Endgames Spot diagnosis

A painless lump in the arm

BMJ 2016; 354 doi: https://doi.org/10.1136/bmj.i4503 (Published 13 September 2016) Cite this as: BMJ 2016;354:i4503
  1. Shahrukh Raees Ahmad, foundation year 2 doctor1,
  2. Raees Bhatti, 4th year medical student2,
  3. Gulraiz Ahmad, radiology registrar3
  1. 1Pennine Acute Hospitals NHS Trust, Manchester, UK
  2. 2University of Liverpool, UK
  3. 3North West School of Radiology
  1. Correspondence to: S R Ahmad shahrukh.ahmad{at}doctors.org.uk

A 15 year old boy presented to his doctor with a painless palpable lump in his right upper arm. He had had it for “many years,” but was now conscious about it. A plain radiograph of the arm showed multiple bony lesions (fig 1). What is the diagnosis?


Fig 1 Anteroposterior radiograph of right upper arm


Hereditary multiple exostoses (also known as diaphyseal aclasis) (fig 2).


Fig 2 Anteroposterior radiograph of right upper arm. Osteochondromas can be sessile (broad arrow) or pedunculated (fine arrow) and tend to grow in the metaphyseal region projecting away from the epiphysis


Hereditary multiple exostoses is an autosomal dominant condition, with incomplete penetrance in females.1 It is characterised by the development of multiple benign bone tumours known as osteochondromas.

Osteochondromas usually develop during childhood and stop growing once skeletal maturity has been reached. They are chondroid neoplasms and are associated with an overlying hyaline cartilage cap.

Most patients with hereditary multiple exostoses are asymptomatic. Common symptoms include a palpable lump and neural or vascular compression due to mechanical effects of the osteochondroma.2 Fractures through the neck of pedunculated lesions have also been reported, as well as short stature in as many as 40% of cases.3

There is a 3-5% increased risk of malignancy with hereditary multiple exostoses.4 The malignant transformation is almost always associated with the formation of chondrosarcoma in the hyaline cartilage cap. Suspect malignancy if patients who have reached skeletal maturity have a cartilage cap thickness of greater than 1.5 cm and new onset pain in an established osteochondroma.

Use computed tomography and magnetic resonance imaging to characterise lesions. In most cases, no treatment is required. Local resection may be carried out for mechanical reasons or where there is a suspicion of malignant transformation.

Patient outcome

Further imaging of areas where the patient felt a palpable lump (figs 3-5) was undertaken. MRI of a chest wall lesion revealed benign appearances of an osteochondroma. The osteochondroma in the right upper arm was locally resected for cosmetic reasons.


Fig 3 Lateral radiograph of left femur


Fig 4 Anteroposterior radiograph of left femur


Fig 5 Posteroanterior radiograph of chest. Osteochondromas can grow in flat bones such as ribs


  • Competing interests: We have read and understood BMJ policy on declaration of interests and declare: none.

  • Provenance and peer review: Not commissioned; externally peer reviewed.

  • Patient consent: Obtained.


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