The etiology of GCTTS has not yet been fully elucidated. Some possible etiologies include disturbances in lipid metabolism, neoplasms, inflammation, trauma, and hemorrhage [13, 14]. However, only two of these etiologies (inflammatory and tumoral) are commonly discussed [15]. Pathologically, GCTTS is composed of synovial mononuclear cells and osteoclast-like multinucleated giant cells [12]. Some physicians and researchers believe that the presence of increased cellularity and the tendency to recur imply neoplastic origin [16, 17]. There are several studies that discuss the importance of genetic factors in the occurrence of GCTTS. De Jong B et al. proved that the existence of trisomy 7 [18] is associated with GCTTS, suggesting the neoplastic aspect in the proliferation [19] of GCTTS (trisomy 7 is associated with a large variety of neoplastic conditions [20]). Similarly, infiltration by histiocytes, macrophages, and plasmatic cells support the possibility of an inflammatory origin [13]. The increased activity of the epidermal growth factor (EGFR) and the growth factor, PDGF, codified by c-erb B oncogenes on chromosome 7, may also contribute to the inflammation caused by synovitis [18,19,20]. We found very few reports [7, 11, 12] of the destruction of tendon as a result of GCTTS. Localized GCTTS commonly occurs in the form of a well-delineated lesion that encircles the tendon instead of infiltrating it. On the contrary, diffuse GCTTS is usually aggressive, occurs as a homogeneous soft-tissue mass and is associated with joint destruction and deterioration [14]. In the limbs, the lesion is contained within anatomically narrow spaces, and can grow along the sheaths causing synovium degeneration and cortical erosion. In the case reported here, the destruction of the extensor indicis proprius tendon was irregular and lacked a well-defined etiology.
While GCTTS is still considered a rare benign clinical disease, it has become more common in recent times. GCTTS can be classified as either localized or diffuse based on its clinical presentation and biological behavior; the latter is known to be more aggressive. In accordance with previously published literature, we diagnosed this case of GCTTS in the wrist as a benign and noninvasive tumor. However, during surgery, we found that the lesion had surrounded, partly infiltrated, and damaged the extensor indicis proprius tendon. Such observations are extremely rare. In this case, the tendon injury seen could not have been iatrogenic because the patient had not received any prior treatments (e.g. surgery, corticosteroid injection). In addition, what’s the possible reasons resulting in the repture of the EIP tendon? We thought that the likely cause of the EIP tendon rupture was combination of GCTTS infiltrating into the tendon and also the mechanical or pressure effect of the EIP tendon excursion under the wrist extensor retinaculum.So decreasing the movement of the left wrist may be helpful to protect the EIP tendon in this case.Intraoperative view, we found that the strength of extensor indicis proprius tendon was satisfactory.We transected part of the affected tendon and sutured longitudinally. Three days after surgery, the patient began functional training and rehabilitation under the guidance of a doctor. The patient recovered well, had no functional impairments, no tendon re-rupture or adhesion, and no recurrence for over 2 years. It is important to closely monitor tendon re-rupture and tumor recurrence. If the tendon re-ruptures or the tumor recurs, tendon repair or radical resection of the tumor must be performed [21]. In addition, patients with tendon re-rupture or tumor recurrence need to undergo tendon repair surgery (either tendon suture or tendon grafting based on the degree of tendon defect) [22].
The clinical presentations and radiological findings of patients may initially indicate the presence and margin of a mass and this may be useful for primary diagnosis, surgical planning and postoperative follow-up.However, the final diagnoses must be made on the basis of the histological examination [23].Sometimes,the final diagnoses were inconsistent with the imaging diagnoses,so a biopsy before the surgery should be recommended.The interval between the onset of the first signs and diagnosis is often long, suggesting slow progression of the disease. In this case, even though the symptoms were mild and nonspecific, the possibility of the EIP tendon’s impairment should not be overlooked. Ignoring the clinical presentations and delaying treatment can result in poor prognosis. In conclusion, early diagnosis and decreasing movement of the involved tendon are important to improve the prognosis of patients.
In the case, postoperative pathology showed pervasion of the synovial mononuclear cells and the multinucleated giant cells were dispersed in the interstitial tissue. Immunohistochemical examination also showed the presence of CD68 (+) and Ki-67(+). We found that, in some cases, the cytoplasm of the synovial mononuclear cells contains deposits of iron-hemoflavin particles [24]. Together, these pathological characteristics contributed to making the final diagnosis. Even so,the differential diagnoses of GCTTS from synovitis, hemorrhages, specific and non-specific infectious arthritis, rheumatoid polyarthritis, synovial hemangioma, synovial osteochondromatosis, synovial arborescence lipoma, and synovial sarcoma should be considered [24,25,26]. Although MRI plays a vital role in initial diagnosis and surgical planning, the final diagnoses are largely made on the basis of histological examination. Additionally, in case of slightest doubt a biopsy should be performed, especially if initial diagnosis confirms the presence of nodular GCTTS.
In conclusion, GCTTS originating from the hands or wrists are usually benign and localized, but in extremely rare cases, there is a possibility of tendon damage. In this report, we detailed a case of GCTTS in the wrist that impaired the extensor indicis proprius tendon. Based on this case, we learned that early radical resection is recommended upon diagnosis,at the same time,the decreasing movement of the involved tendon will be helpful.All these will help to prevent the destructive proliferation of the tumor, maximumly reserve the tendon’s function, and contribute to good prognostic outcomes.
