Osteochondroma of the Scapula: A Case Report and Literature Review

Osteochondromas are bone lesions composed of medullary and cartilaginous bone covered by a cap of hyaline cartilage. The presence of medullary and cortical bone with the continuity of the tumor is pathognomonic for osteochondroma and aid in establishing the diagnosis. We report a case of a two-year-old girl who presented to our clinic following her mother noticing a palpable, growing, and painful mass on her left scapula. There was no limitation in the range of motion. A clear-cut mass was seen on the dorsal aspect and palpated measuring around 2.5x3 cm. Surgical excision of the mass followed by histologic examination confirmed osteochondroma. Upon follow-up, the patient had no pain and had a full range of left shoulder motion without discomfort or pain. In conclusion, scapular exostoses are very rare and more so when they present dorsally. Symptomatic lesions can be managed effectively with surgical excision of exostosis.


Case Presentation
We report a case of a two-year-old girl who presented to our clinic following her mother noticing a palpable growing and painful mass on her left scapula for 18 months. No limitation in the shoulder and scapulothoracic joint's range of motion was appreciated. No similar history among other family members was present. A well-defined round mass was seen on the dorsal aspect and palpated measuring 3 x 2.5 cm ( Figure 1).

FIGURE 1: Presentation of the patient with scapular exostosis where her parents noted the lump on her back
The mass was severely painful, especially in the supine position. A CT scan confirmed the diagnosis of osteochondroma ( Figure 2).

FIGURE 2: CT scan showing exostosis of the left scapula
A nuclear bone scan was done, which concluded the presence of focal uptake in the left scapula corresponding to moderate osteoblastic activity with regular contours and mild sclerotic changes, which were likely related to exostosis, with no other lesions in the body noted on the scan. X-rays showed a bony growth on the dorsal aspect of the scapula ( Figure 3).

FIGURE 3: Preoperative X-ray taken for the evaluation of the patient
The decision to go for surgical removal with a safety margin was made. The patient was placed in a prone position under general anesthesia. An incision was done right above the mass, separating the muscle directly from the mass, and excising the mass from the base so that no residual part of the mass is left behind. The stalk of the exostosis was excised at the base with an osteotome from the dorsal surface of the scapula (Figure 4). The specimen measured 3× 2.5cm. Histologic examination confirmed that the specimen was an osteochondroma with no signs of malignant transformation.

FIGURE 4: Surgical excision of the mass
The patient improved immediately in terms of pain and was followed up in the clinic regularly. Within almost a year, the patient had no pain, and had a full range of left shoulder motion without discomfort or pain. Follow-up X-rays showed no evidence of recurrence ( Figure 5). The patient has not developed any recurrence as of now and will be continuously followed up in the clinic to check for any recurrence.

Discussion
As noted previously, osteochondromas of the scapula account for 4% of all bone tumors occurring in the scapula [38,43]. Mostly, osteochondromas are identified in the first or second decades of life, given that the tumor's growth usually stops when the physis closes; moreover, they are mostly asymptomatic [67,68]. Our case presents a symptomatic mass in a two-year-old noted by her mother, which in some ways is similar to multiple other papers found in the literature from different age groups, which had a similar presentation ( Table 1) [14,42,43,[58][59][60][61]. The novelty of our case is in the age of presentation, which is extremely rare in the literature.   Moreover, some cases reported worsening pain (Table 1) [42,48,50,51,59], and others reported difficulty sleeping in the supine position [42,59,60]; furthermore, some cases presented limitations in the range of motion of their joints [43,47]. Most osteochondral lesions of the scapula have been noted to be situated along the scapular equator; however, larger lesions tend to be situated in the inferior aspect of the scapula due to a lack of space restriction [67,69]. Diagnosing osteochondroma is typically clinical and radiologically followed by histological confirmation [44,67,70].
Generally, osteochondromas are managed after skeletal maturity to avoid injuring the growth plate during surgery [46,71], given that with longitudinal growth, the tumor migrates from the metaphysis to the diaphysis and away from the growth plate, which decreases the chances of injuring the growth plate [71]. In the event where cosmesis and pain are the patient's main concern in scapular exostosis, excision can be done at a younger age, such as in our case, if planned carefully and executed by the most senior surgeon of the operating team.

Conclusions
Osteochondromas of the scapula, although benign, are at risk of being left unnoticed until malignant transformation occurs, like other central osteochondromas; therefore, we routinely advocate the removal of scapular osteochondromas at presentation. Excision after diagnosis can be done in a meticulously planned manner to avoid iatrogenic injury to the growth plate and ensure complete excision at the base of the stalk. The patient's family is very grateful for the full recovery of their daughter and is satisfied with the results.

Additional Information Disclosures
Human subjects: Consent was obtained or waived by all participants in this study. King Saud Medical City IRB issued approval H2RI-08-May 22. We are pleased to inform you that the above-referenced case report has been reviewed and no ethical issue was found. The drafted case report is scientifically sound and approved by the Research & Innovation Centre for submission to the journal for publication. Conflicts of interest: In compliance with the ICMJE uniform disclosure form, all authors declare the following: Payment/services info: All authors have declared that no financial support was received from any organization for the submitted work. Financial relationships: All authors have declared that they have no financial relationships at present or within the previous three years with any organizations that might have an interest in the submitted work. relationships or activities that could appear to have influenced the submitted work.