Keywords
synovial chondromatosis/diagnostic imaging - synovial chondromatosis/surgery - synovial
chondromatosis/diagnosis - synovial chondromatosis/pathology - synovitis
Introduction
Synovial chondromatosis is a rare condition characterized by benign chondrogenic metaplasia
of extra-articular synovial tissue.[1] Transformation of the synovium leads to the formation of cartilage bodies that may
reside within the synovium itself or become free-floating within the tendon sheath.
The disease is most frequently reported in individuals in their third to fifth decades
of life, with a slight predilection for males.[2]
Synovial chondromatosis is typically a localized disease, affecting a single tendon
sheath of the hand or foot. Invasion of multiple adjacent structures has been previously
reported, but it is exceedingly rare.[3] The presence of a palpable mass is often the presenting initial complaint since
this condition generally presents without pain or restricted range of motion. The
cartilage bodies normally ossify, resulting in an obvious radiographic appearance.
In cases where they do not ossify, magnetic resonance imaging (MRI) or computed tomography
(CT) scans can help in the diagnosis.[2]
We present a case of extensive synovial chondromatosis of the flexor hallucis longus
(FHL), flexor digitorum longus (FDL), posterior tibialis (PT), and plantar tarsal
region in a 48-year-old male.
Objectives
To report a rare case of a patient with extensive synovial chondromatosis affecting
all flexor tendons in the tarsal tunnel, its radiological features, surgical treatment
and clinical outcome.
Case Report
A 48-year-old male presented with six to eight weeks of plantar heel pain involving
the right foot. On initial inspection, the skin overlying the right foot and ankle
was intact with minimal swelling, and a 4 cm posteromedial mass with irregular borders
was noted in the ankle ([Fig. 1]). The patient indicated that this mass had been slowly enlarging for the past six
years. Further examination revealed decreased sensation over the medial heel and plantar
aspect of the foot, tenderness plantarly in the insertion of the plantar fascia, and
a positive Tinel Sign over the tarsal tunnel. Ankle and subtalar range of motion were
within normal limits. Radiographs of the right foot and ankle showed plantar osteophytes
and a Haglund's lesion, but no calcification was evident within the mass ([Fig. 2]). T2 MRI demonstrated a 4 cm irregular mass compressing the neurovascular bundle.
There was extensive involvement of the FDL, FHL, and PT tendon sheaths in the posteromedial
ankle with extension through the plantar tarsal region ([Fig. 3]). At the time of diagnosis, the patient opted for conservative treatment with a
boot, NSAIDs, and physical therapy. However, the patient returned for follow-up 10
weeks later complaining of the same symptoms.
Fig. 1 Large irregular mass visible over posterior medial maleolus.
Fig. 2 (A) Standing anteroposterior; (B) lateral radiographs of right ankle demonstrating
no evidence of calcification within the mass.
Fig. 3 (A) Coronal T2 MRI image of the right ankle showing high intensity signal representing
posteromedial mass; (B) axial T1 MRI image of the right ankle showing low intensity
signal of mass with involvement of the flexor hallucis longus, flexor digitorum longus,
and posterior tibialis tendon; (C) sagittal T1 MRI image of the right ankle showing
posteromedial involvement with extention into the plantar tarsal region.
After exhausting conservative management options, the patient underwent surgical excision
of the tumor. Intraoperatively, the mass was found to involve the tendon sheath covering
the FHL, FDL and PT tendons ([Fig. 4]). Tarsal tunnel release and gastrocnemius recession were also performed. Histopathological
evaluation of the mass demonstrated clusters of clonal chondrocytes arranged in lobules,
with variable atypia and occasional binucleation, confirming the diagnosis of synovial
chondromatosis ([Fig. 5]). The patient's post-operative course was uncomplicated. By his 8-week postoperative
clinic visit, the patient's pain and tarsal tunnel symptoms had completely resolved.
Fig. 4 (A) Intra-operative image demonstrating extensive tendon involvement of mass; (B)
gross pathologic specimen.
Fig. 5 Transverse histological sections of the synovial chondromatosis specimen showing
clusters of chondrocytes and varying degrees of atypia.
We have informed the patient that the data concerning this case would be submitted
for publication, and they have consented it (IRB approval 6/29/2016 under number X160503004).
Discussion
Synovial chondromatosis is a rare condition,[1] typically found as an isolated lesion affecting a single tendon sheath in the hand
or foot. It is exceedingly rare for the disease to have multifocal involvement and
be located in the ankle region. Radiographs show a soft tissue mass and calcifications
90% of time, while CT demonstrates calcification in 100% of tenosynovial chondromatosis.[2] MRI is especially useful in diagnosis as well, as it is able to reveal intrinsic
characteristics of chondroid tissue and provide further insight into the precise locations
of lesions.
The differential diagnosis for synovial chondromatosis is dependent upon the aforementioned
imaging modalities used to assess the condition. A radiograph revealing ossified loose
bodies and bizarre parosteal osteochondramotus proliferation should raise concern
for giant cell tumor of the ankle, chondrosarcoma, or synovial sarcoma. Conversely,
if radiographs do not show ossified loose bodies but reveal soft-tissue distension
of a tendon sheath, then differential considerations should include tenosynovitis,
tenosynovial chondromatosis, and tenosynovial giant cell tumor. MRI allows for enhanced
soft-tissue detail and aids in precise localization of lesions in relation to the
tendon sheath. A fluid-distended tendon sheath filled with innumerable small loose
bodies on MRI should lead to the consideration of synovial chondromatosis, juvenile
idiopathic arthritis (JIA), or rheumatoid arthritis (RA), which commonly presents
with rice bodies. Intravenous gadolinium can be useful in discerning inflammatory
changes, as seen in JIA or infection. In our case, MRI showed an irregular mass involving
the tendon sheath of the FHL, FDL, and PT which extended through the plantar tarsal
region. Taking into account radiographic and MRI results, the diagnosis in this case
was determined to be tenosynovial chondromatosis.
To our knowledge, there have only been four previously reported cases of synovial
chondromatosis involving the FHL tendon sheath,[4]
[5]
[6]
[7] and only 1 of these cases involved the triad of the FHL, FDL, and tarsal tunnel.[4] In the case in which the FHL, FDL, and tarsal tunnel were all affected, a 23-year-old
man experienced occasional pain at the site for 13 years.[4] His initial diagnosis was made based upon multiple ossified bodies seen on radiographs.
In our case, the extensive involvement of the FHL, FDL, PT, and tarsal tunnel combined
with the large size of the tumor demonstrate the extensive growth that can occur before
the patient becomes symptomatic. Even when the tumor does reach a critically large
size, associated symptoms are typically minor. Tenderness is not uncommon but restriction
of ankle motion is generally not observed. As a result, it is critical that physicians
become familiar with the relatively indolent presentation of this condition and the
wide variety of imaging findings that may be present. Surgical resection is the mainstay
therapy; however, tenosynovial chondromatosis has a high recurrence rate. Therefore,
close follow-up is critical after surgical treatment.
We report a case of extensive synovial chondromatosis involving all flexor tendons
in the tarsal tunnel that was correctly diagnosed by clinical and imaging findings
and required early surgical resection to avoid long-term neurovascular complications.
