Figure 6: Post-operative image of the thumb at 1 month of GCTTS excision.
Discussion
This case was intended to report a rare case of giant cell tumor tendon sheath of distal phalanx. Giant cell tumors most commonly affect the first three fingers, with the index finger being the most frequently involved and in this patient, thumb was the site of lesion [5,7,8]. These tumors are most commonly found in the region of the distal interphalangeal (DIP) joint, followed by the proximal phalanx similar to this study [9,10].
GCTTS manifests clinically as a firm, painless, gradually growing focal mass likely to impair the function of the involved tendon and joint [3,4]. A plain radiograph commonly detects any soft tissue swelling and also determine whether a fracture, dislocation, or destructive lesion exists [5]. In this case, there was no joint restriction, fracture, dislocation or bony destruction which may be due to early presentation to the hospital. Sonography can be used to distinguish between solid and cystic lesions, its relationship with the surrounding structures and to detect satellite lesions [5,11]. MRI is the preferred imaging modality, particularly for evaluating extra-articular manifestations [5,12]. In this specific case, a hypoechoic complex solid looking cystic lesion was detected on ultrasonography, however MRI was not performed due to unaffordability of the patient.
In this patient, GCTTS and ganglion cyst were the differential diagnoses we came up with based on the history, clinical and radiological examination. An ultrasound revealed that a ganglion cyst was more likely than a giant cell tumor. Complete surgical excision is the primary treatment for GCTTS [5]. In this case, the mass was excised in toto. Because of the presence of a pseudocapsule, the tumor is frequently removed as a whole [5]. However, after surgical excision, the tumor’s characteristics were more suggestive of a giant cell tumor, indicating histopathological confirmation. A histopathological examination of the excised tissue was performed, which confirmed the diagnosis of GCTTS. Hence, histopathological examination is a must to confirm the diagnosis [6,13].
Recurrence is a major risk factor. Given the reported high recurrence rate of up to 45%, long-term follow-up after excision is advised [6,7]. The recurrence was significantly higher at the thumb interphalangeal (IP) and distal digital interphalangeal (DIP) joints [1]. The reason may be the difficult excision of the tumor distally at the proximal interphalangeal (PIP) joint or the thumb IP and DIP joint due to the proximity of neurovascular structures to tumor margins [14].
The patient was then evaluated 10 days later in the out patient department. The patient had an uneventful post-operative course and continues to do well at 1 month post surgery with no complaints and no signs of recurrence which was in line with a similar study by Boeisa and Khalaf [7].
Conclusions
This study presents a rare case of giant cell tumor tendon sheath of distal phalanx thumb and its diagnosis and treatment in a resource constraint country. This study also emphasizes on the significance of histopathological examination for the confirmation of diagnosis.
Conflict of interest: None
Source of funding: No source of funding
Acknowledgement: I would like to show my gratitude to Dr Anand Chaurasia, Department of Pathology, for providing the diagnostic histopathological findings.
Ethical clearance: Not applicable.
Consent: Written informed consent was obtained from the patient for publication of this case report and any accompanying images.
Data availability statement: Data available on request from the authors.
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