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Journal of Medical Case Reports
Capsular synovial metaplasia mimicking silicone leak of a breast
prosthesis: a case report
Sarah Krishnanandan1, Ali Abbassian*2, Anup K Sharma3 and Giles Cunnick4
Address: 1SpR in Accidents and Emergency, Kingston Hospital, Kingston, Surrey, KT2 7QB, UK, 2SpR in Trauma and Orthopaedics, Mayday
University Hospital, Croydon, CR7 7YE, UK, 3Department of Breast Surgery, St. George's Hospital, Tooting, London, SW17, UK and 4Wycombe
General Hospital, Queen Alexandra Road, High Wycombe, Bucks, HP11 2TT, UK
Email: Sarah Krishnanandan - email@example.com; Ali Abbassian* - firstname.lastname@example.org;
Anup K Sharma - email@example.com; Giles Cunnick - firstname.lastname@example.org
* Corresponding author
Introduction: Synovial metaplasia around a prosthesis and in particular around silicone breast
implants has been noted by various investigators, but has unknown clinical significance. We report
on a patient where a large amount of synovial fluid mimicked rupture of an implant. We believe this
to be an unusual clinical presentation of this phenomenon. Review of the English language literature
failed to identify a comparable case.
Case presentation: A 25-year-old woman had undergone bilateral breast augmentation for
cosmetic reasons. One implant was subsequently subjected to two attempts at expansion to
correct asymmetry. The patient was later found to have a large quantity of viscous fluid around the
port of that same prosthesis. Histological assessment of the implant had consequently confirmed
capsular synovial metaplasia. This had initially caused the suspicion of a silicone 'bleed' from the
implant and had resulted in an unnecessary explantation.
Conclusion: Capsular synovial metaplasia should be ruled out before the removal of breast
implants where a leak is suspected. Manipulation and expansion of an implant may be risk factors
for the development of synovial metaplasia.
Synovial metaplasia around prostheses is regarded as a
transitional phenomenon . We describe the case of a
patient in whom, at the time of removal of a prosthetic
port, the quantity of viscous fluid produced as a result of
metaplasia caused us to suspect that a silicone bleed had
occurred. This resulted in what later appeared to have
been the unnecessary explantation of her implant.
A fit and healthy 25-year-old Caucasian woman presented
with asymmetry and gross bilateral tubular deformity of
the breasts. Subsequently, a bilateral breast reconstruction
with 350 cc Becker™ (Mentor, UK) implants was per-
formed. At the time of surgery, 200 ml of saline was used
to inflate both implants. The left implant was further
inflated 1 and 5 months later using 80 ml of normal saline
on both occasions, to optimize symmetry.
Published: 15 August 2008
Journal of Medical Case Reports 2008, 2:277doi:10.1186/1752-1947-2-277
Received: 23 January 2008
Accepted: 15 August 2008
This article is available from: http://www.jmedicalcasereports.com/content/2/1/277
© 2008 Krishnanandan et al; licensee BioMed Central Ltd.
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0),
which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Journal of Medical Case Reports 2008, 2:277http://www.jmedicalcasereports.com/content/2/1/277
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One year later, both ports were removed as a day case pro-
cedure. At that time, the right port was removed without
complication. However, the left port was surrounded by a
viscous fluid simulating implant rupture. A silicone gel
bleed was suspected and another operation was planned
where the left prosthesis was replaced with another per-
manent implant. The fluid and a sample of the peripros-
thetic capsule were sent for histological review.
Histological examination revealed that the fluid was syn-
ovial fluid. The sample of capsule was found to be
fibroadipose tissue, composed of fibrin-organizing histio-
cytes, lymphocytes and multinucleate giant cells. The cap-
sule had undergone synovial metaplasia, which explained
the presence of synovial fluid around the left implant. A
typical histological appearance of synovial metaplasia is
shown in Figure 1.
Synovial metaplasia was first described by Brody and
White  following their studies on implanted silicone
joints in chickens. Another study of 85 patients with
breast prostheses showed that the incidence of synovial
metaplasia was 40% and that this condition was not as
rare as had been previously suspected .
A number of theories have been suggested to explain this
phenomenon. One study suggested that the tissue reac-
tion was a response to implants with a textured surface
rather than a smooth surface . In contrast, Ko et al. 
suggested that the occurrence of synovial metaplasia did
not correlate with the implant type. Instead they postu-
lated that implant age may be a significant factor. The inci-
dence had been shown to decrease with the age of the
implant, suggesting that it may be a transitional finding in
capsular maturation. This is in contrast to one report of
synovial metaplasia that had presented with breast firm-
ness and pain 26 years following implantation .
Another hypothesis suggests that mechanical stress may
influence the development of synovial metaplasia. In one
study , the bone-cement interface of loose hip prosthe-
ses, which is under considerable mechanical stress, was
shown to undergo synovial metaplasia. Mechanical inter-
ference has also been associated with its development in
the skin . Mechanical stress may influence the develop-
ment of synovial metaplasia in breast implants because of
repeated surgery, expansion of the implants, the pendu-
lous movement of the breasts or with chest wall muscle
activity. Synovial metaplasia secretes lubricating factors
and this may be beneficial for the reduction of capsular
contracture. In one report, synovial metaplasia occurred
after multiple manipulations and tissue expansions .
The investigators believed that this played an important
role in the development of the metaplasia. The mechani-
cal interference theory may explain the findings in our
patient. The left prosthesis was expanded on two occa-
sions, whereas the right prosthesis was not expanded at
all. Synovial fluid was only macroscopically evident on
the left side.
Silicone breast implants that are suspected of a leak
should be assessed by histological examination of the
fluid to rule out synovial metaplasia. This is particularly
important if the implant has been subjected to expansions
or manipulations. The clinical significance of synovial
metaplasia is uncertain, however, increased awareness of
this phenomenon by surgeons may reduce the unneces-
sary explantation of perfectly intact prostheses. If a leak is
found to be due to synovial metaplasia, a period of obser-
vation and delay in explantation is advised as this may
well be a transitional phenomenon.
Consent could not be obtained as the patient was untrace-
able. However, we believe the article contains a worth-
while clinical lesson which could not be made as
effectively in any other way. The risk of identification of
the patient is minimized by measures designed to prevent
the identity of the patient being revealed either to others
Capsular synovial metaplasia
Capsular synovial metaplasia. Sections from the cavity
show the surface of the capsule lined by fibrohistiocytic cells.
The nuclei of these cells are basally oriented and are polar-
ized perpendicular to the cavity surface. The interface
between the capsule and implant space is smooth. The over-
all features are indicative of synovial metaplasia.
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Journal of Medical Case Reports 2008, 2:277 http://www.jmedicalcasereports.com/content/2/1/277
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or to the patient's relatives. We expect the patient and their
next of kin would not object to the publication of this
The authors declare that they have no competing interests.
SK and AA were involved in the literature search, writing
up of the case and preparing the revision. AS and GC man-
aged the clinical care of the patient as well as assisting in
writing the manuscript.
We acknowledge the help and expertise of the histopathology department
at St. George's Hospital and in particular Dr V. Thomas for the diagnosis
and preparation of histological slides.
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