An unexpected supraclavicular swelling
© Patel et al; licensee BioMed Central Ltd. 2007
Received: 05 February 2007
Accepted: 04 August 2007
Published: 04 August 2007
Colorectal cancer is the third commonest cause of cancer death in UK. It commonly metastasises to the liver but rarely to small bones.
We describe a case of a patient with adenocarcinoma of the descending colon who presented preoperatively with a right supraclavicular swelling. Subsequent imaging and cytology of the lesion revealed this to be a metastasis to the right clavicle resulting in a pathological fracture.
This report describes the rare occurrence of a colorectal metastasis to the clavicle. It emphasises that although bone metastases from primary colorectal tumours are rare events, they tend to metastasise to small, non-weight bearing bones. It also discusses the utility of isotope bone scanning and that on certain occasions this imaging method may prove to be equivocal. In such circumstances, biopsy or magnetic resonance imaging is more sensitive for the detection of bone metastases.
Colorectal cancer is the third commonest cause of cancer death in the UK. It commonly metastasises to the liver (nearly 50%) , the other sites being lung, brain and bones. Metastasis to the clavicle is extremely rare and in this article, we report one such case of an unusual presentation of clavicular metastasis from a primary colonic malignancy not detected on the isotope bone scan.
A 68 year old man presented with a change in bowel habit and weight loss. General and abdominal examinations were normal. A barium enema revealed a tight stricture in the descending colon, with no evidence of extra-colonic metastases on a staging CT scan. A multi-disciplinary decision was taken that he should be treated with a left hemicolectomy.
The patient had a stable postoperative course and was subsequently discharged home. Out-patient follow-up with the palliative care physicians was arranged and he received palliative radiotherapy to his clavicle and spine. Unfortunately, he died 2 months later.
Colorectal cancer is the third leading cause of cancer-related deaths in the world . Colorectal cancer metastases are mainly seen in the liver (50%), lung (16%), skin (8%) and brain (8%). The incidence of skeletal metastases varies from 4 – 6%  and commonly arise in the pelvis or vertebral bones and rarely as an isolated bony metastatic lesion.
A detailed literature review showed that the clavicle is a very unusual site for metastasis from colorectal cancer and so far has been reported only once . Bony metastases from primary colonic tumours do not have a clear pattern. They are mostly blood borne, probably through veins and they metastasise via the vertebral venous plexus to the vertebrae, pelvic bones, sacrum, skull, femur and humerus . Occasionally, rare metastases to metacarpals, patella, sternum and mandible have been reported [4–6].
Osseous metastases are rarely a primary manifestation of bowel cancer  and are usually associated with other systemic manifestations in the liver, lung or brain . The median time to bony metastasis varies from 7 to 13 months  with most of these arising from highly advanced rectal or sigmoid cancers . One of the reasons for the increase in bony metastases at unusual sites could be improvements in adjuvant treatments resulting in improved survival, thus allowing time for the manifestation of atypical metastases.
Due to the rarity of skeletal metastases from colorectal cancer radiological investigations are undertaken only on clinical suspicion ; in our case the swelling was over the medial end of the clavicle. Most bony metastases are osteolytic and are described as a lesion greater than 1 cm in diameter with loss of 50% of the bone density, but occasionally they are osteoblastic . Isotope bone scanning using Technetium 99 m phosphate compounds is probably used as the principal tool for diagnosing bone metastases. Although, it is more sensitive as compared to radiography, it fails to detect metastases on certain occasions . Plausible explanations for false negative findings are pure osteolytic lesions growing rapidly, when bone turnover is slow, or when the site is avascular. Hence in case of equivocal findings alternative methods in terms of traditional needle biopsy  or more recently magnetic resonance imaging  can be used for diagnosis. Sometimes abnormal biochemistry can indicate bony metastases e.g. raised calcium or/and Alkaline phosphatase.
This case report highlights that a high degree of suspicion should be employed in colorectal cancer patients presenting with bone pain or lesions. There is a need for caution when using isotope bone scanning for detecting bone metastases. With improved colorectal cancer survival and improved quality of care, it may be necessary to consider using bone scanning or MRI to identify and treat these lesions early.
Solitary skeletal metastases from primary colorectal tumours are rare.
Skeletal metastases from primary colorectal tumours tend to occur in small, non-weight bearing bones including the clavicle.
Isotope bone scans should be used with caution in the detection of skeletal metastases. MRI or bone biopsy may be more useful diagnostic tools.
Written consent was obtained from the patient for publication of this case report.
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