Abstract
Tenosynovial giant cell tumors (TGCT), are benign proliferative lesions arising from the tendon sheaths, synovium, or bursae. They commonly occur in the extremities and may present as localized or diffuse forms. Although well described in the hand, involvement of the foot and ankle is less frequently reported and may clinically resemble chronic tendinopathy or soft tissue inflammation, which may contribute to delayed diagnosis.
We present a 64-year-old male with a 14-year history of progressive posterior ankle pain refractory to conservative treatment. Physical examination demonstrated focal tenderness and restricted motion along the flexor hallucis longus (FHL) tendon. Radiographs were unremarkable. Magnetic resonance imaging identified a lobulated 2.5 × 2.5 × 1.2 cm mass within the distal FHL muscle–tendon unit and a second lesion along the Achilles peritenon consistent with chronic hematoma.
Both lesions were surgically excised through a posterior approach. Histopathologic analysis confirmed a localized tenosynovial giant cell tumor involving the FHL tendon and an organized hematoma adjacent to the Achilles tendon. The patient reported symptomatic improvement following resection.
This case demonstrates that persistent ankle pain attributed to tendonitis may represent underlying soft tissue tumors and supports the use of advanced imaging when symptoms fail to resolve following conservative management. Surgical excision with histologic evaluation remains the standard treatment for localized TGCT and allows for definitive diagnosis while reducing recurrence risk.
Introduction
Giant cell tumors (GCT) are one of the most frequently occurring soft tissue tumors of the lower extremity. Tenosynovial giant cell tumor (TGCT) are benign tumors with locally aggressive proliferation of the synovium and are most often diagnosed in the third and fourth decade of life. These tumors can be classified as localized or diffuse with the diffuse classification having the potential to metastasize, resulting in an important workup when considering treatment of any unusual soft tissue mass. This is especially important when considering metastasis occurs 3–4 % of the time with patients who have GCT. We present a case of a giant cell tumor involving the flexor hallucis longus (FHL) tendon.
Case report
A 64 year old male with a history of bilateral achilles tendon tear presented to the podiatry clinic for left ankle pain for a 14 year duration. He has an antalgic gait and notes feeling tightness to the posterior medial aspect of his left ankle. He attempted physical therapy, NSAID, and heel lifts, but his pain continued to worsen.
On physical exam, he had pain along the course of the FHL tendon with plantarflexion of the hallux along with restricted movements along the FHL tendon course. Ankle range of motion was within normal limits with a negative Silverskoid. There was also a healed cicatrix to the Achilles tendon and a positive tendon bulge along the Achilles tendon. On the radiograph, there was no osseous abnormality appreciated. On MRI there was a Lobular mass noted to the distal aspect of the FHL muscle measuring 2.5 × 2.5 × 1.2 cm. Additionally, there was a crescentic signal abnormality from the posterior Achilles peritenon, likely reflecting chronic hematoma, measuring 3.1 × 1.6 × 0.5 cm. Given the patient’s worsening pain despite conservative treatment the decision was made to surgically excise these lesions.
Operative procedure
A 4 cm linear longitudinal incision was made just lateral to the Achilles tendon bulge. Sharp and blunt dissection was performed through the soft tissue to the level of peritenon. The incision was then deepened through the peritenon which was then reflected medially and laterally, revealing the suspected chronic hematoma seen on MRI. This mass was carefully excised in toto, passed off the surgical field, and sent to pathology. Next, the Achilles tendon was retracted medially and blunt dissection was performed until the mass within the myotendinous junction of the FHL was identified. This mass was carefully excised in two, passed off the field and sent to pathology.
Discussion
Tenosynovial giant cell tumors are separated into two categories: localized tenosynovial giant cell tumor (L-TGCT) and diffuse tenosynovial giant cell tumor (D-TGCT). Multiple studies state that GCTs are common in the third to fifth decade of a patient’s lifetime. A systematic review by Lenze et al. reported multiple treatments for GCT, including radiotherapy, open surgical resection, and arthroscopic resection.
One reported case of a giant cell tumor on the tendon was identified in the hand. In this case, there was a multi-lobulated lesion surrounded by a pseudocapsule at the volar aspect of the ring finger. Excision of the mass was performed with no recurrence after 5 years. When evaluating for giant cell tumors, osseous involvement is approximately 33 %.
When concerning malignancy, there are reports of approximately 1–9 % regardings GCT. When these lesions metastasize it is commonly spread into the lungs. Howard et al. reported histologically the difference between a benign and malignant GCT. Histologically, nodular infiltrates of cells with large nuclei characterized as atypical mitosis is a feature of malignant GCT. Opposed to this case pathology, the lesion was well demarcated and nodular. There was low concern for infiltrate past the tenosynovial sheath.
Complete resection of the GCT, benign or malignant, appears to be the standard of practice for these soft tissue tumors. Radiotherapy was reported to have an 80 % success rate in the treatment of tenosynovial GCT. Hinikier et al. stated that 100 % of patients receiving salvage therapy are disease-free.
Rare cases are known regarding flexor hallucis longus GCT tenosynovitis. A case on peroneus brevis GCT explained the importance of preserving tendon strength after resection of the mass. Local destruction of the tendon may lead to an inflammatory response. This inflammatory response may lead to avascularization of the tendon, making it prone to rupture.
Complications of excision of a giant cell mass depend on the extent of the excision and the location of the mass. Marginal en bloc resection may lead to risk of rupture of the tendon, wound dehiscence, and nerve damage. Local recurrence in certain populations is 19.7 % for ankle lesions and 12.5 % in foot lesions. Other studies found recurrences of <10 % in foot lesions.
This case report is subject to inherent limitations, including limited external validity and selection bias. The outcomes of this single case may not be generalizable to all patients, and results should be interpreted in the context of descriptive clinical experience.
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