Successful outcome after intralesional curettage for spindle cell hemangioma of bula: a case report

Background Spindle cell hemangioma (SCH), a non-neoplastic reactive vascular lesion, rarely locates in bones. We herein report a successful case of intralesional curettage for an infant with SCH of bula. Case presentation A 11-month-old male patient was admitted to our center with a painless mass in right proximal calf. Preoperative digital radiograph demonstrated a massive vascular lesion with an irregular bone destruction of proximal bula. The lesion was removed via the intralesional curettage approach and pathologically diagnosed as SCH. After the surgery, the patient gained bone structure recovery of right proximal bula. Two years after the surgery, he experienced no local recurrence. Conclusion For the management of we suggest early-stage as safety and effectiveness.


Abstract
Background Spindle cell hemangioma (SCH), a non-neoplastic reactive vascular lesion, rarely locates in bones. We herein report a successful case of intralesional curettage for an infant with SCH of bula.
Case presentation A 11-month-old male patient was admitted to our center with a painless mass in right proximal calf. Preoperative digital radiograph demonstrated a massive vascular lesion with an irregular bone destruction of proximal bula. The lesion was removed via the intralesional curettage approach and pathologically diagnosed as SCH. After the surgery, the patient gained bone structure recovery of right proximal bula. Two years after the surgery, he experienced no local recurrence.

Conclusion
For the management of SCH of bula with partial bone destruction, we suggest early-stage intralesional curettage as its safety and effectiveness.

Background
Spindle cell hemangioma (SCH), characterized by cavernous blood vessels and spindle cell proliferation, has recently been considered as a non-neoplastic reactive vascular lesion [1,2]. SCH often occurs at early age with high risk of recurrence after surgery, due to its uncertain border with surrounding tissue. It commonly arises in the dermal or subcutaneous tissue of the distal extremities [3,4]. Reports on SCH cases involving bone are rare, most of which focus on histopathological description, but lack su cient clinical and follow-up data [5,6]. Herein, we present a case of SCH in proximal bula that was managed successfully by intralesional curettage, and moreover, discuss its clinical characteristics and long-term surgical outcome.

Case Presentation
A 11-month-old male patient presented to our center with a 2-month history of painless mass in right proximal calf. The mass had been noted to be slowly enlarging in 3 weeks after presentation. No signi cant symptom was found in this patient. Initial workup performed included radiograph, 3dimensional computed tomography (3d CT) reconstruction, and magnetic resonance imaging (MRI).
Radiographs of the right tibia and bula indicated an irregular bone destruction of proximal bula (Fig. 1a, b), and the lytic bone destruction was con rmed by 3d CT reconstruction (Fig. 1c, d). MRI revealed a massive vascular tumor with surrounding soft tissue hyperplasia, and involvement of the proximal bular epiphyseal plate (Fig. 1e, f).
Considering partial bony structure of proximal bula was normal, intralesional curettage was performed on the right proximal bula under general anesthesia. After lesion exposure, a 4.0×2 .0 cm-sized vascular mass was identi ed with extension to proximal bular. Gross examination showed a reddish spongious solid mass, containing topical hemorrhage, partial thrombosis, and irregular bone destruction (Fig. 2a).
With protection of common peroneal nerve and peripheral vessels, complete curettage of lesion was performed to normal bular surface (Fig. 2b, c). Histologically, the lesion was characterized by the ssurelike vessel lumens lined with attened endothelial cells among the spindle cells (Fig. 3a). The spindle shaped cells arranged in fascicular pattern in solid area, with similar cell morphology and no atypia (Fig. 3b, c). Immunohistochemically, the endothelial cells lining the vessel spaces stained positive for CD31, CD34, and ERG. Therefore, with standard of international society for study of vascular anomalies (ISSVA) classi cation [7], the diagnosis of spindle cell hemangioma was made in this patient according to the clinical and histopathologic manifestations. On postoperative follow-up, this patient was asymptomatic without any evidence of recurrence (Fig. 4). Two years after this surgery, he returned to hospital for outpatient review. Radiographs showed the reformation of the cortex of the proximal bula (Fig. 5a, b), and both uniform bone mineral density and continuous cortical of right proximal bula were con rmed by 3d CT reconstruction (Fig. 5c, d). Besides, MRI demonstrated remarkable regression of lesion without any signs of tumor growth through the bula (Fig. 5e, f).

Discussion
This case is rare in comparison with majority of reported SCH cases and merits discussion on following points: location of lesion, selection of surgical intervention, histopathologic characteristics, and long-term postoperative follow-up. SCH is a benign vascular lesion which generally locates in the subcutis at the distal extremities and presents as solitary and multifocal masses. It also can be associated with several clinical syndromes, among which Maffucci syndrome is the most common [8,9]. In several uncommon cases, SCHs have been found in lips, nasal passage, temporal muscle, and even in lungs and spleen [2,[10][11][12][13]. In comparison, the reported cases of SCH arising in bones are even more unusual so far [14][15][16].
In our case, a solitary lesion of SCH involved the proximal bula with surrounding soft tissue hyperplasia, while the super cial skin and tissues were normal.
To date, the main treatment choice for bular tumor is segmental or subperiosteal resection, in case of local recurrence at surgical site [17][18][19]. Given that preoperative digital radiograph indicated that the vascular mass on bula was solitary, and part of both cortex and cancellous bula were not involved, intralesional curettage was selected as the surgical intervention in this case for achieving the maximum retention of healthy bony structure. During the operation, complete curettage was performed to the normal bular surface without residual lesion.
The histologic appearance in this case consisted of the ssure-like vessel lumens lined with attened endothelial cells among the spindle cells, which arranged in fascicular pattern in solid area. Subsequent immunohistochemical analysis revealed positive staining for CD31, CD34 and ERG in the majority of spindle cells, consistent with the diagnosis of SCH [20,21]. Metastasis of SCH is rare, although local Page 4/10 recurrence may occur [22,23]. On the most recent imaging examination, 2 years after the initial surgery, our patient was still disease-free and found to experience entire reformation of bone structure of right proximal bula. This indicates the safety and effectiveness of intralesional curettage for the management of this case.

Conclusions
For SCH of bula with partial bone destruction, intralesional curettage renders a safe and e cient intervention at early stage.

Declarations
Ethics approval and consent to participate Not applicable.

Consent for publication
Written consent for publication was obtained from the parents of the patient for publication of this case report and accompanying images.

Availability of data and materials
All data generated during this report are included in this published article.

Competing interests
The authors declare that they have no competing interests.   The photograph during the surgery: a intraoperative image of the surgical nding of a vascular mass attached to proximal bula; b complete curettage of lesion to normal bular surface; c macroscopic appearance of the excised lesion.   a Digital radiograph at 1 month follow-up, b 6 months postoperatively.