This is an interesting paper of a 4 cm posttraumatic pseudolipoma on the back of the neck of an adult man who has participated in “tar barrel rolling” since adolescence. To the best of our knowledge, this is the first case of a pseudolipoma to be reported in the literature in association with tar barreling.
A 37-year-old healthy man known to have a “tar barreler’s hump” in his local community presented to his general practitioner because his hump had become acutely inflamed. The hump has been present for over fifteen years without causing any symptoms. He has participated in “tar barrel rolling”—a family tradition since adolescence. Examination of his back revealed a 4 cm nontender solid soft tissue mass at the posterior aspect of the lower neck in the interscapular region, there was mild erythema of the overlying skin (Figure
4 cm nontender midline soft tissue mass in the interscapular region in a 37-year-old male “tar barreler.”
Ultrasound examination (Toshiba Aplio XG, 7.5 MHz probe) revealed a hyperechoic mass in the subcutaneous tissues of the interscapular region (Figure
Ultrasound examination (longitudinal view) demonstrates a large subcutaneous mass (bounded by white arrows) in the interscapular region with sonographic features consistent with a lipoid mass, that is, elliptical shape, heterogeneity, longest axis parallel to the skin surface, lack of posterior acoustic enhancement or attenuation, and presence of multiple echogenic lines perpendicular to the ultrasound beam.
MRI of the neck demonstrates a subcutaneous mass (white arrows) in the interscapular region isointense to surrounding subcutaneous fat on T1-weighted sequence (Figure
“Tar barreling” is a world famous tradition native to Ottery St Mary, Devon, Southwest England. The tradition dates back to the 17th century, and it is performed annually on the 5th of November (Guy Fawkes Night). Barrels soaked in tar are set ablaze and carried on the back between the shoulders through the streets. Different categories exist for boys, women, and men depending on the size of the barrels. The event culminates at night with men carrying flaming barrels that weigh up to 30 kg. The festival attracts between 15–20,000 visitors annually.
In a few cases, generations of the same family carry these flaming tar barrels annually; men often start “barrel rolling” at a very young age similar to the case presented. Allegedly, there are a few participating residents in the community who have also developed humps at the back of the neck where these barrels are carried over the years. These humps are known in the local community as “tar barreler’s hump” and are regarded to be of no serious medical significance.
Although there is lack of histological analysis in our case as surgical management was declined, the appearance on ultrasound that is, well-delineated hyperechoic subcutaneous mass with linear echogenic lines perpendicular to the ultrasound, beam and absence of posterior acoustic enhancement or attenuation are typical sonographic appearance of a lipoma or lipoma-like lesion [
PTLs are benign soft tissue tumours that develop in various anatomical regions following acute, chronic or repetitive trauma. The exact pathobiological mechanism of development of PTL is unclear; however various theories via mechanical and inflammatory factors have been postulated. Mechanical factors such as herniation of fatty tissue following traumatic disruption of fascial layers or differentiation of preadipocytes triggered by growth factors and inflammatory mediators such as cytokines released from the preceding haematoma are some of the postulated mechanisms [
Summary table: posttraumatic pseudolipoma (PTL).
Etiology | Sequelae of acute, chronic, or repetitive trauma. Various mechanisms of development are postulated |
Incidence | ~1% |
Gender ratio | F : M = 3.8: 1* |
Age | 18–64 years* |
Risk factors | Acute/chronic/repetitive trauma |
Conservative | |
Treatment | Liposuction |
Surgical excision | |
Prognosis | Unknown. Malignant transformation has never been reported |
Imaging | US—well-delineated hyperechoic subcutaneous mass, no posterior acoustic attenuation or enhancement |
CT—subcutaneous mass with Hounsfield attenuation of fat | |
MRI—homogenous unencapsulated mass isointense to fat on all sequences | |
T1WI-hyperintense (similar to fat) | |
Fat-suppressed sequence—hypointense (similar to fat) | |
Lack of a well-defined low signal intensity fibrous capsule | |
Lack of enhancement following administration of intravenous contrast |
*Based on a review of 124 cases of PTLs by Galea et al. [
Imaging can be used to differentiate benign lipomatous tumours from liposarcomas [
Typical imaging features of PTL, lipoma, and liposarcoma.
US | CT | MRI | |
---|---|---|---|
Posttraumatic pseudolipoma (PTL) | Well-delineated hyperechoic subcutaneous mass | Well-delineated subcutaneous mass with Hounsfield attenuation of fat | Homogenous unencapsulated mass isointense to fat on all sequences |
No posterior acoustic attenuation or enhancement | T1WI-hyperintense | ||
T2WI-hypointense | |||
Fat suppression—hypointense | |||
Absence of a well-defined low signal intensity fibrous capsule | |||
No enhancement following administration of intravenous Gadolinium | |||
| |||
Lipoma | Similar to PTL | Similar to PTL | Signal intensity as PTL |
Usually homogenous | Usually homogenous | ||
May contain thin internal septa (<2 mm) | A well-defined low signal intensity fibrous capsule is usually present | ||
May appear as complex with thick septa (>2 mm) and nonlipomatous components | There may be mild to moderate enhancement following administration of intravenous gadolinium | ||
| |||
Liposarcoma (variable appearance according to histological type according to WHO classification | Heterogeneous, multilobulated usually well-defined fatty mass | Contains large lipomatous and prominent nonlipomatous components such as thick internal septa (>2 mm) | Heterogeneous |
Usually located in the deep soft tissues of the extremities particularly thigh, head and neck, trunk, and retroperitoneum | May contain focal nodules | Moderate to marked enhancement of septa following administration of intravenous gadolinium | |
Calcification or metaplastic ossification may be seen |
We cannot speculate the natural progression of this lesion however malignant transformation into liposarcoma has never been reported as sequelae of PTLs. To the best of our knowledge, this is the first case of PTL in association with tar barrelling to be reported in published the literature.