A 78-year-old man presented with omalgia and a 3-month hard-mass in his right shoulder. He didn't have any clinical history of interest.
An X-ray, a CT scan and an MRI of the right shoulder were performed, as well as an US-guided biopsy to confirm the diagnosis. It was completed with thoracoabdominopelvic CT.
The X-ray (Fig. 1) and CT (Fig. 2) showed a mixed lytic-sclerotic lesion in the distal third of the right clavicle with a spiculated sunburst periosteal reaction and a soft-tissue mass associated, which was responsible for the visible lump. MRI (Fig. 3) more precisely showed the soft-tissue component of the lesion with lobulated well-defined borders around the clavicle, which also affected the surrounding structures.
The thoracoabdominopelvic CT showed a second bone lesion in the right hemipelvis (Fig. 4). Finally, the US-guided biopsy of the clavicle’s soft tissue mass (Fig. 5) confirmed the prostatic origin.
When faced with a bone lesion, periosteal reaction is an important finding to take into consideration. Four types can be distinguished: solid, lamellated, spiculated and Codman's triangle [1,2]. The spiculated pattern is linked to aggressive lesions which strip the periosteum from the cortical bone, leaving behind a loose attachment of residual Sharpey’s fibres between them. New bone then forms along, resulting in the characteristic spiculated appearance [3,4]. Two subtypes can be distinguished: the hair-on-end subtype (spicules grow perpendicularly to the bone cortex) and the sunburst subtype (spicules grow in a divergent pattern). The former is more likely related to osteolytic tumours such as Ewing’s sarcoma and the latter to osteoblastic ones such as osteosarcoma . However, apart from primary bone tumours, it can also result from metastases or infections, and more rarely, trauma or stress [6,7].
Periosteal reaction can occasionally occur in osteoblastic metastases, specifically prostatic ones [3,4,8,9,10]. In one report, the incidence of periosteal reaction of any kind associated with prostatic bone metastases was found to be 5% . Conversely, extraosseous soft-tissue masses are more common in osteolytic metastases [11,12] and are scarce in breast and prostate cancer .
Our patient presented a rapidly growing lump in his right clavicle, showing in the X-ray a mixed lytic-sclerotic bone lesion with sunburst periosteal reaction and an extraosseous soft-tissue mass associated. At first, these findings suggested a primary malignant bone tumour. Due to the patient’s age, it was thought to be an osteosarcoma because a second peak of incidence has been described in elder people, especially associated with previous bone diseases such as Paget’s disease.
Afterwards, we completed the study of local and distance extension of the tumour with MRI and thoracoabdominopelvic CT, respectively. This CT revealed a second bone lesion with similar characteristics in the right hemipelvis. Said finding suggested the possibility of multicentric metastatic disease versus osteosarcoma. Hence, a tumour markers blood test was made revealing an elevated PSA level of 118.00 ng/mL, compatible with prostate adenocarcinoma . An ultrasound-guided biopsy of the clavicle’s soft-tissue mass confirmed the diagnosis.
When bone metastases associate an extraosseous soft-tissue mass, initial PSA levels tend to be higher and a good response to hormonotherapy is also expected .
Take home message: in light of a bone lesion showing aggressive radiological features (such as the aforementioned), a metastatic origin cannot be disregarded, especially in patients over 40 years of age. If osteoblastic, prostatic or breast cancer must be suspected.
Written informed patient consent for publication has been obtained.
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