Morel-Lavallée Lesion in Children

The subcutaneous space is a vast region of potential space where things can collect.  Sometimes this can be used to our advantage, like when we need to give subcutaneous fluids to a dehydrated patient without an IV, or when we need to give SQ medications for things like Sulfonylurea overdose, Hereditary Angioedema, or DVTs . Sometimes, however, these deeper layers of the subcutaneous space can collect dangerous infections, like Necrotizing Fasciitis. And sometimes the subcutaneous layers can be a place where blood collects after an injury, whether from birth like a Neonatal Subgaleal Hemorrhage, or from Hair Braiding.  Let’s talk about another injury that can cause a subcutaneous collection of blood from a shearing injury – a Morel-Lavallée lesion. Although this is a rare diagnosis, there are plenty of teenagers who are at risk of this injury, and we must stay vigilant for its presence.

Morel-Lavallée Lesion – Basics

  • Closed/internal degloving injury of the soft tissue, typically from high energy trauma [Scolaro 2016]
    • First described by French physician Victor-Auguste-François Morel-Lavallée in 1863 [Morel-Lavellée 1863, Scolaro 2016]
    • Most common areas are hip, thigh, and pelvic region [See Figure 2 of Scolaro 2016 [Vanhegan 2012, Scolaro 2016, Singh 2018]
  • Results from high energy shearing force [See Figure 1 from Scolaro 2016 and/or this image].
  • Separates the hypodermis and subdermal fat from the underlying fascia in 4 stages [Scolaro 2016, Singh 2018, Sharareh 2021, Seah 2022]
    • Dermis separates from underlying fascia, disruption of the perforating vascular and lymphatic structuresBlood, lymph, and fatty debris collects from leakage from subdermal plexus, drains in between the tissue planes
    • Components replaced by serosanguinous fluid
    • Metabolic and inflammatory products in these fluids cause continued leakage 

Morel-Lavallée Lesion – Presentation

  • May initially be missed in a polytrauma patient due to distracting injuries [Scolaro 2016, Singh 2018]
    • Up to 1/3 may go undiagnosed acutely [Hudson 1996, Singh 2018]Up to 25% caused by motor vehicle collisions [Nickerson 2014, Singh 2018] Increasing recognition of this being caused by sports injuries [Vanhegan 2012, Singh 2018]
    • Up to 8% with concurrent acetabulum fractures [Sharareh 2021]
  • Presents either acutely or subacutely days after an injury [Scolaro 2016]
    • Size of vascular and lymphatic disruption, rate of fluid accumulation, and patient body habitus impact rapidity of identification [Scolaro 2016, Singh 2018]
  • Clinically may show ecchymosis, swelling, fluctuance, or skin hypermobility. [Scolaro 2016, Singh 2018]
    • Discoloration of the skin may be delayed by days
  • Common locations [Vanhegan 2012, Scolaro 2016, Singh 2018, Seah 2022]
    • greater trochanter/hip (30.4%), 
    • thigh (20.1%), 
    • pelvis (18.6%),
    • knee (15.7%), 
    • gluteal region (6.4%), 
    • lumbosacral area (3.4%), 
    • abdominal area (1.4%), c
    • alf/lower leg (1.5%), 
    • and head (0.5%)

Morel-Lavallée Lesion – Diagnosis

  • Ideally (but uncommonly) this is picked up on clinical examination [Vanhegan 2012, Scolaro 2016]
  • More commonly CT or MRI picks up both small and large lesions
    • MRI is more sensitive for diagnosis and characterization [Scolaro 2016, Singh 2018] [See Figure 3 of Scolaro 2016]
  • Ultrasound can be helpful to show lesion superficial to muscle fascia and demonstrate no flow and compressibility [Singh 2018]
  • Average lesion size is 30cm x 12 cm [Tseng 2006]
  • Six lesion patterns based on lesion age and MRI imaging [Mellado 2005, Scolaro 2016, Singh 2018, Seah 2022]
    • Type 1- simple seroma
    • Type 2- subacute hematoma
    • Type 3- mature organized hematoma 
    • Type 4- closed fatty laceration complicated by perifascial dissection
    • Type 5- perifascial nodular lesion
    • Type 6- infected lesion with sinus tract, septations, and capsular formation
  • Differential diagnosis includes post operative seroma, simple hematoma, bursitis, fat necrosis, hemangioma, soft tissue sarcoma, early myositis ossificans [Vanhegan 2012, Singh 2018]

Morel-Lavallée Lesion- Treatment

  • Management depends on the size, location, and age of injury [Vanhegan 2012, Nickerson 2014, Scolaro 2016, Singh 2018]
    • Close observation with, compression banding 
    • Percutaneous Drainage
      • Smaller incisions with copious irrigation and aspiration then compression banding or percutaneous drain can be used [Hudson 1992, Tseng 2006]
    • Open debridement and irrigation [Vanhegan 2012, Scolaro 2016]
      • Done early to remove material that can become colonized by bacteria and infected [Scolaro 2016]
      • Could compromise subdermal vascular plexus
      • Best for larger, >50 mL fluid collections [Singh 2018]
    • Alternatives: serial aspiration, compression banding, liposuction, sclerosis agents (talc, doxycycline) have been used to limit additional soft tissue injury [Vanhegan 2012, Scolaro 2016, Singh 2018]
    • A quilting procedure was described by Vanhegan for treatment of a chronic recurrence [Vanhegan 2012]
  • There are no prospective large studies to compare open treatment vs less invasive treatment [Scolaro 2016]
    • A systematic review and some retrospective studies indicated less recurrence with open treatment versus percutaneous or nonsurgical treatment, especially if >50 mL initial collection. [Shen 2013, Nickerson 2014, Scolaro 2016]
    • Singh et al proposed an algorithm to guide treatment. [Singh 2018 Figure 1]

Morel-Lavallée Lesion- Complications

  • Recurrence is most common complication [Sharareh 2021]
  • Pressure necrosis of overlying skin leading to skin breakdown [Singh 2018]
  • Bacterial colonization of the soft-tissue injury (up to 46% of sampled lesions) can lead to high rates of perioperative infection [Scolaro 2016, Singh 2018]
  • Pseudocyst formation or cosmetic deformity can also result if there is delayed diagnosis or untimely management [Scolaro 2016]
  • Infection or necrosis of the soft tissue envelope if improper or delayed diagnosis [Scolaro 2016]

Moral of the Morsel

  • High forces can do bad things! Morel-Lavallée degloving lesions are related to high velocity shearing injuries.
  • Hard to say and hard to see. A degloving injury doesn’t sound like it should be difficult to detect… but, it can be! Remain vigilant for this sneaky condition as early identification can prevent long term morbidity, infection, and cosmetic problems.
  • Big fluid needs big procedures. Surgical treatment is best for large >50 mL collections.
  • Bad enough to cause an internal degloving injury… likely bad enough to cause other injuries too. Be vigilant of concurrent and underlying injuries that are easily missed in polytrauma patients.


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Christyn Magill
Christyn Magill
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