Clin Case Rep. 2019;7:597–598.
A 43‐year‐old male presented with painful bilateral chest
lesions started a few months prior. The lesions were located
anterior lower chest and painful during surfing. While his
medical and family histories were unremarkable, his personal
history revealed that he was a surfer with 20 years’ of expe-
rience. Neither palpation nor CT images (Figure 1), which
showed soft tissue density with ill‐defined margin, reached
the diagnosis. T2‐weighted and T1‐weighted MR imaging
(Figure 2) showed the lesions with heterogeneous low signal
intensity, with fibrous‐rich component especially with T2‐
weighted imaging. These MR imaging findings along with
the history of frequent surfing gave out the correct diagnosis
of surfer's knots. Surfer's knots are benign acquired fibrotic
connective tissue nodules that develop in response to repet-
itive low‐grade trauma.1 In our case, the patient's chest was
presumably exposed to repetitive contact with a surfboard
during paddling (Figure 3). They are typically seen in tibial
tuberosities, dorsum of the feet, and the chest.1 Most cases
improve by cessation of surfing. Its diagnosis does not re-
quire imaging if the presentation is typical and the clinician is
aware of this condition. The radiological evaluation leads to
the definitive diagnosis and enables us to avoid unnecessary
Received: 15 August 2018
Revised: 29 October 2018
Accepted: 6 December 2018
Surfers' knots in the anterior chest
This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original
work is properly cited.
© 2019 The Authors. Clinical Case Reports published by John Wiley & Sons Ltd.
1Department of Radiology,The Jikei
University School of Medicine, Tokyo,
2Department of Radiology,Tokyo Dental
College Ichikawa General Hospital, Chiba,
3Department of Internal Medicine,Tokyo
Dental College Ichikawa General Hospital,
Akira Baba, Department of Radiology, The
Jikei University School of Medicine, Tokyo,
Key Clinical Message
A history of frequent surfing can be a key finding when a patient comes in with
subcutaneous lesions on bilateral anterior lower chest. MR imaging could lead to the
diagnosis with its characteristic finding for collagenous mass lesions, though most
cases do not require imaging unless with atypical presentation. This enables clini-
cians to avoid unnecessary invasive procedures.
chest, CT, MRI, radiology, surfers' knots
FIGURE 1 Plain CT (A) and contrast‐enhanced CT (B) revealed
soft tissue density mass lesion with ill‐defined margin in subcutaneous
region of bilateral anterior chest (arrows)
BABA et Al.
invasive procedures. Sometimes the lesions remain with in-
fection and/or pain, and may require surgical resection.2 If
resection or detailed pretreatment evaluation is needed, CT
and MR imaging are useful. Pathologically, surfer's knots
are the thickening of reticular dermis as a result of increased
deposition of collagen, which corresponds well with low
intensity on T2‐weighted MR imaging.
The authors thank Ms. Yukiko Ishii for her illustrating
CONFLICT OF INTEREST
AB: drafted the article. All authors participated in critical re-
view and the revision of the articles. All authors gave the
final approval of the article. All authors have accountability
for all aspects of the work.
Akira Baba https://orcid.org/0000-0001-6913-5307
1. Tashima CK. Letter: Surfer's chest knots. JAMA. 1973;226(4):468.
2. McManus LJ, Thomson A, Whan A. The magnetic resonance
appearance of surfers' knots: a case report. Radiol Case Rep.
How to cite this article: Baba A, Okuyama Y,
Yakabe H, Yamazoe S, Kobashi Y, Mogami T.
Surfers' knots in the anterior chest. Clin Case Rep.
FIGURE 2 On T2‐weighted MR imaging (A) and T1‐weighted
imaging (B), the lesion was identified as heterogeneous low signal
intensity mass (arrows)
FIGURE 3 Schematic drawing of the contact points of a surfer's
chest to a surfboard when paddling