Discussion

CCS is mainly located in the extremities and most frequently between the second and fourth decades of life, without sex predilection and only 10-20% are in the hand-wrist region [8].

Clinically, it is a slow-growing and mobile tumor; sometimes it can cause neuropathy due to nerve compression [2,8]. It tends to spread rapidly, presenting metastases at initial diagnosis in up to a third of cases [3]. Our patient's tumor had been evolving for two years and presented dimensions of 4.8 x 3.4 x 4.9 cm, without sensorineural compromise or metastasis data. A tumor size > 5 cm has been described as associated with poor survival (≤ 5 cm vs > 5 cm: 83% vs 25%) at five years [6].

Ultrasound techniques can detail a multilobulated, heterogeneous, and densely vascularized mass, suspicious of malignancy [7]. However, MRI is the diagnostic imaging method of choice; it delineates the edges of the lesion, the extent of edema, and fat involvement to support adequate surgical planning [5,11]. MRI was the reference method in our case.

For the approach, the biopsy is ideally percutaneous with an image-guided core needle, performing CT staging of the chest and abdomen [8]. In the case presented, an incisional biopsy without guidance and a chest CT scan were performed, ruling out the possibility of metastasis or adenopathies.

Preoperative radiotherapy has been reported to be useful in cases of neurovascular contact, facilitating the resection of negative margins by inducing a pseudocapsule and reducing tumor size [8]. In this sense, the reported patient achieved a significant reduction of approximately 80% in tumor size with preoperative radiotherapy. The general recommendation for adjuvant radiation therapy is made in high-grade, deep, and large (>5 cm) lesions, as in our case [3].

Currently, the most important and curative treatment is complete surgical resection (primary or secondary R0) with negative margins [3], which often involves amputation of the hand. Incomplete resection (R1) with positive margins has been associated with a local recurrence of 100% at two years [6].

With wide resection, mutilating surgeries such as triple central beam amputation [12] or even partial amputations of the hand are described [13]. These aggressive approaches do not improve the recurrence rate and should only be considered when the resection would lead to severe functional impairment, which could not be reconstructed, or presents considerable complications [3,8]. If lymph node involvement is suspected, dissection/biopsy should be considered, and if positive, lymphadenectomy should be considered, as it is an independent prognostic factor for recurrence and survival [8,14].

With tumor resection, defects composed of skin-to-bone involvement can be obtained, affecting one or more metacarpals. Therefore, a free OCF is a good reconstructive option since OCF can provide the greatest amount of bone tissue, and its intrinsic characteristics are more similar to the metacarpals that were removed [15,16]. In the case described, resection of the third, fourth and fifth MTC and a large part of the carpal bones was necessary.

The fibula-free flap has been an abutment for reconstruction of long bone defects, especially in mandibular reconstruction. The preservation of 6 cm of the fibula head can avoid complications, and it has to be limited to 4 cm [16]. Its use is ideal for metacarpal reconstruction, both for traumatic defects and for tumor resection [15], as in the case of the study.

Among the advantages of the OCF are its reliable skin pedicles, long and thin bone well vascularized with simple extraction in segments, long and good caliber vascular pedicle, a short learning curve and minimal morbidity in the donor area [15]. However, this flap is not exempt from complications such as necrosis of the cutaneous pedicle or sequelae, which, although rare, there is the possibility of graft loss in the donor area, weakness of the flexor longus hallucis and painful neuroma of the sural nerve up to gait alteration [15,16]. In our case, the cutaneous pedicle presented a small area of necrosis in its periphery, which was delimited and healed without complication.

The metastasis/recurrence risk factors include high histological grade, positive borders, 5 cm >lesion, and vascular invasion and deep plane [5,8]. The tumor treated had a dimension of ~6.5 cm diameter and the histological diagnosis of a clear cell sarcoma was confirmed with FISH (+) for rearrangement of the _ewsr_1 gene.

Follow-up MRI or CT scan is recommended every one to two years to look for recurrences or metastases, mainly to the lung (80%) and bone [5,8]. In the follow-up of our case, no abnormalities have been observed in the directed auscultation of the hand, and no recurrences were reported in six months. However, this report has limitations, especially regarding follow-up, as it was only possible to conduct it up to six months post-surgery. Furthermore, assessments using validated scales such as DASH [9], MSTS [10], or grasping abilities could not be performed due to the loss of contact with the patient. Of course, the findings and results of this report, which is based on a single-patient study, cannot be generalized to other patients with similar cases, but they could definitely help guide surgical planning and execution for limb salvage in these complex cases.