Neeraja Myreddy1, K. P. Varalakshmi2, P. Sravani3, B. Chaitanya4
1Neeraja Myreddy, M.D,2K.P.Varalakshmi, M.D,3P. Sravani, M.D,4B. Chaitanya, M.D. All are affiliated to Dr. NTR University of Health sciences, Vijayawada, Andhra Pradesh, India.
Address for correspondence: Dr B Chaitanya, Email: bharadwaj.chaitanya@yahoo.com
Abstract
Osteochondromas is one of the common bone tumour account for 35-46% of cases. These are most commonly seen on the metaphysis of a long bone, but they can arise from any bone which is preformed from cartilage and also involves flat bones like ilium and scapula. Scapular involvement is noted in 3 – 4.6 % of cases and patients usually are affected by winging of scapula. It is common in young patients, usually below 30 years of age, with a ratio of males to females of 2:1. We present a male patient diagnosed with solitary asymptomatic scapular osteochondroma with review of literature.
Keywords: Osteochondroma, Scapula, Cartilage.
Manuscript received: 10th July 2014, Reviewed: 12th July 2014
Author Corrected: 25th July 2014, Accepted for Publication: 11st August 2014
Introduction
Osteochondroma is a cartilage capped bony projection arising on the external surface of bone containing a marrow cavity that is continuous with that of the underlying bone. Synonymously known as exostosis, it is most commonly located in the distal femoral, proximal tibial or proximal humeral metaphysis of adolescents and young male adults [1]. Osteochondromas generally arise in bones preformed by cartilage. Involvement of flat bones is less common with the ilium and scapula accounting for most of the cases. Majority are asymptomatic per se while a few are known to cause secondary complications. They may be sporadic, solitary or multiple and inherited due to germline mutations of EXT 1 and EXT 2 tumour suppressor genes [2]. We present a classical case of solitary sporadic sessile asymptomatic osteochondroma in a young male.
Case Report
A 22 year old male patient presented to the Orthopaedics department with complaints of a painless swelling over the scapula of six months duration. The swelling progressed in size gradually. There was no history of trauma and associated symptoms or other swelling elsewhere. No rapid increase in size was observed. Family history was insignificant. On examination a hard, irregular bony swelling of size 4 x 4 cm was palpable on the dorsum of right scapula [Figure 1]. The swelling was fixed to the underlying bone. Skin over the swelling was normal and freely mobile. There was no localized tenderness. There were no other musculo‑skeletal abnormalities. Laboratory data was within normal limits. X‑ray showed a sessile, cauliflower‑like calcified growth on postero medial aspect of scapula. Computed tomography (CT) scan described a well defined lytic lesion with irregular border and medullary continuity measuring 4.1 x 2.3 x 4 cm noted arising from posterior aspect of medial border of scapula just inferior to scapular spine. There is a thin rim of cartilaginous cap surrounding the lesion [Figure 2]. A clinical diagnosis of osteochondroma was considered and surgery planned. Wide local excision of the lesion was done under T1, T2, T3 paravertebral block. The tumour was sessile and friable and so could not be removed in toto as a single mass. Grossly, the lesion was friable, cartilage capped. All the tissue bits obtained were processed and H & E sections revealed a cartilaginous cap with haphazardly arranged chondrocytes with benign morphology and underlying bony trabeculae with interspersed fatty, hematopoietic marrow [Figure 3]. A histopathological diagnosis of osteochondroma was rendered. Follow up of the patient so far showed no recurrences.
Figure I: Clinical photograph showing right scapular swelling in a young patient.
Figure II: Axial CT film showing irregular sessile lesion on posteromedial aspect of right scapula
Figure III: Microscopic photograph showing cartilage capped lesion with marrow elements within bony spicules, H & E,
Discussion
Osteochondromas are benign tumors composed of spongy bone covered by cartilaginous cap. Majority of them are sporadic and solitary. Less commonly, it occurs as multiple lesions with autosomal dominant pattern of inheritance. It was long debated whether osteochondroma was a developmental disorder or a true neoplasm. The etiology is not known. Based on the resemblance of the cartilage cap to the growth plate, several hypotheses have been offered. These include the possibility of breakage, rotation and aberrant growth of the epiphyseal plate or herniation of the plate in the metaphysic [3]. Cytogenetic studies have implicated the Knudson’s two hit hypothesis on EXT 1 AND EXT 2 tumour suppressor genes resulting in truncated / non functional protein. The mutations were described to induce cytoskeletal abnormalities in osteochondroma chondrocytes [4]. DNA flow cytometry of the cartilaginous cap demonstrated aneuploidy (DNA index range 0.88-1.17) [5].
Osteochondromas can be found in any bone preformed by cartilage. Most lesions are found during the period of rapid skeletal growth, and their growth usually ceases by skeletal maturity. Involvement of the flat bones, ilium, and scapulae occurs in about 5% of patients. Majority are asymptomatic, slow-growing mass detected as an incidental finding by radiography. Pain is usually caused by compression of adjacent structures or due to the fracture of the stalk. Grossly an osteochondroma presents as an exophytic, sessile or pedunculated (with a stalk) projection of bone capped by cartilage. Importantly, the osteochondroma demonstrates both medullary and cortical components that are contiguous with the medulla and cortex, respectively of the underlying native bone. On imaging studies, the lesions appear as either a flattened (sessile) or a stalk-like (exostotic) protuberance on the bone shaft in a juxtaepiphyseal location. CT scan or MRI images typically show continuity of the marrow space into the lesion. These modalities may also predict the thickness of the cartilage cap [6]. Microscopically osteochondroma mimics an epiphyseal growth plate beginning with a thin (usually <1 cm) cartilaginous cap superficially, a zone of endochondral ossification followed by regular trabecular bone surrounded by fatty, hematopoietic marrow. Occasionally, degenerative change and calcification are seen in the cartilage cap.
Osteochondromas can potentially transform into malignancy. The features that should raise suspicion of malignancy include :
1. Clinically – any recent rapid increase in size with associated pain, multiplicity with involvement of proximal skeleton and multiple recurrences
2. Radiographically - irregularity of the margin, inhomogeneous mineralization, an associated soft tissue mass.
3. Grossly – a thick irregular cartilage cap greater than 2 cms
4. Microscopically – Loss of the architecture of cartilage, wide fibrous bands, myxoid change, increased chondrocyte cellularity, mitotic activity, significant chondrocyte atypia, necrosis and permeative growth into surrounding soft tissues.
Differential diagnosis include parosteal osteosarcoma, Nora’s lesion (bizarre parosteal osteochondromatous proliferation) and tori (Exostoses in the cranio-facial and jaw bones in response to irritants). Histopathology with radiological correlation provides conclusive opinion on diagnosis.
Surgical excision is often curative for osteochondromas. Arthroscopic resection can also be successfully performed. Removal in toto may be difficult in sessile tumours. Clean surgical margins help to prevent recurrences and to manage chondrosarcomas [7]. Secondary complications include mechanical obstruction, nerve impingement, pseudoaneurysm of an overlying vessel, infarction of the osteochondroma or fracture of the stalk of the lesion[2]. The thickness of the cap decreases with advancing age and may trigger the formation of a bursa.
Conclusion
The present case report describes a considerably rare entity 5 ‘S’ osteochondroma – Sporadic, Solitary, Sessile, Symptomfree and Scapular.
Funding: Nil, Conflict of interest: Nil
Permission from IRB: Yes
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How to cite this article?
Neeraja Myreddy, K P Varalakshmi, P Sravani, B. Chaitanya. Usual Tumour at an Unusual location – Solitary Sporadic Scapular Sessile Osteochondroma. Int J Med Res Rev 2014;2(4):403-406.doi:10.17511/ijmrr.2014.i04.025