While NF1 can involve bone thinning and “false joints” (pseudarthrosis), it usually affects the lower leg (tibia). It is also accompanied by specific skin findings, such as “cafe-au-lait” spots (light brown birthmarks) [2][4].

Rare Complications: Thoracic Outlet Syndrome

While most children with CPC have no symptoms other than the lump, a very small number may develop Thoracic Outlet Syndrome (TOS) as they get older. This happens if the “false joint” or the surrounding tissue begins to press on the nerves (brachial plexus) or blood vessels (subclavian artery) that pass under the collarbone [6][7].

Symptoms to watch for (rare):

  • Numbness or a “pins and needles” sensation in the arm or hand [8].
  • The hand on the affected side feeling noticeably cooler or looking paler than the other hand [6].
  • Weakness in the grip or arm strength.

If these symptoms appear, doctors may recommend surgery to stabilize the bone and relieve the pressure [6][9].

Navigate:

Common questions in this guide

How do doctors tell the difference between CPC and a broken collarbone from birth?
Doctors use X-rays to look at the bone ends and check for healing. A broken collarbone will show new bone growth called a callus, while CPC will show smooth, rounded bone ends with no callus formation because the bone never actually broke.
Is a lump on a baby's collarbone always a sign of a larger genetic syndrome?
While conditions like cleidocranial dysplasia or neurofibromatosis can affect the collarbones, CPC is typically an isolated anomaly. Doctors can confirm this by checking for other signs, such as an open soft spot on the head, dental issues, or specific skin birthmarks.
Can CPC cause nerve problems or pain in the arm later in life?
In most cases, the lump does not cause pain or restrict movement. However, in rare instances as the child grows, it can press on nearby nerves or blood vessels, causing a condition called Thoracic Outlet Syndrome. Symptoms to watch for include numbness, weakness, or a pale, cool hand on the affected side.
Will my child have limited arm movement because of the collarbone lump?
No, children with this condition typically maintain a full, normal range of motion in their affected shoulder and arm, despite the visible lump on their collarbone.

Questions to Ask Your Doctor

Curated prompts to bring to your next appointment.

  1. 1.On the X-ray, do the bone ends appear rounded or pointed, and is there any evidence of callus formation?
  2. 2.How can we be certain this is an isolated issue and not part of a condition like cleidocranial dysplasia or neurofibromatosis?
  3. 3.Are there specific physical signs in my child's head shape or dental development that you are checking to rule out other syndromes?
  4. 4.At what point would we need to worry about the lump pressing on nerves or blood vessels?
  5. 5.Are there any signs of arm weakness or circulatory changes I should look for at home as my child gets older?

Questions For You

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References

References (9)
  1. 1

    Congenital Pseudarthrosis of the Clavicle: A Case Report and a Hypothesis for the Right-Side Predominance.

    Al-Abdi SY, Khalil AM, Elnamky AN, Sherif KE

    Cureus 2022; (14(9)):e29157 doi:10.7759/cureus.29157.

    PMID: 36259035
  2. 2

    [When to think about pediatric congenital pseudoarthrosis of the clavicle? Presentation of 2 cases].

    Justich Zabala PR, Giniger Vidal RP, Rubio Pérez MJ, et al.

    Archivos argentinos de pediatria 2020; (118(2)):e194-e198 doi:10.5546/aap.2020.e194.

    PMID: 32199064
  3. 3

    A Case of Bilateral Congenital Pseudoarthrosis of Clavicle: An Uncommon Variant of a Rare Disorder.

    Boeisa AN, Alshammary AA, Albunyan S, et al.

    Cureus 2024; (16(8)):e66594 doi:10.7759/cureus.66594.

    PMID: 39252736
  4. 4

    Congenital Clavicular Pseudoarthosis-How to Differentiate It From the More Common Clavicular Fractures.

    Chalfant JS, Sanchez TR

    Pediatric emergency care 2019; (35(2)):e37-e39 doi:10.1097/PEC.0000000000001118.

    PMID: 28463941
  5. 5

    Cleidocranial Dysplasia: A Rare Case Report.

    Dhobley AA, Thombre AV, Ghatage D, Patil RI

    Journal of pharmacy & bioallied sciences 2023; (15(Suppl 2)):S1335-S1337 doi:10.4103/jpbs.jpbs_212_23.

    PMID: 37693969
  6. 6

    Thoracic Outlet Syndrome Secondary to Vascular Insufficiency from Congenital Pseudarthrosis of the Clavicle: A Case Report.

    Hysong AA, Denduluri SK, Arko FR, et al.

    JBJS case connector 2023; (13(2)) doi:10.2106/JBJS.CC.22.00426.

    PMID: 37279298
  7. 7

    Late presentation of critical upper limb ischemia caused by pseudarthrosis of the clavicle.

    Miyamotto M, Sanvido LV, Brendolan LF, et al.

    Jornal vascular brasileiro 2018; (17(2)):174-177 doi:10.1590/1677-5449.009617.

    PMID: 30377431
  8. 8

    Brachial Plexus Functional Outcomes After Thoracic Outlet Surgery as Measured by the Validated Brachial Assessment Tool.

    Ferris S, Hill B, Xie Y

    ANZ journal of surgery 2025; (95(10)):2178-2184 doi:10.1111/ans.70202.

    PMID: 40444693
  9. 9

    Neurogenic Thoracic Outlet Syndrome: A Current Literature Review.

    Attaar N, Pascarella L

    The American surgeon 2025; (91(12)):2164-2172 doi:10.1177/00031348251358432.

    PMID: 40626394

This page provides informational content about CPC symptoms and look-alike conditions. Always consult a pediatric orthopedic specialist for an accurate diagnosis and evaluation of any collarbone lump.

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