Osteochondroma, as an orthopedic entity sits tightly on the fence between neoplastic and non-neoplastic lesions. Although considered as a benign bone tumor, it represents a developmental aberration involving ectopic migration of a part of the growth plate and its autonomous proliferation ^[1]. The lesion consists of a bony mass and overlying cartilage, with its cortex and medullary cavity contiguous with those of the originating bone. Its growth also mirrors the growth of its parent bone and peaks at skeletal maturity, unless it transforms into a malignant lesion [2, 3]. It is mostly found as a solitary lesion but may present as multiple lesions in a condition known as multiple hereditary exostoses [4, 5]. Owing to its asymptomatic nature, it is usually found incidentally on imaging or occasionally presents as a painless lump. Rarely, it might present with pain because of mechanical irritation of adjacent structures including muscles and tendons, or if there is a malignant transformation of the lesion [6, 7]. The distal femur, proximal tibia, and proximal humerus constitute the most common sites of presentation of osteochondroma ^[8]. The scapula is a relatively rare site, but osteochondroma is the most common tumor of the scapula. Most scapular osteochondromas present on the ventral aspect, with the dorsal side relatively less involved and less reported [9-12]. We report a case of large dorsal scapular osteochondroma in a young male.

A 21-year-old young adult presented with a swelling over the right upper thoracic region. The swelling was first noticed by the patient around 9 years ago, as a peanut-sized lump which progressively grew to about the size of a golf ball at the present day. There was no history of any significant trauma or any other lump. It was painless for the majority of its duration but started causing discomfort in the past 2 months before the presentation. Due to its asymptomatic nature for much of the course, the patient avoided any surgical treatment advised to him multiple times. On examination, the swelling was solitary, protuberant, localized, spherical, and non-pulsatile. The overlying skin was unremarkable and there was no change in local skin temperature. Swelling was non-tender and globular with dimensions of 5.5 cm × 6 cm × 3.5 cm. Bony hard consistency was evident with clearly defined edges. The swelling was fixed to the underlying scapula, a few centimeters above the inferior angle. It was non-fluctuating and non-reducible. There was a movement of the swelling corresponding to the movements of the scapula. Neurovascular examination of the right upper limb was unremarkable (Fig. 1).

A biopsy sample was taken and sent for histopathological examination. The report suggested a chondroid lesion with the focal osseous component. Findings were consistent with osteochondroma without any element of sarcomatous changes.

En bloc excision of the lesion was planned. The patient was taken on the operation Table 1 in a prone position under the effect of general anesthesia. A 7.5 cm incision was taken centered over the swelling and parallel to the medial margin of the scapula. The muscle was separated along the plane created by the tumor above the mass and the base of the mass was accessed from all directions. It was dissected with the periosteum and excised along with the periosteum from the base with the help of an osteotome. The specimen measured 6 cm × 5.5 cm × 3.5 cm (Fig. 4 and 5).

The patient had immediate relief postoperatively. He was called for follow-up at 15 days, 1 month, 2 months, and 3 months postoperatively and assessed clinically and functionally. There was no pain or reappearance of swelling. Shoulder range of movements and scapulo-thoracic rhythm were normal at 3 months postoperatively (Fig. 6 and 7).

Despite the common occurrence of osteochondromas, the scapula remains a relatively less common site. This can be explained by the fact that scapula ossifies through intra-membranous mode while the most acceptable paradigm of the pathogenesis of osteochondroma is the migration of growth plate remnants to an ectopic location [13, 14]. However, there is a caveat, that osteochondromas constitute the most common tumor of scapula and the most common site is the ventral surface [15-19]. Usually, they follow the growth and development of the parent bone and are present in 2^nd or 3^rd decade of life. They are mostly asymptomatic but may irritate adjacent structures leading to a myriad of signs and symptoms. Although plain radiography forms the gold standard imaging modality for their diagnosis, suspected osteochondromas of scapula require MRI. MRI is advised when a malignant transformation is suspected. Most asymptomatic lesions are treated conservatively but symptomatic lesions usually require surgery. Our case had a more rare presentation as the tumor was on the dorsal surface. We have also reviewed similar case reports (Table 1).

Dorsal scapular osteochondromas are a rarity. Here, we have reported a case of a 21-year-old male patient with a globular swelling on the upper back associated with discomfort. After making a diagnosis after radiological and histopathological examination, the decision of en bloc excision of the lesion was taken in view of symptoms.

A mindfully rehearsed sequence of diligent history-taking, careful clinical examination, appropriate imaging, and biopsy is required for the diagnosis of osteochondroma at a location as rare as the dorsal scapula. En bloc excision is the choice of procedure if the indications for surgery are met.